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Updated HttpClient tutorial to 4.3 APIs (fundamentals, conn mgmt and state mgmt chapters) 

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1513603 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Oleg Kalnichevski 2013-08-13 18:15:16 +00:00
parent 64ca74933b
commit 5e2c01472d
10 changed files with 494 additions and 1019 deletions
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9
httpclient/src/main/java/org/apache/http/client/config/CookieSpecs.java
View File

@ -49,14 +49,9 @@ public final class CookieSpecs {
public static final String NETSCAPE = "netscape";
/**
* The RFC 2109 compliant policy.
* The RFC 2965 compliant policy (standard).
*/
public static final String RFC_2109 = "rfc2109";
/**
* The RFC 2965 compliant policy.
*/
public static final String RFC_2965 = "rfc2965";
public static final String STANDARD = "standard";
/**
* The default 'best match' policy.

5
httpclient/src/main/java/org/apache/http/impl/client/HttpClientBuilder.java
View File

@ -690,11 +690,12 @@ public class HttpClientBuilder {
if (cookieSpecRegistry == null) {
cookieSpecRegistry = RegistryBuilder.<CookieSpecProvider>create()
.register(CookieSpecs.BEST_MATCH, new BestMatchSpecFactory())
.register(CookieSpecs.STANDARD, new RFC2965SpecFactory())
.register(CookieSpecs.BROWSER_COMPATIBILITY, new BrowserCompatSpecFactory())
.register(CookieSpecs.NETSCAPE, new NetscapeDraftSpecFactory())
.register(CookieSpecs.RFC_2109, new RFC2109SpecFactory())
.register(CookieSpecs.RFC_2965, new RFC2965SpecFactory())
.register(CookieSpecs.IGNORE_COOKIES, new IgnoreSpecFactory())
.register("rfc2109", new RFC2109SpecFactory())
.register("rfc2965", new RFC2965SpecFactory())
.build();
}

4
httpclient/src/main/java/org/apache/http/impl/conn/DefaultProxyRoutePlanner.java
View File

@ -51,6 +51,10 @@ public class DefaultProxyRoutePlanner extends DefaultRoutePlanner {
this.proxy = Args.notNull(proxy, "Proxy host");
}
public DefaultProxyRoutePlanner(final HttpHost proxy) {
this(proxy, null);
}
@Override
protected HttpHost determineProxy(
final HttpHost target,

4
httpclient/src/main/java/org/apache/http/impl/conn/SystemDefaultRoutePlanner.java
View File

@ -65,6 +65,10 @@ public class SystemDefaultRoutePlanner extends DefaultRoutePlanner {
this.proxySelector = proxySelector != null ? proxySelector : ProxySelector.getDefault();
}
public SystemDefaultRoutePlanner(final ProxySelector proxySelector) {
this(null, proxySelector);
}
@Override
protected HttpHost determineProxy(
final HttpHost target,

4
httpclient/src/test/java/org/apache/http/client/config/TestRequestConfig.java
View File

@ -75,7 +75,7 @@ public class TestRequestConfig {
.setRelativeRedirectsAllowed(false)
.setCircularRedirectsAllowed(true)
.setMaxRedirects(100)
.setCookieSpec(CookieSpecs.RFC_2965)
.setCookieSpec(CookieSpecs.STANDARD)
.setLocalAddress(InetAddress.getLocalHost())
.setProxy(new HttpHost("someproxy"))
.setTargetPreferredAuthSchemes(Arrays.asList(AuthSchemes.NTLM))
@ -92,7 +92,7 @@ public class TestRequestConfig {
Assert.assertEquals(false, config.isRelativeRedirectsAllowed());
Assert.assertEquals(true, config.isCircularRedirectsAllowed());
Assert.assertEquals(100, config.getMaxRedirects());
Assert.assertEquals(CookieSpecs.RFC_2965, config.getCookieSpec());
Assert.assertEquals(CookieSpecs.STANDARD, config.getCookieSpec());
Assert.assertEquals(InetAddress.getLocalHost(), config.getLocalAddress());
Assert.assertEquals(new HttpHost("someproxy"), config.getProxy());
Assert.assertEquals(Arrays.asList(AuthSchemes.NTLM), config.getTargetPreferredAuthSchemes());

4
httpclient/src/test/java/org/apache/http/client/protocol/TestRequestAddCookies.java
View File

@ -52,7 +52,6 @@ import org.apache.http.impl.cookie.BrowserCompatSpec;
import org.apache.http.impl.cookie.BrowserCompatSpecFactory;
import org.apache.http.impl.cookie.IgnoreSpecFactory;
import org.apache.http.impl.cookie.NetscapeDraftSpecFactory;
import org.apache.http.impl.cookie.RFC2109SpecFactory;
import org.apache.http.impl.cookie.RFC2965SpecFactory;
import org.apache.http.message.BasicHttpRequest;
import org.junit.Assert;
@ -82,10 +81,9 @@ public class TestRequestAddCookies {
this.cookieSpecRegistry = RegistryBuilder.<CookieSpecProvider>create()
.register(CookieSpecs.BEST_MATCH, new BestMatchSpecFactory())
.register(CookieSpecs.STANDARD, new RFC2965SpecFactory())
.register(CookieSpecs.BROWSER_COMPATIBILITY, new BrowserCompatSpecFactory())
.register(CookieSpecs.NETSCAPE, new NetscapeDraftSpecFactory())
.register(CookieSpecs.RFC_2109, new RFC2109SpecFactory())
.register(CookieSpecs.RFC_2965, new RFC2965SpecFactory())
.register(CookieSpecs.IGNORE_COOKIES, new IgnoreSpecFactory())
.build();
}

