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- refactored FactoryFinder so that it Implementation is pluggable. 

- made an OSGi friendly strategy for it using a BundleActivator (needs testing)



git-svn-id: https://svn.apache.org/repos/asf/activemq/trunk@816444 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Hiram R. Chirino 2009-09-18 02:49:21 +00:00
parent 583d8490fa
commit 76381791e8
4 changed files with 340 additions and 70 deletions
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7
activemq-core/pom.xml
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@ -88,6 +88,13 @@
<!-- =============================== -->
<!-- Optional Dependencies -->
<!-- =============================== -->
<dependency>
<groupId>org.osgi</groupId>
<artifactId>org.osgi.core</artifactId>
</dependency>
<dependency>
<groupId>org.apache.activemq</groupId>
<artifactId>activemq-jaas</artifactId>

94
activemq-core/src/main/java/org/apache/activemq/util/FactoryFinder.java
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@ -22,44 +22,50 @@ import java.io.InputStream;
import java.util.Properties;
import java.util.concurrent.ConcurrentHashMap;
/**
*
*/
public class FactoryFinder {
private final String path;
private final ConcurrentHashMap<String, Class> classMap = new ConcurrentHashMap<String, Class>();
/**
* The strategey that the FactoryFinder uses to find load and instanciate Objects
* can be chagned out by calling the
* {@link org.apache.activemq.util.FactoryFinder#setObjectFactory(org.apache.activemq.util.FactoryFinder.ObjectFactory)}
* method with a custom implemenation of ObjectFactory.
*
* The default ObjectFactory is typically changed out when running in a specialized container
* enviorment where service discovery needs to be done via the container system. For example,
* in an OSGi scenario.
*/
public interface ObjectFactory {
/**
* @param path the full service path
* @return
*/
public Object create(String path) throws IllegalAccessException, InstantiationException, IOException, ClassNotFoundException;
public FactoryFinder(String path) {
this.path = path;
}
/**
* Creates a new instance of the given key
*
* @param key is the key to add to the path to find a text file containing
* the factory name
* @return a newly created instance
* The default implementation of Object factory which works well in standalone applications.
*/
public Object newInstance(String key) throws IllegalAccessException, InstantiationException, IOException, ClassNotFoundException {
return newInstance(key, null);
}
protected static class StandaloneObjectFactory implements ObjectFactory {
final ConcurrentHashMap<String, Class> classMap = new ConcurrentHashMap<String, Class>();
public Object newInstance(String key, String propertyPrefix) throws IllegalAccessException, InstantiationException, IOException, ClassNotFoundException {
if (propertyPrefix == null) {
propertyPrefix = "";
}
Class clazz = classMap.get(propertyPrefix + key);
public Object create(final String path) throws InstantiationException, IllegalAccessException, ClassNotFoundException, IOException {
Class clazz = classMap.get(path);
if (clazz == null) {
clazz = newInstance(doFindFactoryProperies(key), propertyPrefix);
classMap.put(propertyPrefix + key, clazz);
clazz = loadClass(loadProperties(path));
classMap.put(path, clazz);
}
return clazz.newInstance();
}
private Class newInstance(Properties properties, String propertyPrefix) throws ClassNotFoundException, IOException {
static public Class loadClass(Properties properties) throws ClassNotFoundException, IOException {
String className = properties.getProperty(propertyPrefix + "class");
String className = properties.getProperty("class");
if (className == null) {
throw new IOException("Expected property is missing: " + propertyPrefix + "class");
throw new IOException("Expected property is missing: class");
}
Class clazz = null;
ClassLoader loader = Thread.currentThread().getContextClassLoader();
@ -77,13 +83,11 @@ public class FactoryFinder {
return clazz;
}
private Properties doFindFactoryProperies(String key) throws IOException {
String uri = path + key;
static public Properties loadProperties(String uri) throws IOException {
// lets try the thread context class loader first
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
if (classLoader == null) {
classLoader = getClass().getClassLoader();
classLoader = StandaloneObjectFactory.class.getClassLoader();
}
InputStream in = classLoader.getResourceAsStream(uri);
if (in == null) {
@ -107,4 +111,40 @@ public class FactoryFinder {
}
}
}
}
// ================================================================
// Class methods and properties
// ================================================================
private static ObjectFactory objectFactory = new StandaloneObjectFactory();
public static ObjectFactory getObjectFactory() {
return objectFactory;
}
public static void setObjectFactory(ObjectFactory objectFactory) {
FactoryFinder.objectFactory = objectFactory;
}
// ================================================================
// Instance methods and properties
// ================================================================
private final String path;
public FactoryFinder(String path) {
this.path = path;
}
/**
* Creates a new instance of the given key
*
* @param key is the key to add to the path to find a text file containing
* the factory name
* @return a newly created instance
*/
public Object newInstance(String key) throws IllegalAccessException, InstantiationException, IOException, ClassNotFoundException {
return objectFactory.create(path+key);
}
}