752
src/docbkx/connmgmt.xml
View File

@ -23,119 +23,6 @@
-->
<chapter id="connmgmt">
<title>Connection management</title>
<para>HttpClient assumes complete control over the process of connection initialization and
termination as well as I/O operations on active connections. However various aspects of
connection operations can be influenced using a number of parameters.</para>
<section>
<title>Connection parameters</title>
<para>These are parameters that can influence connection operations:</para>
<itemizedlist>
<listitem>
<formalpara>
<title><constant>CoreConnectionPNames.SO_TIMEOUT</constant>='http.socket.timeout':</title>
<para>defines the socket timeout (<literal>SO_TIMEOUT</literal>) in
milliseconds, which is the timeout for waiting for data or, put differently,
a maximum period inactivity between two consecutive data packets). A timeout
value of zero is interpreted as an infinite timeout. This parameter expects
a value of type <classname>java.lang.Integer</classname>. If this parameter
is not set, read operations will not time out (infinite timeout).</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>CoreConnectionPNames.TCP_NODELAY</constant>='http.tcp.nodelay':</title>
<para>determines whether Nagle's algorithm is to be used. Nagle's algorithm
tries to conserve bandwidth by minimizing the number of segments that are
sent. When applications wish to decrease network latency and increase
performance, they can disable Nagle's algorithm (that is enable
<literal>TCP_NODELAY</literal>. Data will be sent earlier, at the cost
of an increase in bandwidth consumption. This parameter expects a value of
type <classname>java.lang.Boolean</classname>. If this parameter is not set,
<literal>TCP_NODELAY</literal> will be enabled (no delay).</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>CoreConnectionPNames.SOCKET_BUFFER_SIZE</constant>='http.socket.buffer-size':</title>
<para>determines the size of the internal socket buffer used to buffer data
while receiving / transmitting HTTP messages. This parameter expects a value
of type <classname>java.lang.Integer</classname>. If this parameter is not
set, HttpClient will allocate 8192 byte socket buffers.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>CoreConnectionPNames.SO_LINGER</constant>='http.socket.linger':</title>
<para>sets <literal>SO_LINGER</literal> with the specified linger time in
seconds. The maximum timeout value is platform specific. Value 0 implies
that the option is disabled. Value -1 implies that the JRE default is used.
The setting only affects the socket close operation. If this parameter is
not set, the value -1 (JRE default) will be assumed.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>CoreConnectionPNames.CONNECTION_TIMEOUT</constant>='http.connection.timeout':</title>
<para>determines the timeout in milliseconds until a connection is established.
A timeout value of zero is interpreted as an infinite timeout. This
parameter expects a value of type <classname>java.lang.Integer</classname>.
If this parameter is not set, connect operations will not time out (infinite
timeout).</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>CoreConnectionPNames.STALE_CONNECTION_CHECK</constant>='http.connection.stalecheck':</title>
<para>determines whether stale connection check is to be used. Disabling stale
connection check may result in a noticeable performance improvement (the
check can cause up to 30 millisecond overhead per request) at the risk of
getting an I/O error when executing a request over a connection that has
been closed at the server side. This parameter expects a value of type
<classname>java.lang.Boolean</classname>. For performance critical
operations the check should be disabled. If this parameter is not set, the
stale connection check will be performed before each request execution.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>CoreConnectionPNames.MAX_LINE_LENGTH</constant>='http.connection.max-line-length':</title>
<para>determines the maximum line length limit. If set to a positive value, any
HTTP line exceeding this limit will cause an
<exceptionname>java.io.IOException</exceptionname>. A negative or zero
value will effectively disable the check. This parameter expects a value of
type <classname>java.lang.Integer</classname>. If this parameter is not set,
no limit will be enforced.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>CoreConnectionPNames.MAX_HEADER_COUNT</constant>='http.connection.max-header-count':</title>
<para>determines the maximum HTTP header count allowed. If set to a positive
value, the number of HTTP headers received from the data stream exceeding
this limit will cause an <exceptionname>java.io.IOException</exceptionname>.
A negative or zero value will effectively disable the check. This parameter
expects a value of type <classname>java.lang.Integer</classname>. If this
parameter is not set, no limit will be enforced.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>ConnConnectionPNames.MAX_STATUS_LINE_GARBAGE</constant>='http.connection.max-status-line-garbage':</title>
<para>defines the maximum number of ignorable lines before we expect a HTTP
response's status line. With HTTP/1.1 persistent connections, the problem
arises that broken scripts could return a wrong
<literal>Content-Length</literal> (there are more bytes sent than
specified). Unfortunately, in some cases, this cannot be detected after the
bad response, but only before the next one. So HttpClient must be able to
skip those surplus lines this way. This parameter expects a value of type
java.lang.Integer. 0 disallows all garbage/empty lines before the status
line. Use <constant>java.lang.Integer#MAX_VALUE</constant> for unlimited
number. If this parameter is not set, unlimited number will be
assumed.</para>
</formalpara>
</listitem>
</itemizedlist>
</section>
<section>
<title>Connection persistence</title>
<para>The process of establishing a connection from one host to another is quite complex and
@ -166,27 +53,27 @@
proxies.</para>
<section>
<title>Route computation</title>
<para>The <interfacename>RouteInfo</interfacename> interface represents information about a
definitive route to a target host involving one or more intermediate steps or hops.
<classname>HttpRoute</classname> is a concrete implementation of
<para>The <interfacename>RouteInfo</interfacename> interface represents information
about a definitive route to a target host involving one or more intermediate steps
or hops. <classname>HttpRoute</classname> is a concrete implementation of
the <interfacename>RouteInfo</interfacename>, which cannot be changed (is
immutable). <classname>HttpTracker</classname> is a mutable
<interfacename>RouteInfo</interfacename> implementation used internally by
<interfacename>RouteInfo</interfacename> implementation used internally by
HttpClient to track the remaining hops to the ultimate route target.
<classname>HttpTracker</classname> can be updated after a successful execution
<classname>HttpTracker</classname> can be updated after a successful execution
of the next hop towards the route target. <classname>HttpRouteDirector</classname>
is a helper class that can be used to compute the next step in a route. This class
is used internally by HttpClient.</para>
<para><interfacename>HttpRoutePlanner</interfacename> is an interface representing a
strategy to compute a complete route to a given target based on the execution
context. HttpClient ships with two default
<interfacename>HttpRoutePlanner</interfacename> implementations.
<classname>ProxySelectorRoutePlanner</classname> is based on
<classname>java.net.ProxySelector</classname>. By default, it will pick up the
<interfacename>HttpRoutePlanner</interfacename> implementations.
<classname>SystemDefaultRoutePlanner</classname> is based on
<classname>java.net.ProxySelector</classname>. By default, it will pick up the
proxy settings of the JVM, either from system properties or from the browser running
the application. The <classname>DefaultHttpRoutePlanner</classname> implementation does
not make use of any Java system properties, nor any system or browser proxy settings.
It computes routes based exclusively on the HTTP parameters described below.</para>
the application. The <classname>DefaultProxyRoutePlanner</classname> implementation
does not make use of any Java system properties, nor any system or browser proxy
settings. It always computes routes via the same default proxy.</para>
</section>
<section>
<title>Secure HTTP connections</title>
@ -197,364 +84,85 @@
HTTP transport is layered over the SSL/TLS encrypted connection.</para>
</section>
</section>
<section>
<title>HTTP route parameters</title>
<para>These are the parameters that can influence route computation:</para>
<itemizedlist>
<listitem>
<formalpara>
<title><constant>ConnRoutePNames.DEFAULT_PROXY</constant>='http.route.default-proxy':</title>
<para>defines a proxy host to be used by default route planners that do not make
use of JRE settings. This parameter expects a value of type
<classname>HttpHost</classname>. If this parameter is not set, direct
connections to the target will be attempted.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>ConnRoutePNames.LOCAL_ADDRESS</constant>='http.route.local-address':</title>
<para>defines a local address to be used by all default route planner. On
machines with multiple network interfaces, this parameter can be used to
select the network interface from which the connection originates. This
parameter expects a value of type
<classname>java.net.InetAddress</classname>. If this parameter is not
set, a default local address will be used automatically.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>ConnRoutePNames.FORCED_ROUTE</constant>='http.route.forced-route':</title>
<para>defines an forced route to be used by all default route planner. Instead
of computing a route, the given forced route will be returned, even if it
points to a completely different target host. This parameter expects a value
of type <classname>HttpRoute</classname>.</para>
</formalpara>
</listitem>
</itemizedlist>
</section>
<section>
<title>Socket factories</title>
<para>HTTP connections make use of a <classname>java.net.Socket</classname> object
internally to handle transmission of data across the wire. However they rely on
the <interfacename>SchemeSocketFactory</interfacename> interface to create, initialize and
connect sockets. This enables the users of HttpClient to provide application specific
socket initialization code at runtime. <classname>PlainSocketFactory</classname> is the
default factory for creating and initializing plain (unencrypted) sockets.</para>
<para>The process of creating a socket and that of connecting it to a host are decoupled, so
that the socket could be closed while being blocked in the connect operation.</para>
<programlisting><![CDATA[
PlainSocketFactory sf = PlainSocketFactory.getSocketFactory();
Socket socket = sf.createSocket();
HttpParams params = new BasicHttpParams();
params.setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, 1000L);
InetSocketAddress address = new InetSocketAddress("locahost", 8080);
sf.connectSocket(socket, address, null, params);
]]></programlisting>
<section>
<title>Secure socket layering</title>
<para><interfacename>SchemeLayeredSocketFactory</interfacename> is an extension of
the <interfacename>SchemeSocketFactory</interfacename> interface. Layered socket
factories are capable of creating sockets layered over an existing plain socket.
Socket layering is used primarily for creating secure sockets through proxies.
HttpClient ships with <classname>SSLSocketFactory</classname> that implements
SSL/TLS layering. Please note HttpClient does not use any custom encryption
functionality. It is fully reliant on standard Java Cryptography (JCE) and Secure
Sockets (JSEE) extensions.</para>
</section>
<section>
<title>SSL/TLS customization</title>
<para>HttpClient makes use of SSLSocketFactory to create SSL connections.
<classname>SSLSocketFactory</classname> allows for a high degree of
customization. It can take an instance of
<interfacename>javax.net.ssl.SSLContext</interfacename> as a parameter and use
it to create custom configured SSL connections.</para>
<programlisting><![CDATA[
HttpParams params = new BasicHttpParams();
SSLContext sslcontext = SSLContext.getInstance("TLS");
sslcontext.init(null, null, null);
SSLSocketFactory sf = new SSLSocketFactory(sslcontext);
SSLSocket socket = (SSLSocket) sf.createSocket(params);
socket.setEnabledCipherSuites(new String[] { "SSL_RSA_WITH_RC4_128_MD5" });
params.setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, 1000L);
InetSocketAddress address = new InetSocketAddress("locahost", 443);
sf.connectSocket(socket, address, null, params);
]]></programlisting>
<para>Customization of SSLSocketFactory implies a certain degree of familiarity with the
concepts of the SSL/TLS protocol, a detailed explanation of which is out of scope
for this document. Please refer to the <ulink
url="http://java.sun.com/j2se/1.5.0/docs/guide/security/jsse/JSSERefGuide.html"
>Java Secure Socket Extension</ulink> for a detailed description of
<interfacename>javax.net.ssl.SSLContext</interfacename> and related
tools.</para>
</section>
<section>
<title>Hostname verification</title>
<para>In addition to the trust verification and the client authentication performed on
the SSL/TLS protocol level, HttpClient can optionally verify whether the target
hostname matches the names stored inside the server's X.509 certificate, once the
connection has been established. This verification can provide additional guarantees
of authenticity of the server trust material.
The <interfacename>X509HostnameVerifier</interfacename> interface
represents a strategy for hostname verification. HttpClient ships with three
<interfacename>X509HostnameVerifier</interfacename> implementations.
Important: hostname verification should not be confused with
SSL trust verification.</para>
<itemizedlist>
<listitem>
<formalpara>
<title><classname>StrictHostnameVerifier</classname>:</title>
<para>The strict hostname verifier works the same way as Sun Java 1.4, Sun
Java 5, Sun Java 6. It's also pretty close to IE6. This implementation
appears to be compliant with RFC 2818 for dealing with wildcards. The
hostname must match either the first CN, or any of the subject-alts. A
wildcard can occur in the CN, and in any of the subject-alts.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><classname>BrowserCompatHostnameVerifier</classname>:</title>
<para>This hostname verifier that works the same way as Curl and Firefox. The
hostname must match either the first CN, or any of the subject-alts. A
wildcard can occur in the CN, and in any of the subject-alts. The only
difference between <classname>BrowserCompatHostnameVerifier</classname>
and <classname>StrictHostnameVerifier</classname> is that a wildcard
(such as "*.foo.com") with
<classname>BrowserCompatHostnameVerifier</classname> matches all
subdomains, including "a.b.foo.com".</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><classname>AllowAllHostnameVerifier</classname>:</title>
<para>This hostname verifier essentially turns hostname verification off.
This implementation is a no-op, and never throws
<exceptionname>javax.net.ssl.SSLException</exceptionname>.</para>
</formalpara>
</listitem>
</itemizedlist>
<para>Per default HttpClient uses the <classname>BrowserCompatHostnameVerifier</classname>
implementation. One can specify a different hostname verifier implementation if
desired</para>
<programlisting><![CDATA[
SSLContext sslcontext = SSLContext.getInstance("TLS");
sslcontext.init(null, null, null);
SSLSocketFactory sf = new SSLSocketFactory(
sslcontext,
SSLSocketFactory.STRICT_HOSTNAME_VERIFIER);
]]></programlisting>
</section>
</section>
<section>
<title>Protocol schemes</title>
<para>The <classname>Scheme</classname> class represents a protocol scheme such as "http" or
"https" and contains a number of protocol properties such as the default port and the
socket factory to be used to create the <classname>java.net.Socket</classname> instances
for the given protocol. The <classname>SchemeRegistry</classname> class is used to maintain
a set of <classname>Scheme</classname>s that HttpClient can choose from when trying to
establish a connection by a request URI:</para>
<programlisting><![CDATA[
Scheme http = new Scheme("http", 80, PlainSocketFactory.getSocketFactory());
SSLContext sslcontext = SSLContext.getInstance("TLS");
sslcontext.init(null, null, null);
SSLSocketFactory sf = new SSLSocketFactory(
sslcontext,
SSLSocketFactory.STRICT_HOSTNAME_VERIFIER);
Scheme https = new Scheme("https", 443, sf);
SchemeRegistry sr = new SchemeRegistry();
sr.register(http);
sr.register(https);
]]></programlisting>
</section>
<section>
<title>HttpClient proxy configuration</title>
<para>Even though HttpClient is aware of complex routing scemes and proxy chaining, it
supports only simple direct or one hop proxy connections out of the box.</para>
<para>The simplest way to tell HttpClient to connect to the target host via a proxy is by
setting the default proxy parameter:</para>
<programlisting><![CDATA[
DefaultHttpClient httpclient = new DefaultHttpClient();
HttpHost proxy = new HttpHost("someproxy", 8080);
httpclient.getParams().setParameter(ConnRoutePNames.DEFAULT_PROXY, proxy);
]]></programlisting>
<para>One can also instruct HttpClient to use the standard JRE proxy selector to obtain proxy
information:</para>
<programlisting><![CDATA[
DefaultHttpClient httpclient = new DefaultHttpClient();
ProxySelectorRoutePlanner routePlanner = new ProxySelectorRoutePlanner(
httpclient.getConnectionManager().getSchemeRegistry(),
ProxySelector.getDefault());
httpclient.setRoutePlanner(routePlanner);
]]></programlisting>
<para>Alternatively, one can provide a custom <interfacename>RoutePlanner</interfacename>
implementation in order to have a complete control over the process of HTTP route
computation:</para>
<programlisting><![CDATA[
DefaultHttpClient httpclient = new DefaultHttpClient();
httpclient.setRoutePlanner(new HttpRoutePlanner() {
public HttpRoute determineRoute(
HttpHost target,
HttpRequest request,
HttpContext context) throws HttpException {
return new HttpRoute(target, null, new HttpHost("someproxy", 8080),
"https".equalsIgnoreCase(target.getSchemeName()));
}
});
]]></programlisting>
</section>
<section>
<title>HTTP connection managers</title>
<section>
<title>Connection operators</title>
<para>Operated connections are client side connections whose underlying socket or
state can be manipulated by an external entity, usually referred to as a connection
operator. The <interfacename>OperatedClientConnection</interfacename> interface extends
the <interfacename>HttpClientConnection</interfacename> interface and defines
additional methods to manage connection sockets. The
<interfacename>ClientConnectionOperator</interfacename> interface represents a
strategy for creating <interfacename>OperatedClientConnection</interfacename>
instances and updating the underlying socket of those objects. Implementations will
most likely make use a <interfacename>SchemeSocketFactory</interfacename> to create
<classname>java.net.Socket</classname> instances. The
<interfacename>ClientConnectionOperator</interfacename> interface enables
users of HttpClient to provide a custom strategy for connection operators as well as
the ability to provide an alternative implementation of the
<interfacename>OperatedClientConnection</interfacename> interface.</para>
</section>
<section>
<title>Managed connections and connection managers</title>
<para>HTTP connections are complex, stateful, thread-unsafe objects which need to be
properly managed to function correctly. HTTP connections can only be used by one
execution thread at a time. HttpClient employs a special entity to manage access to
HTTP connections called HTTP connection manager and represented by the
<interfacename>ClientConnectionManager</interfacename> interface. The purpose of
an HTTP connection manager is to serve as a factory for new HTTP connections, manage
persistent connections and synchronize access to persistent connections making sure
that only one thread can have access to a connection at a time.</para>
<para>Internally HTTP connection managers work with instances of
<interfacename>OperatedClientConnection</interfacename>, but they return
instances of <interfacename>ManagedClientConnection</interfacename> to the service
consumers. <interfacename>ManagedClientConnection</interfacename> acts as a wrapper
for a <interfacename>OperatedClientConnection</interfacename> instance that manages
its state and controls all I/O operations on that connection. It also abstracts away
socket operations and provides convenience methods for opening and updating sockets
in order to establish a route.
<interfacename>ManagedClientConnection</interfacename> instances are aware of
their link to the connection manager that spawned them and of the fact that they
must be returned back to the manager when no longer in use.
<interfacename>ManagedClientConnection</interfacename> classes also implement
the <interfacename>ConnectionReleaseTrigger</interfacename> interface that can be
used to trigger the release of the connection back to the manager. Once the
connection release has been triggered the wrapped connection gets detached from the
<interfacename>ManagedClientConnection</interfacename> wrapper and the
<interfacename>OperatedClientConnection</interfacename> instance is returned
back to the manager. Even though the service consumer still holds a reference to the
<interfacename>ManagedClientConnection</interfacename> instance, it is no longer
able to execute any I/O operation or change the state of the
<interfacename>OperatedClientConnection</interfacename> either intentionally or
unintentionally.</para>
<interfacename>HttpClientConnectionManager</interfacename> interface. The purpose of
an HTTP connection manager is to serve as a factory for new HTTP connections,
to manage life cycle of persistent connections and to synchronize access to
persistent connections making sure that only one thread can have access
to a connection at a time. Internally HTTP connection managers work with instances
of <interfacename>ManagedHttpClientConnection</interfacename> acting as a proxy
for a real connection that manages connection state and controls execution
of I/O operations. If a managed connection is released or get explicitly closed
by its consumer the underyling connection gets detached from its proxy and is
returned back to the manager. Even though the service consumer still holds
a reference to the proxy instance, it is no longer able to execute any
I/O operations or change the state of the real connection either intentionally
or unintentionally.</para>
<para>This is an example of acquiring a connection from a connection manager:</para>
<programlisting><![CDATA[
Scheme http = new Scheme("http", 80, PlainSocketFactory.getSocketFactory());
SchemeRegistry sr = new SchemeRegistry();
sr.register(http);
ClientConnectionManager connMrg = new BasicClientConnectionManager(sr);
HttpClientContext context = HttpClientContext.create();
HttpClientConnectionManager connMrg = new BasicHttpClientConnectionManager();
HttpRoute route = new HttpRoute(new HttpHost("localhost", 80));
// Request new connection. This can be a long process
ClientConnectionRequest connRequest = connMrg.requestConnection(
new HttpRoute(new HttpHost("localhost", 80)), null);
ConnectionRequest connRequest = connMrg.requestConnection(route, null);
// Wait for connection up to 10 sec
ManagedClientConnection conn = connRequest.getConnection(10, TimeUnit.SECONDS);
HttpClientConnection conn = connRequest.get(10, TimeUnit.SECONDS);
try {
// If not open
if (!conn.isOpen()) {
// establish connection based on its route info
connMrg.connect(conn, route, 1000, context);
// and mark it as route complete
connMrg.routeComplete(conn, route, context);
}
// Do useful things with the connection.
// Release it when done.
conn.releaseConnection();
} catch (IOException ex) {
// Abort connection upon an I/O error.
conn.abortConnection();
throw ex;
} finally {
connMrg.releaseConnection(conn, null, 1, TimeUnit.MINUTES);
}
]]></programlisting>
<para>The connection request can be terminated prematurely by calling
<methodname>ClientConnectionRequest#abortRequest()</methodname> if necessary.
This will unblock the thread blocked in the
<methodname>ClientConnectionRequest#getConnection()</methodname> method.</para>
<para><classname>BasicManagedEntity</classname> wrapper class can be used to ensure
automatic release of the underlying connection once the response content has been
fully consumed. HttpClient uses this mechanism internally to achieve transparent
connection release for all responses obtained from
<methodname>HttpClient#execute()</methodname> methods:</para>
<programlisting><![CDATA[
ClientConnectionRequest connRequest = connMrg.requestConnection(
new HttpRoute(new HttpHost("localhost", 80)), null);
ManagedClientConnection conn = connRequest.getConnection(10, TimeUnit.SECONDS);
try {
BasicHttpRequest request = new BasicHttpRequest("GET", "/");
conn.sendRequestHeader(request);
HttpResponse response = conn.receiveResponseHeader();
conn.receiveResponseEntity(response);
HttpEntity entity = response.getEntity();
if (entity != null) {
BasicManagedEntity managedEntity = new BasicManagedEntity(entity, conn, true);
// Replace entity
response.setEntity(managedEntity);
}
// Do something useful with the response
// The connection will be released automatically
// as soon as the response content has been consumed
} catch (IOException ex) {
// Abort connection upon an I/O error.
conn.abortConnection();
throw ex;
}
]]></programlisting>
<methodname>ConnectionRequest#cancel()</methodname> if necessary. This will unblock
the thread blocked in the <methodname>ConnectionRequest#get()</methodname>
method.</para>
</section>
<section>
<title>Simple connection manager</title>
<para><classname>BasicClientConnectionManager</classname> is a simple connection manager
that maintains only one connection at a time. Even though this class is thread-safe
it ought to be used by one execution thread only.
<classname>BasicClientConnectionManager</classname> will make an effort to reuse
<para><classname>BasicHttpClientConnectionManager</classname> is a simple connection
manager that maintains only one connection at a time. Even though this class
is thread-safe it ought to be used by one execution thread only.
<classname>BasicHttpClientConnectionManager</classname> will make an effort to reuse
the connection for subsequent requests with the same route. It will, however, close
the existing connection and re-open it for the given route, if the route of the
persistent connection does not match that of the connection request.
If the connection has been already been allocated, then <exceptionname>
java.lang.IllegalStateException</exceptionname> is thrown.</para>
<para><classname>BasicClientConnectionManager</classname> is used by HttpClient per
default.</para>
<para>This connection manager implementation should be used inside an EJB
container.</para>
</section>
<section>
<title>Pooling connection manager</title>
<para><classname>PoolingClientConnectionManager</classname> is a more complex
<para><classname>PoolingHttpClientConnectionManager</classname> is a more complex
implementation that manages a pool of client connections and is able to service
connection requests from multiple execution threads. Connections are pooled on a per
route basis. A request for a route for which the manager already has a persistent
connection available in the pool will be serviced by leasing a connection from
the pool rather than creating a brand new connection.</para>
<para><classname>PoolingClientConnectionManager</classname> maintains a maximum limit of
connections on a per route basis and in total. Per default this implementation will
create no more than 2 concurrent connections per given route and no more 20
connections in total. For many real-world applications these limits may prove too
constraining, especially if they use HTTP as a transport protocol for their
services. Connection limits can be adjusted using the appropriate HTTP parameters.</para>
<para><classname>PoolingHttpClientConnectionManager</classname> maintains a maximum
limit of connections on a per route basis and in total. Per default this
implementation will create no more than 2 concurrent connections per given route
and no more 20 connections in total. For many real-world applications these limits
may prove too constraining, especially if they use HTTP as a transport protocol for
their services.</para>
<para>This example shows how the connection pool parameters can be adjusted:</para>
<programlisting><![CDATA[
SchemeRegistry schemeRegistry = new SchemeRegistry();
schemeRegistry.register(
new Scheme("http", 80, PlainSocketFactory.getSocketFactory()));
schemeRegistry.register(
new Scheme("https", 443, SSLSocketFactory.getSocketFactory()));
PoolingClientConnectionManager cm = new PoolingClientConnectionManager(schemeRegistry);
PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager();
// Increase max total connection to 200
cm.setMaxTotal(200);
// Increase default max connection per route to 20
@ -562,8 +170,10 @@ cm.setDefaultMaxPerRoute(20);
// Increase max connections for localhost:80 to 50
HttpHost localhost = new HttpHost("locahost", 80);
cm.setMaxPerRoute(new HttpRoute(localhost), 50);
HttpClient httpClient = new DefaultHttpClient(cm);
CloseableHttpClient httpClient = HttpClients.custom()
.setConnectionManager(cm)
.build();
]]></programlisting>
</section>
<section>
@ -573,13 +183,8 @@ HttpClient httpClient = new DefaultHttpClient(cm);
alive by the manager get closed and system resources allocated by those connections
are released.</para>
<programlisting><![CDATA[
DefaultHttpClient httpclient = new DefaultHttpClient();
HttpGet httpget = new HttpGet("http://www.google.com/");
HttpResponse response = httpclient.execute(httpget);
HttpEntity entity = response.getEntity();
System.out.println(response.getStatusLine());
EntityUtils.consume(entity);
httpclient.getConnectionManager().shutdown();
CloseableHttpClient httpClient = <...>
httpClient.close();
]]></programlisting>
</section>
</section>
@ -597,12 +202,10 @@ httpclient.getConnectionManager().shutdown();
period <exceptionname>ConnectionPoolTimeoutException</exceptionname> will be thrown.
</para>
<programlisting><![CDATA[
SchemeRegistry schemeRegistry = new SchemeRegistry();
schemeRegistry.register(
new Scheme("http", 80, PlainSocketFactory.getSocketFactory()));
ClientConnectionManager cm = new PoolingClientConnectionManager(schemeRegistry);
HttpClient httpClient = new DefaultHttpClient(cm);
PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager();
CloseableHttpClient httpClient = HttpClients.custom()
.setConnectionManager(cm)
.build();
// URIs to perform GETs on
String[] urisToGet = {
@ -636,32 +239,34 @@ for (int j = 0; j < threads.length; j++) {
</interfacename>.</para>
<programlisting><![CDATA[
static class GetThread extends Thread {
private final HttpClient httpClient;
private final CloseableHttpClient httpClient;
private final HttpContext context;
private final HttpGet httpget;
public GetThread(HttpClient httpClient, HttpGet httpget) {
public GetThread(CloseableHttpClient httpClient, HttpGet httpget) {
this.httpClient = httpClient;
this.context = new BasicHttpContext();
this.context = HttpClientContext.create();
this.httpget = httpget;
}
@Override
public void run() {
try {
HttpResponse response = this.httpClient.execute(this.httpget, this.context);
HttpEntity entity = response.getEntity();
if (entity != null) {
// do something useful with the entity
CloseableHttpResponse response = httpClient.execute(
httpget, context);
try {
HttpEntity entity = response.getEntity();
} finally {
response.close();
}
// ensure the connection gets released to the manager
EntityUtils.consume(entity);
} catch (Exception ex) {
this.httpget.abort();
} catch (ClientProtocolException ex) {
// Handle protocol errors
} catch (IOException ex) {
// Handle I/O errors
}
}
}
]]></programlisting>
</section>
@ -687,10 +292,10 @@ static class GetThread extends Thread {
<programlisting><![CDATA[
public static class IdleConnectionMonitorThread extends Thread {
private final ClientConnectionManager connMgr;
private final HttpClientConnectionManager connMgr;
private volatile boolean shutdown;
public IdleConnectionMonitorThread(ClientConnectionManager connMgr) {
public IdleConnectionMonitorThread(HttpClientConnectionManager connMgr) {
super();
this.connMgr = connMgr;
}
@ -736,8 +341,7 @@ public static class IdleConnectionMonitorThread extends Thread {
client. In case the default strategy turns out to be too optimistic, one may want to
provide a custom keep-alive strategy.</para>
<programlisting><![CDATA[
DefaultHttpClient httpclient = new DefaultHttpClient();
httpclient.setKeepAliveStrategy(new ConnectionKeepAliveStrategy() {
ConnectionKeepAliveStrategy myStrategy = new ConnectionKeepAliveStrategy() {
public long getKeepAliveDuration(HttpResponse response, HttpContext context) {
// Honor 'keep-alive' header
@ -745,7 +349,7 @@ httpclient.setKeepAliveStrategy(new ConnectionKeepAliveStrategy() {
response.headerIterator(HTTP.CONN_KEEP_ALIVE));
while (it.hasNext()) {
HeaderElement he = it.nextElement();
String param = he.getName();
String param = he.getName();
String value = he.getValue();
if (value != null && param.equalsIgnoreCase("timeout")) {
try {
@ -755,7 +359,7 @@ httpclient.setKeepAliveStrategy(new ConnectionKeepAliveStrategy() {
}
}
HttpHost target = (HttpHost) context.getAttribute(
ExecutionContext.HTTP_TARGET_HOST);
HttpClientContext.HTTP_TARGET_HOST);
if ("www.naughty-server.com".equalsIgnoreCase(target.getHostName())) {
// Keep alive for 5 seconds only
return 5 * 1000;
@ -764,8 +368,186 @@ httpclient.setKeepAliveStrategy(new ConnectionKeepAliveStrategy() {
return 30 * 1000;
}
}
});
};
CloseableHttpClient client = HttpClients.custom()
.setKeepAliveStrategy(myStrategy)
.build();
]]></programlisting>
</section>
<section>
<title>Connection socket factories</title>
<para>HTTP connections make use of a <classname>java.net.Socket</classname> object
internally to handle transmission of data across the wire. However they rely on
the <interfacename>ConnectionSocketFactory</interfacename> interface to create,
initialize and connect sockets. This enables the users of HttpClient to provide
application specific socket initialization code at runtime. <classname>
PlainConnectionSocketFactory</classname> is the default factory for creating and
initializing plain (unencrypted) sockets.</para>
<para>The process of creating a socket and that of connecting it to a host are decoupled, so
that the socket could be closed while being blocked in the connect operation.</para>
<programlisting><![CDATA[
HttpClientContext clientContext = HttpClientContext.create();
PlainConnectionSocketFactory sf = PlainConnectionSocketFactory.getSocketFactory();
Socket socket = sf.createSocket(clientContext);
int timeout = 1000; //ms
HttpHost target = new HttpHost("localhost");
InetSocketAddress remoteAddress = new InetSocketAddress(
InetAddress.getByAddress(new byte[] {127,0,0,1}), 80);
sf.connectSocket(timeout, socket, target, remoteAddress, null, clientContext);
]]></programlisting>
<section>
<title>Secure socket layering</title>
<para><interfacename>LayeredConnectionSocketFactory</interfacename> is an extension of
the <interfacename>ConnectionSocketFactory</interfacename> interface. Layered socket
factories are capable of creating sockets layered over an existing plain socket.
Socket layering is used primarily for creating secure sockets through proxies.
HttpClient ships with <classname>SSLSocketFactory</classname> that implements
SSL/TLS layering. Please note HttpClient does not use any custom encryption
functionality. It is fully reliant on standard Java Cryptography (JCE) and Secure
Sockets (JSEE) extensions.</para>
</section>
<section>
<title>Integration with connection manager</title>
<para>Custom connection socket factories can be associated with a particular
protocol scheme as as HTTP or HTTPS and then used to create a custom connection
manager.</para>
<programlisting><![CDATA[
ConnectionSocketFactory plainsf = <...>
LayeredConnectionSocketFactory sslsf = <...>
Registry<ConnectionSocketFactory> reg = RegistryBuilder.<ConnectionSocketFactory>create()
.register("http", plainsf)
.register("https", sslsf)
.build();
HttpClientConnectionManager cm = new PoolingHttpClientConnectionManager(reg);
HttpClients.custom()
.setConnectionManager(cm)
.build();
]]></programlisting>
</section>
<section>
<title>SSL/TLS customization</title>
<para>HttpClient makes use of SSLSocketFactory to create SSL connections.
<classname>SSLSocketFactory</classname> allows for a high degree of
customization. It can take an instance of
<interfacename>javax.net.ssl.SSLContext</interfacename> as a parameter and use
it to create custom configured SSL connections.</para>
<programlisting><![CDATA[
HttpClientContext clientContext = HttpClientContext.create();
KeyStore myTrustStore = <...>
SSLContext sslContext = SSLContexts.custom()
.useTLS()
.loadTrustMaterial(myTrustStore)
.build();
SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(sslContext);
]]></programlisting>
<para>Customization of SSLSocketFactory implies a certain degree of familiarity with the
concepts of the SSL/TLS protocol, a detailed explanation of which is out of scope
for this document. Please refer to the <ulink
url="http://java.sun.com/j2se/1.5.0/docs/guide/security/jsse/JSSERefGuide.html"
>Java Secure Socket Extension</ulink> for a detailed description of
<interfacename>javax.net.ssl.SSLContext</interfacename> and related
tools.</para>
</section>
<section>
<title>Hostname verification</title>
<para>In addition to the trust verification and the client authentication performed on
the SSL/TLS protocol level, HttpClient can optionally verify whether the target
hostname matches the names stored inside the server's X.509 certificate, once the
connection has been established. This verification can provide additional guarantees
of authenticity of the server trust material.
The <interfacename>X509HostnameVerifier</interfacename> interface
represents a strategy for hostname verification. HttpClient ships with three
<interfacename>X509HostnameVerifier</interfacename> implementations.
Important: hostname verification should not be confused with
SSL trust verification.</para>
<itemizedlist>
<listitem>
<formalpara>
<title><classname>StrictHostnameVerifier</classname>:</title>
<para>The strict hostname verifier works the same way as Sun Java 1.4, Sun
Java 5, Sun Java 6. It's also pretty close to IE6. This implementation
appears to be compliant with RFC 2818 for dealing with wildcards. The
hostname must match either the first CN, or any of the subject-alts. A
wildcard can occur in the CN, and in any of the subject-alts.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><classname>BrowserCompatHostnameVerifier</classname>:</title>
<para>This hostname verifier that works the same way as Curl and Firefox. The
hostname must match either the first CN, or any of the subject-alts. A
wildcard can occur in the CN, and in any of the subject-alts. The only
difference between <classname>BrowserCompatHostnameVerifier</classname>
and <classname>StrictHostnameVerifier</classname> is that a wildcard
(such as "*.foo.com") with
<classname>BrowserCompatHostnameVerifier</classname> matches all
subdomains, including "a.b.foo.com".</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><classname>AllowAllHostnameVerifier</classname>:</title>
<para>This hostname verifier essentially turns hostname verification off.
This implementation is a no-op, and never throws
<exceptionname>javax.net.ssl.SSLException</exceptionname>.</para>
</formalpara>
</listitem>
</itemizedlist>
<para>Per default HttpClient uses the <classname>BrowserCompatHostnameVerifier</classname>
implementation. One can specify a different hostname verifier implementation if
desired</para>
<programlisting><![CDATA[
SSLContext sslContext = SSLContexts.createSystemDefault();
SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(
sslContext,
SSLConnectionSocketFactory.STRICT_HOSTNAME_VERIFIER);
]]></programlisting>
</section>
</section>
<section>
<title>HttpClient proxy configuration</title>
<para>Even though HttpClient is aware of complex routing scemes and proxy chaining, it
supports only simple direct or one hop proxy connections out of the box.</para>
<para>The simplest way to tell HttpClient to connect to the target host via a proxy is by
setting the default proxy parameter:</para>
<programlisting><![CDATA[
HttpHost proxy = new HttpHost("someproxy", 8080);
DefaultProxyRoutePlanner routePlanner = new DefaultProxyRoutePlanner(proxy);
CloseableHttpClient httpclient = HttpClients.custom()
.setRoutePlanner(routePlanner)
.build();
]]></programlisting>
<para>One can also instruct HttpClient to use the standard JRE proxy selector to obtain proxy
information:</para>
<programlisting><![CDATA[
SystemDefaultRoutePlanner routePlanner = new SystemDefaultRoutePlanner(
ProxySelector.getDefault());
CloseableHttpClient httpclient = HttpClients.custom()
.setRoutePlanner(routePlanner)
.build();
]]></programlisting>
<para>Alternatively, one can provide a custom <interfacename>RoutePlanner</interfacename>
implementation in order to have a complete control over the process of HTTP route
computation:</para>
<programlisting><![CDATA[
HttpRoutePlanner routePlanner = new HttpRoutePlanner() {
public HttpRoute determineRoute(
HttpHost target,
HttpRequest request,
HttpContext context) throws HttpException {
return new HttpRoute(target, null, new HttpHost("someproxy", 8080),
"https".equalsIgnoreCase(target.getSchemeName()));
}
};
CloseableHttpClient httpclient = HttpClients.custom()
.setRoutePlanner(routePlanner)
.build();
}
}
]]></programlisting>
</section>
</chapter>

511
src/docbkx/fundamentals.xml
View File

@ -34,17 +34,13 @@
interface that defines the contract described above. </para>
<para>Here is an example of request execution process in its simplest form:</para>
<programlisting><![CDATA[
HttpClient httpclient = new DefaultHttpClient();
CloseableHttpClient httpclient = HttpClients.createDefault();
HttpGet httpget = new HttpGet("http://localhost/");
HttpResponse response = httpclient.execute(httpget);
HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream instream = entity.getContent();
try {
// do something useful
} finally {
instream.close();
}
CloseableHttpResponse response = httpclient.execute(httpget);
try {
} finally {
response.close();
}
]]></programlisting>
<section>
@ -69,13 +65,15 @@ HttpGet httpget = new HttpGet(
<para>HttpClient provides <classname>URIBuilder</classname> utility class to simplify
creation and modification of request URIs.</para>
<programlisting><![CDATA[
URIBuilder builder = new URIBuilder();
builder.setScheme("http").setHost("www.google.com").setPath("/search")
.setParameter("q", "httpclient")
.setParameter("btnG", "Google Search")
.setParameter("aq", "f")
.setParameter("oq", "");
URI uri = builder.build();
URI uri = new URIBuilder()
.setScheme("http")
.setHost("www.google.com")
.setPath("/search")
.setParameter("q", "httpclient")
.setParameter("btnG", "Google Search")
.setParameter("aq", "f")
.setParameter("oq", "")
.build();
HttpGet httpget = new HttpGet(uri);
System.out.println(httpget.getURI());
]]></programlisting>
@ -282,21 +280,30 @@ important message
</section>
<section>
<title>Ensuring release of low level resources</title>
<para> In order to ensure proper release of system resources one must close the content
stream associated with the entity.</para>
<para> In order to ensure proper release of system resources one must close either
the content stream associated with the entity or the response itself</para>
<programlisting><![CDATA[
HttpResponse response;
HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream instream = entity.getContent();
try {
// do something useful
} finally {
instream.close();
CloseableHttpClient httpclient = <...>
CloseableHttpResponse response = httpclient.execute(httpget);
try {
HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream instream = entity.getContent();
try {
// do something useful
} finally {
instream.close();
}
}
} finally {
response.close();
}
]]></programlisting>
<para>Please note that the <methodname>HttpEntity#writeTo(OutputStream)</methodname>
<para>The difference between closing the content stream and closing the response
is that the former will attempt to keep the underlying connection alive
by consuming the entity content while the latter immediately shuts down
and discards the connection.</para>
<para>Please note that the <methodname>HttpEntity#writeTo(OutputStream)</methodname>
method is also required to ensure proper release of system resources once the
entity has been fully written out. If this method obtains an instance of
<classname>java.io.InputStream</classname> by calling
@ -309,19 +316,20 @@ if (entity != null) {
<para>There can be situations, however, when only a small portion of the entire response
content needs to be retrieved and the performance penalty for consuming the
remaining content and making the connection reusable is too high, in which case
one can simply
terminate the request by calling <methodname>HttpUriRequest#abort()</methodname>
method.</para>
one can terminate the content stream by closing the response.</para>
<programlisting><![CDATA[
HttpGet httpget = new HttpGet("http://localhost/");
HttpResponse response = httpclient.execute(httpget);
HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream instream = entity.getContent();
int byteOne = instream.read();
int byteTwo = instream.read();
// Do not need the rest
httpget.abort();
CloseableHttpClient httpclient = <...>
CloseableHttpResponse response = httpclient.execute(httpget);
try {
HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream instream = entity.getContent();
int byteOne = instream.read();
int byteTwo = instream.read();
// Do not need the rest
}
} finally {
response.close();
}
]]></programlisting>
<para>The connection will not be reused, but all level resources held by it will be
@ -340,16 +348,20 @@ if (entity != null) {
strongly discouraged unless the response entities originate from a trusted HTTP
server and are known to be of limited length.</para>
<programlisting><![CDATA[
HttpGet httpget = new HttpGet("http://localhost/");
HttpResponse response = httpclient.execute(httpget);
HttpEntity entity = response.getEntity();
if (entity != null) {
long len = entity.getContentLength();
if (len != -1 && len < 2048) {
System.out.println(EntityUtils.toString(entity));
} else {
// Stream content out
CloseableHttpClient httpclient = <...>
CloseableHttpResponse response = httpclient.execute(httpget);
try {
HttpEntity entity = response.getEntity();
if (entity != null) {
long len = entity.getContentLength();
if (len != -1 && len < 2048) {
System.out.println(EntityUtils.toString(entity));
} else {
// Stream content out
}
}
} finally {
response.close();
}
]]></programlisting>
<para>In some situations it may be necessary to be able to read entity content more than
@ -359,8 +371,7 @@ if (entity != null) {
the original entity to be read into a in-memory buffer. In all other ways the entity
wrapper will be have the original one.</para>
<programlisting><![CDATA[
HttpGet httpget = new HttpGet("http://localhost/");
HttpResponse response = httpclient.execute(httpget);
CloseableHttpResponse response = <...>
HttpEntity entity = response.getEntity();
if (entity != null) {
entity = new BufferedHttpEntity(entity);
@ -401,7 +412,7 @@ httppost.setEntity(entity);
List<NameValuePair> formparams = new ArrayList<NameValuePair>();
formparams.add(new BasicNameValuePair("param1", "value1"));
formparams.add(new BasicNameValuePair("param2", "value2"));
UrlEncodedFormEntity entity = new UrlEncodedFormEntity(formparams, "UTF-8");
UrlEncodedFormEntity entity = new UrlEncodedFormEntity(formparams, Consts.UTF_8);
HttpPost httppost = new HttpPost("http://localhost/handler.do");
httppost.setEntity(entity);
]]></programlisting>
@ -422,8 +433,8 @@ param1=value1&param2=value2
when using HTTP protocol versions that do not support chunk coding, such as
HTTP/1.0.</para>
<programlisting><![CDATA[
StringEntity entity = new StringEntity("important message",
"text/plain; charset=\"UTF-8\"");
StringEntity entity = new StringEntity("important message",
ContentType.create("plain/text", Consts.UTF_8));
entity.setChunked(true);
HttpPost httppost = new HttpPost("http://localhost/acrtion.do");
httppost.setEntity(entity);
@ -441,22 +452,32 @@ httppost.setEntity(entity);
take care of ensuring release of the connection back to the connection manager
regardless whether the request execution succeeds or causes an exception.</para>
<programlisting><![CDATA[
HttpClient httpclient = new DefaultHttpClient();
HttpGet httpget = new HttpGet("http://localhost/");
HttpClient httpclient = <...>
HttpRequest request = <...>
ResponseHandler<byte[]> handler = new ResponseHandler<byte[]>() {
public byte[] handleResponse(
HttpResponse response) throws ClientProtocolException, IOException {
ResponseHandler<MyJsonObject> rh = new ResponseHandler<MyJsonObject>() {
@Override
public JsonObject handleResponse(
final HttpResponse response) throws IOException {
StatusLine statusLine = response.getStatusLine();
HttpEntity entity = response.getEntity();
if (entity != null) {
return EntityUtils.toByteArray(entity);
} else {
return null;
if (statusLine.getStatusCode() >= 300) {
throw new HttpResponseException(
statusLine.getStatusCode(),
statusLine.getReasonPhrase());
}
if (entity == null) {
throw new ClientProtocolException("Response contains no content");
}
Gson gson = new GsonBuilder().create();
ContentType contentType = ContentType.getOrDefault(entity);
Charset charset = contentType.getCharset();
Reader reader = new InputStreamReader(entity.getContent(), charset);
return gson.fromJson(reader, MyJsonObject.class);
}
};
byte[] response = httpclient.execute(httpget, handler);
MyJsonObject myjson = client.execute(request, rh);
]]></programlisting>
</section>
</section>
@ -476,87 +497,51 @@ byte[] response = httpclient.execute(httpget, handler);
<para><interfacename>HttpContext</interfacename> can contain arbitrary objects and
therefore may be unsafe to share between multiple threads. It is recommended that
each thread of execution maintains its own context.</para>
<para>In the course of HTTP request execution HttpClient adds the following attributes to
the execution context:</para>
<itemizedlist>
<listitem>
<formalpara>
<title><constant>ExecutionContext.HTTP_CONNECTION</constant>='http.connection':</title>
<para><interfacename>HttpConnection</interfacename> instance representing the
actual connection to the target server.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>ExecutionContext.HTTP_TARGET_HOST</constant>='http.target_host':</title>
<para><classname>HttpHost</classname> instance representing the connection
target.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>ExecutionContext.HTTP_PROXY_HOST</constant>='http.proxy_host':</title>
<para><classname>HttpHost</classname> instance representing the connection
proxy, if used</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>ExecutionContext.HTTP_REQUEST</constant>='http.request':</title>
<para><interfacename>HttpRequest</interfacename> instance representing the
actual HTTP request.
The final HttpRequest object in the execution context always represents
the state of the message _exactly_ as it was sent to the target server.
Per default HTTP/1.0 and HTTP/1.1 use relative request URIs.
However if the request is sent via a proxy in a non-tunneling mode then
the URI will be absolute.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>ExecutionContext.HTTP_RESPONSE</constant>='http.response':</title>
<para><interfacename>HttpResponse</interfacename> instance representing the
actual HTTP response.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>ExecutionContext.HTTP_REQ_SENT</constant>='http.request_sent':</title>
<para><classname>java.lang.Boolean</classname> object representing the flag
indicating whether the actual request has been fully transmitted to the
connection target.</para>
</formalpara>
</listitem>
</itemizedlist>
<para>For instance, in order to determine the final redirect target, one can examine the
value of the <literal>http.target_host</literal> attribute after the request
execution:</para>
<para>One can use <classname>HttpClientContext</classname> adaptor class to simplify
interractions with the context state.</para>
<programlisting><![CDATA[
DefaultHttpClient httpclient = new DefaultHttpClient();
HttpContext localContext = new BasicHttpContext();
HttpGet httpget = new HttpGet("http://www.google.com/");
HttpResponse response = httpclient.execute(httpget, localContext);
HttpHost target = (HttpHost) localContext.getAttribute(
ExecutionContext.HTTP_TARGET_HOST);
System.out.println("Final target: " + target);
HttpEntity entity = response.getEntity();
EntityUtils.consume(entity);
}
HttpContext context = <...>
HttpClientContext clientContext = HttpClientContext.adapt(context);
HttpHost target = clientContext.getTargetHost();
HttpRequest request = clientContext.getRequest();
HttpResponse response = clientContext.getResponse();
]]></programlisting>
<para>stdout &gt;</para>
<para>Multiple request sequences that represent a logically related session should be
executed with the same <interfacename>HttpContext</interfacename> instance to ensure
automatic propagation of conversation context and state information between
requests.</para>
<para>In the following example the request configuration set by the initial request will be
kept in the execution context and get propagatd to the consecutive requests sharing
the same context.</para>
<programlisting><![CDATA[
Final target: http://www.google.ch
CloseableHttpClient httpclient = <...>
RequestConfig requestConfig = RequestConfig.custom()
.setSocketTimeout(1000)
.setConnectTimeout(1000)
.build();
HttpGet httpget1 = new HttpGet("http://localhost/1");
httpget1.setConfig(requestConfig);
CloseableHttpResponse response1 = httpclient.execute(httpget1, context);
try {
HttpEntity entity1 = response1.getEntity();
} finally {
response1.close();
}
HttpGet httpget2 = new HttpGet("http://localhost/2");
CloseableHttpResponse response2 = httpclient.execute(httpget2, context);
try {
HttpEntity entity2 = response2.getEntity();
} finally {
response2.close();
}
]]></programlisting>
</section>
<section>
<title>Exception handling</title>
<para>HttpClient can throw two types of exceptions:
<exceptionname>java.io.IOException</exceptionname> in case of an I/O failure such as
<exceptionname>java.io.IOException</exceptionname> in case of an I/O failure such as
socket timeout or an socket reset and <exceptionname>HttpException</exceptionname> that
signals an HTTP failure such as a violation of the HTTP protocol. Usually I/O errors are
considered non-fatal and recoverable, whereas HTTP protocol errors are considered fatal
@ -628,12 +613,10 @@ Final target: http://www.google.ch
implementation of the <interfacename>HttpRequestRetryHandler</interfacename>
interface.</para>
<programlisting><![CDATA[
DefaultHttpClient httpclient = new DefaultHttpClient();
HttpRequestRetryHandler myRetryHandler = new HttpRequestRetryHandler() {
public boolean retryRequest(
IOException exception,
IOException exception,
int executionCount,
HttpContext context) {
if (executionCount >= 5) {
@ -648,7 +631,7 @@ HttpRequestRetryHandler myRetryHandler = new HttpRequestRetryHandler() {
// Unknown host
return false;
}
if (exception instanceof ConnectException) {
if (exception instanceof ConnectTimeoutException) {
// Connection refused
return false;
}
@ -656,19 +639,20 @@ HttpRequestRetryHandler myRetryHandler = new HttpRequestRetryHandler() {
// SSL handshake exception
return false;
}
HttpRequest request = (HttpRequest) context.getAttribute(
ExecutionContext.HTTP_REQUEST);
boolean idempotent = !(request instanceof HttpEntityEnclosingRequest);
HttpClientContext clientContext = HttpClientContext.adapt(context);
HttpRequest request = clientContext.getRequest();
boolean idempotent = !(request instanceof HttpEntityEnclosingRequest);
if (idempotent) {
// Retry if the request is considered idempotent
// Retry if the request is considered idempotent
return true;
}
return false;
}
};
httpclient.setHttpRequestRetryHandler(myRetryHandler);
CloseableHttpClient httpclient = HttpClients.custom()
.setRetryHandler(myRetryHandler)
.build();
]]></programlisting>
</section>
</section>
@ -708,227 +692,32 @@ httpclient.setHttpRequestRetryHandler(myRetryHandler);
<para>This is an example of how local context can be used to persist a processing state
between consecutive requests:</para>
<programlisting><![CDATA[
DefaultHttpClient httpclient = new DefaultHttpClient();
CloseableHttpClient httpclient = HttpClients.custom()
.addInterceptorLast(new HttpRequestInterceptor() {
HttpContext localContext = new BasicHttpContext();
public void process(
final HttpRequest request,
final HttpContext context) throws HttpException, IOException {
AtomicInteger count = (AtomicInteger) context.getAttribute("count");
request.addHeader("Count", Integer.toString(count.getAndIncrement()));
}
})
.build();
AtomicInteger count = new AtomicInteger(1);
HttpClientContext localContext = HttpClientContext.create();
localContext.setAttribute("count", count);
httpclient.addRequestInterceptor(new HttpRequestInterceptor() {
public void process(
final HttpRequest request,
final HttpContext context) throws HttpException, IOException {
AtomicInteger count = (AtomicInteger) context.getAttribute("count");
request.addHeader("Count", Integer.toString(count.getAndIncrement()));
}
});
HttpGet httpget = new HttpGet("http://localhost/");
for (int i = 0; i < 10; i++) {
HttpResponse response = httpclient.execute(httpget, localContext);
HttpEntity entity = response.getEntity();
EntityUtils.consume(entity);
CloseableHttpResponse response = httpclient.execute(httpget, localContext);
try {
HttpEntity entity = response.getEntity();
} finally {
response.close();
}
}
]]></programlisting>
</section>
<section>
<title>HTTP parameters</title>
<para>The HttpParams interface represents a collection of immutable values that define a runtime
behavior of a component. In many ways <interfacename>HttpParams</interfacename> is
similar to <interfacename>HttpContext</interfacename>. The main distinction between the
two lies in their use at runtime. Both interfaces represent a collection of objects that
are organized as a map of keys to object values, but serve distinct purposes:</para>
<itemizedlist>
<listitem>
<para><interfacename>HttpParams</interfacename> is intended to contain simple
objects: integers, doubles, strings, collections and objects that remain
immutable at runtime.</para>
</listitem>
<listitem>
<para>
<interfacename>HttpParams</interfacename> is expected to be used in the 'write
once - ready many' mode. <interfacename>HttpContext</interfacename> is intended
to contain complex objects that are very likely to mutate in the course of HTTP
message processing. </para>
</listitem>
<listitem>
<para>The purpose of <interfacename>HttpParams</interfacename> is to define a
behavior of other components. Usually each complex component has its own
<interfacename>HttpParams</interfacename> object. The purpose of
<interfacename>HttpContext</interfacename> is to represent an execution
state of an HTTP process. Usually the same execution context is shared among
many collaborating objects.</para>
</listitem>
</itemizedlist>
<section>
<title>Parameter hierarchies</title>
<para>In the course of HTTP request execution <interfacename>HttpParams</interfacename>
of the <interfacename>HttpRequest</interfacename> object are linked together with
<interfacename>HttpParams</interfacename> of the
<interfacename>HttpClient</interfacename> instance used to execute the request.
This enables parameters set at the HTTP request level to take precedence over
<interfacename>HttpParams</interfacename> set at the HTTP client level. The
recommended practice is to set common parameters shared by all HTTP requests at the
HTTP client level and selectively override specific parameters at the HTTP request
level.</para>
<programlisting><![CDATA[
DefaultHttpClient httpclient = new DefaultHttpClient();
httpclient.getParams().setParameter(CoreProtocolPNames.PROTOCOL_VERSION,
HttpVersion.HTTP_1_0); // Default to HTTP 1.0
httpclient.getParams().setParameter(CoreProtocolPNames.HTTP_CONTENT_CHARSET,
"UTF-8");
HttpGet httpget = new HttpGet("http://www.google.com/");
httpget.getParams().setParameter(CoreProtocolPNames.PROTOCOL_VERSION,
HttpVersion.HTTP_1_1); // Use HTTP 1.1 for this request only
httpget.getParams().setParameter(CoreProtocolPNames.USE_EXPECT_CONTINUE,
Boolean.FALSE);
httpclient.addRequestInterceptor(new HttpRequestInterceptor() {
public void process(
final HttpRequest request,
final HttpContext context) throws HttpException, IOException {
System.out.println(request.getParams().getParameter(
CoreProtocolPNames.PROTOCOL_VERSION));
System.out.println(request.getParams().getParameter(
CoreProtocolPNames.HTTP_CONTENT_CHARSET));
System.out.println(request.getParams().getParameter(
CoreProtocolPNames.USE_EXPECT_CONTINUE));
System.out.println(request.getParams().getParameter(
CoreProtocolPNames.STRICT_TRANSFER_ENCODING));
}
});
]]></programlisting>
<para>stdout &gt;</para>
<programlisting><![CDATA[
HTTP/1.1
UTF-8
false
null
]]></programlisting>
</section>
<section>
<title>HTTP parameters beans</title>
<para>The <interfacename>HttpParams</interfacename> interface allows for a great deal of
flexibility in handling configuration of components. Most importantly, new
parameters can be introduced without affecting binary compatibility with older
versions. However, <interfacename>HttpParams</interfacename> also has a certain
disadvantage compared to regular Java beans:
<interfacename>HttpParams</interfacename> cannot be assembled using a DI
framework. To mitigate the limitation, HttpClient includes a number of bean classes
that can used in order to initialize <interfacename>HttpParams</interfacename>
objects using standard Java bean conventions.</para>
<programlisting><![CDATA[
HttpParams params = new BasicHttpParams();
HttpProtocolParamBean paramsBean = new HttpProtocolParamBean(params);
paramsBean.setVersion(HttpVersion.HTTP_1_1);
paramsBean.setContentCharset("UTF-8");
paramsBean.setUseExpectContinue(true);
System.out.println(params.getParameter(
CoreProtocolPNames.PROTOCOL_VERSION));
System.out.println(params.getParameter(
CoreProtocolPNames.HTTP_CONTENT_CHARSET));
System.out.println(params.getParameter(
CoreProtocolPNames.USE_EXPECT_CONTINUE));
System.out.println(params.getParameter(
CoreProtocolPNames.USER_AGENT));
]]></programlisting>
<para>stdout &gt;</para>
<programlisting><![CDATA[
HTTP/1.1
UTF-8
false
null
]]></programlisting>
</section>
</section>
<section>
<title>HTTP request execution parameters</title>
<para>These are parameters that can impact the process of request execution:</para>
<itemizedlist>
<listitem>
<formalpara>
<title><constant>CoreProtocolPNames.PROTOCOL_VERSION</constant>='http.protocol.version':</title>
<para>defines HTTP protocol version used if not set explicitly on the request
object. This parameter expects a value of type
<interfacename>ProtocolVersion</interfacename>. If this parameter is not
set HTTP/1.1 will be used.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>CoreProtocolPNames.HTTP_ELEMENT_CHARSET</constant>='http.protocol.element-charset':</title>
<para>defines the charset to be used for encoding HTTP protocol elements. This
parameter expects a value of type <classname>java.lang.String</classname>.
If this parameter is not set <literal>US-ASCII</literal> will be
used.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>CoreProtocolPNames.HTTP_CONTENT_CHARSET</constant>='http.protocol.content-charset':</title>
<para>defines the charset to be used per default for content body coding. This
parameter expects a value of type <classname>java.lang.String</classname>.
If this parameter is not set <literal>ISO-8859-1</literal> will be
used.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>CoreProtocolPNames.USER_AGENT</constant>='http.useragent':</title>
<para>defines the content of the <literal>User-Agent</literal> header. This
parameter expects a value of type <classname>java.lang.String</classname>.
If this parameter is not set, HttpClient will automatically generate a value
for it.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>CoreProtocolPNames.STRICT_TRANSFER_ENCODING</constant>='http.protocol.strict-transfer-encoding':</title>
<para>defines whether responses with an invalid
<literal>Transfer-Encoding</literal> header should be rejected. This
parameter expects a value of type <classname>java.lang.Boolean</classname>.
If this parameter is not set, invalid <literal>Transfer-Encoding</literal>
values will be ignored.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>CoreProtocolPNames.USE_EXPECT_CONTINUE</constant>='http.protocol.expect-continue':</title>
<para>activates the <literal>Expect: 100-Continue</literal> handshake for the entity
enclosing methods. The purpose of the <literal>Expect:
100-Continue</literal> handshake is to allow the client that is sending
a request message with a request body to determine if the origin server is
willing to accept the request (based on the request headers) before the
client sends the request body. The use of the <literal>Expect:
100-continue</literal> handshake can result in a noticeable performance
improvement for entity enclosing requests (such as <literal>POST</literal>
and <literal>PUT</literal>) that require the target server's authentication.
The <literal>Expect: 100-continue</literal> handshake should be used with
caution, as it may cause problems with HTTP servers and proxies that do not
support HTTP/1.1 protocol. This parameter expects a value of type
<classname>java.lang.Boolean</classname>. If this parameter is not set,
HttpClient will not attempt to use the handshake.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>CoreProtocolPNames.WAIT_FOR_CONTINUE</constant>='http.protocol.wait-for-continue':</title>
<para>defines the maximum period of time in milliseconds the client should spend
waiting for a <literal>100-continue</literal> response. This parameter
expects a value of type <classname>java.lang.Integer</classname>. If this
parameter is not set HttpClient will wait 3 seconds for a confirmation
before resuming the transmission of the request body.</para>
</formalpara>
</listitem>
</itemizedlist>
</section>
</chapter>

6
src/docbkx/preface.xml
View File

@ -70,9 +70,9 @@
<para>
HttpClient is NOT a browser. It is a client side HTTP transport library.
HttpClient's purpose is to transmit and receive HTTP messages. HttpClient will not
attempt to cache content, execute javascript embedded in HTML pages, try to guess
content type, or reformat request / redirect location URIs, or other functionality
unrelated to the HTTP transport.
attempt to process content, execute javascript embedded in HTML pages, try to guess
content type, if not explicitly set, or reformat request / redirect location URIs,
or other functionality unrelated to the HTTP transport.
</para>
</listitem>
</itemizedlist>

214
src/docbkx/statemgmt.xml
View File

@ -133,15 +133,8 @@ stdCookie.setAttribute(ClientCookie.PORT_ATTR, "80,8080");
</listitem>
<listitem>
<formalpara>
<title>RFC 2109:</title>
<para>Older version of the official HTTP state management specification
superseded by RFC 2965.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title>RFC 2965:</title>
<para>The official HTTP state management specification.</para>
<title>Standard:</title>
<para>RFC 2965 HTTP state management specification.</para>
</formalpara>
</listitem>
<listitem>
@ -171,137 +164,61 @@ stdCookie.setAttribute(ClientCookie.PORT_ATTR, "80,8080");
HttpClient pick up an appropriate compliance level at runtime based on the execution
context.</para>
</section>
<section>
<title>HTTP cookie and state management parameters</title>
<para>These are parameters that be used to customize HTTP state management and the behaviour of
individual cookie specifications:</para>
<itemizedlist>
<listitem>
<formalpara>
<title><constant>CookieSpecPNames.DATE_PATTERNS</constant>='http.protocol.cookie-datepatterns':</title>
<para>defines valid date patterns to be used for parsing non-standard
<literal>expires</literal> attribute. Only required for compatibility
with non-compliant servers that still use <literal>expires</literal> defined
in the Netscape draft instead of the standard <literal>max-age</literal>
attribute. This parameter expects a value of type
<interfacename>java.util.Collection</interfacename>. The collection
elements must be of type <classname>java.lang.String</classname> compatible
with the syntax of <classname>java.text.SimpleDateFormat</classname>. If
this parameter is not set the choice of a default value is
<interfacename>CookieSpec</interfacename> implementation specific.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>CookieSpecPNames.SINGLE_COOKIE_HEADER</constant>='http.protocol.single-cookie-header':</title>
<para>defines whether cookies should be forced into a single
<literal>Cookie</literal> request header. Otherwise, each cookie is
formatted as a separate <literal>Cookie</literal> header. This parameter
expects a value of type <classname>java.lang.Boolean</classname>. If this
parameter is not set, the choice of a default value is CookieSpec
implementation specific. Please note this parameter applies to strict cookie
specifications (RFC 2109 and RFC 2965) only. Browser compatibility and
netscape draft policies will always put all cookies into one request
header.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>ClientPNames.COOKIE_POLICY</constant>='http.protocol.cookie-policy':</title>
<para>defines the name of a cookie specification to be used for HTTP state
management. This parameter expects a value of type
<classname>java.lang.String</classname>. If this parameter is not set,
valid date patterns are <interfacename>CookieSpec</interfacename>
implementation specific.</para>
</formalpara>
</listitem>
</itemizedlist>
</section>
<section>
<title>Cookie specification registry</title>
<para>HttpClient maintains a registry of available cookie specifications using
the <classname>CookieSpecRegistry</classname> class. The following specifications are
registered per default:</para>
<itemizedlist>
<listitem>
<formalpara>
<title>compatibility:</title>
<para> Browser compatibility (lenient policy).</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title>netscape:</title>
<para>Netscape draft.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title>rfc2109:</title>
<para>RFC 2109 (outdated strict policy).</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title>rfc2965:</title>
<para>RFC 2965 (standard conformant strict policy).</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title>best-match:</title>
<para>Best match meta-policy.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title>ignoreCookies:</title>
<para>All cookies are ignored.</para>
</formalpara>
</listitem>
</itemizedlist>
</section>
<section>
<title>Choosing cookie policy</title>
<para>Cookie policy can be set at the HTTP client and overridden on the HTTP request level
if required.</para>
<programlisting><![CDATA[
HttpClient httpclient = new DefaultHttpClient();
// force strict cookie policy per default
httpclient.getParams().setParameter(
ClientPNames.COOKIE_POLICY, CookiePolicy.RFC_2965);
HttpGet httpget = new HttpGet("http://www.broken-server.com/");
// Override the default policy for this request
httpget.getParams().setParameter(
ClientPNames.COOKIE_POLICY, CookiePolicy.BROWSER_COMPATIBILITY);
RequestConfig globalConfig = RequestConfig.custom()
.setCookieSpec(CookieSpecs.BEST_MATCH)
.build();
CloseableHttpClient httpclient = HttpClients.custom()
.setDefaultRequestConfig(globalConfig)
.build();
RequestConfig localConfig = RequestConfig.copy(globalConfig)
.setCookieSpec(CookieSpecs.BROWSER_COMPATIBILITY)
.build();
HttpGet httpGet = new HttpGet("/");
httpGet.setConfig(localConfig);
]]></programlisting>
</section>
<section>
<title>Custom cookie policy</title>
<para>In order to implement a custom cookie policy one should create a custom implementation
of the <interfacename>CookieSpec</interfacename> interface, create a
<interfacename>CookieSpecFactory</interfacename> implementation to create and
<interfacename>CookieSpecProvider</interfacename> implementation to create and
initialize instances of the custom specification and register the factory with
HttpClient. Once the custom specification has been registered, it can be activated the
same way as a standard cookie specification.</para>
<programlisting><![CDATA[
CookieSpecFactory csf = new CookieSpecFactory() {
public CookieSpec newInstance(HttpParams params) {
return new BrowserCompatSpec() {
CookieSpecProvider easySpecProvider = new CookieSpecProvider() {
public CookieSpec create(HttpContext context) {
return new BrowserCompatSpec() {
@Override
public void validate(Cookie cookie, CookieOrigin origin)
throws MalformedCookieException {
throws MalformedCookieException {
// Oh, I am easy
}
};
}
};
DefaultHttpClient httpclient = new DefaultHttpClient();
httpclient.getCookieSpecs().register("easy", csf);
httpclient.getParams().setParameter(
ClientPNames.COOKIE_POLICY, "easy");
};
Registry<CookieSpecProvider> cookieSpecReg = RegistryBuilder.<CookieSpecProvider>create()
.register(CookieSpecs.BEST_MATCH, new BestMatchSpecFactory())
.register(CookieSpecs.BROWSER_COMPATIBILITY, new BrowserCompatSpecFactory())
.register("easy", easySpecProvider)
.build();
RequestConfig requestConfig = RequestConfig.custom()
.setCookieSpec("easy")
.build();
CloseableHttpClient httpclient = HttpClients.custom()
.setDefaultCookieSpecRegistry(cookieSpecReg)
.setDefaultRequestConfig(requestConfig)
.build();
]]></programlisting>
</section>
<section>
@ -315,17 +232,18 @@ httpclient.getParams().setParameter(
get garbage collected. Users can provide more complex implementations if
necessary.</para>
<programlisting><![CDATA[
DefaultHttpClient httpclient = new DefaultHttpClient();
// Create a local instance of cookie store
CookieStore cookieStore = new MyCookieStore();
CookieStore cookieStore = new BasicCookieStore();
// Populate cookies if needed
BasicClientCookie cookie = new BasicClientCookie("name", "value");
cookie.setVersion(0);
cookie.setDomain(".mycompany.com");
cookie.setPath("/");
cookieStore.addCookie(cookie);
// Set the store
httpclient.setCookieStore(cookieStore);
// Set the store
CloseableHttpClient httpclient = HttpClients.custom()
.setDefaultCookieStore(cookieStore)
.build();
]]></programlisting>
</section>
<section>
@ -335,7 +253,6 @@ httpclient.setCookieStore(cookieStore);
<itemizedlist>
<listitem>
<formalpara>
<title><constant>ClientContext.COOKIESPEC_REGISTRY</constant>='http.cookiespec-registry':</title>
<para><classname>CookieSpecRegistry</classname> instance representing the actual
cookie specification registry. The value of this attribute set in the local
context takes precedence over the default one.</para>
@ -343,21 +260,18 @@ httpclient.setCookieStore(cookieStore);
</listitem>
<listitem>
<formalpara>
<title><constant>ClientContext.COOKIE_SPEC</constant>='http.cookie-spec':</title>
<para><interfacename>CookieSpec</interfacename> instance representing the actual
cookie specification.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>ClientContext.COOKIE_ORIGIN</constant>='http.cookie-origin':</title>
<para><classname>CookieOrigin</classname> instance representing the actual
details of the origin server.</para>
</formalpara>
</listitem>
<listitem>
<formalpara>
<title><constant>ClientContext.COOKIE_STORE</constant>='http.cookie-store':</title>
<para><interfacename>CookieStore</interfacename> instance representing the actual
cookie store. The value of this attribute set in the local context takes
precedence over the default one.</para>
@ -366,38 +280,26 @@ httpclient.setCookieStore(cookieStore);
</itemizedlist>
<para>The local <interfacename>HttpContext</interfacename> object can be used to customize
the HTTP state management context prior to request execution, or to examine its state after
the request has been executed:</para>
the request has been executed. One can also use separate execution contexts in order
to implement per user (or per thread) state management. A cookie specification registry
and cookie store defined in the local context will take precedence over the default
ones set at the HTTP client level</para>
<programlisting><![CDATA[
HttpClient httpclient = new DefaultHttpClient();
HttpContext localContext = new BasicHttpContext();
HttpGet httpget = new HttpGet("http://localhost:8080/");
HttpResponse response = httpclient.execute(httpget, localContext);
CloseableHttpClient httpclient = <...>
CookieOrigin cookieOrigin = (CookieOrigin) localContext.getAttribute(
ClientContext.COOKIE_ORIGIN);
System.out.println("Cookie origin: " + cookieOrigin);
CookieSpec cookieSpec = (CookieSpec) localContext.getAttribute(
ClientContext.COOKIE_SPEC);
System.out.println("Cookie spec used: " + cookieSpec);
]]></programlisting>
</section>
<section>
<title>Per user / thread state management</title>
<para>One can use an individual local execution context in order to implement per user (or
per thread) state management. A cookie specification registry and cookie store defined in
the local context will take precedence over the default ones set at the HTTP client
level.</para>
<programlisting><![CDATA[
HttpClient httpclient = new DefaultHttpClient();
// Create a local instance of cookie store
CookieStore cookieStore = new BasicCookieStore();
// Create local HTTP context
HttpContext localContext = new BasicHttpContext();
// Bind custom cookie store to the local context
localContext.setAttribute(ClientContext.COOKIE_STORE, cookieStore);
HttpGet httpget = new HttpGet("http://www.google.com/");
// Pass local context as a parameter
HttpResponse response = httpclient.execute(httpget, localContext);
Registry<CookieSpecProvider> cookieSpecReg = <...>
CookieStore cookieStore = <...>
HttpClientContext context = HttpClientContext.create();
context.setCookieSpecRegistry(cookieSpecReg);
context.setCookieStore(cookieStore);
HttpGet httpget = new HttpGet("http://localhost/1");
CloseableHttpResponse response1 = httpclient.execute(httpget, context);
<...>
// Cookie origin details
CookieOrigin cookieOrigin = context.getCookieOrigin();
// Cookie spec used
CookieSpec cookieSpec = context.getCookieSpec();
]]></programlisting>
</section>
</chapter>