216
activemq-core/src/main/java/org/apache/activemq/util/osgi/Activator.java Normal file
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@ -0,0 +1,216 @@
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.activemq.util.osgi;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.util.Properties;
import java.util.ArrayList;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.net.URL;
import org.apache.activemq.util.FactoryFinder;
import org.apache.activemq.util.FactoryFinder.ObjectFactory;
import org.apache.commons.logging.LogFactory;
import org.apache.commons.logging.Log;
import org.osgi.framework.Bundle;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.BundleEvent;
import org.osgi.framework.SynchronousBundleListener;
/**
* An OSGi bundle activator for ActiveMQ which adapts the {@link org.apache.activemq.util.FactoryFinder}
* to the OSGi enviorment.
*
*/
public class Activator implements BundleActivator, SynchronousBundleListener, ObjectFactory {
private static final Log LOG = LogFactory.getLog(Activator.class);
private final ConcurrentHashMap<String, Class> serviceCache = new ConcurrentHashMap<String, Class>();
private final ConcurrentMap<Long, BundleWrapper> bundleWrappers = new ConcurrentHashMap<Long, BundleWrapper>();
private BundleContext bundleContext;
// ================================================================
// BundleActivator interface impl
// ================================================================
public synchronized void start(BundleContext bundleContext) throws Exception {
// This is how we replace the default FactoryFinder strategy
// with one that is more compatible in an OSGi env.
FactoryFinder.setObjectFactory(this);
debug("activating");
this.bundleContext = bundleContext;
debug("checking existing bundles");
for (Bundle bundle : bundleContext.getBundles()) {
if (bundle.getState() == Bundle.RESOLVED || bundle.getState() == Bundle.STARTING ||
bundle.getState() == Bundle.ACTIVE || bundle.getState() == Bundle.STOPPING) {
register(bundle);
}
}
debug("activated");
}
public synchronized void stop(BundleContext bundleContext) throws Exception {
debug("deactivating");
bundleContext.removeBundleListener(this);
while (!bundleWrappers.isEmpty()) {
unregister(bundleWrappers.keySet().iterator().next());
}
debug("deactivated");
this.bundleContext = null;
}
// ================================================================
// SynchronousBundleListener interface impl
// ================================================================
public void bundleChanged(BundleEvent event) {
if (event.getType() == BundleEvent.RESOLVED) {
register(event.getBundle());
} else if (event.getType() == BundleEvent.UNRESOLVED || event.getType() == BundleEvent.UNINSTALLED) {
unregister(event.getBundle().getBundleId());
}
}
protected void register(final Bundle bundle) {
debug("checking bundle " + bundle.getBundleId());
if( !isImportingUs(bundle) ) {
debug("The bundle does not import us: "+ bundle.getBundleId());
return;
}
bundleWrappers.put(bundle.getBundleId(), new BundleWrapper(bundle));
}
/**
* When bundles unload.. we remove them thier cached Class entries from the
* serviceCache. Future service lookups for the service will fail.
*
* TODO: consider a way to get the Broker release any references to
* instances of the service.
*
* @param bundleId
*/
protected void unregister(long bundleId) {
BundleWrapper bundle = bundleWrappers.remove(bundleId);
if (bundle != null) {
for (String path : bundle.cachedServices) {
debug("unregistering service for key: " +path );
serviceCache.remove(path);
}
}
}
// ================================================================
// ObjectFactory interface impl
// ================================================================
public Object create(String path) throws IllegalAccessException, InstantiationException, IOException, ClassNotFoundException {
Class clazz = serviceCache.get(path);
if (clazz == null) {
StringBuffer warnings = new StringBuffer();
// We need to look for a bundle that has that class.
int wrrningCounter=1;
for (BundleWrapper wrapper : bundleWrappers.values()) {
URL resource = wrapper.bundle.getResource(path);
if( resource == null ) {
continue;
}
Properties properties = loadProperties(resource);
String className = properties.getProperty("class");
if (className == null) {
warnings.append("("+(wrrningCounter++)+") Invalid sevice file in bundle "+wrapper+": 'class' property not defined.");
continue;
}
try {
clazz = wrapper.bundle.loadClass(className);
} catch (ClassNotFoundException e) {
warnings.append("("+(wrrningCounter++)+") Bundle "+wrapper+" could not load "+className+": "+e);
continue;
}
// Yay.. the class was found. Now cache it.
serviceCache.put(path, clazz);
wrapper.cachedServices.add(path);
break;
}
if( clazz == null ) {
// Since OSGi is such a tricky enviorment to work in.. lets give folks the
// most information we can in the error message.
String msg = "Service not found: '" + path + "'";
if (warnings.length()!= 0) {
msg += ", "+warnings;
}
throw new IOException(msg);
}
}
return clazz.newInstance();
}
// ================================================================
// Internal Helper Methods
// ================================================================
private void debug(Object msg) {
LOG.debug(msg);
}
private Properties loadProperties(URL resource) throws IOException {
InputStream in = resource.openStream();
try {
BufferedReader br = new BufferedReader(new InputStreamReader(in, "UTF-8"));
Properties properties = new Properties();
properties.load(in);
return properties;
} finally {
try {
in.close();
} catch (Exception e) {
}
}
}
private boolean isImportingUs(Bundle bundle) {
try {
// If that bundle can load our classes.. then it must be importing us.
return bundle.loadClass(Activator.class.getName())==Activator.class;
} catch (ClassNotFoundException e) {
return false;
}
}
private static class BundleWrapper {
private final Bundle bundle;
private final ArrayList<String> cachedServices = new ArrayList<String>();
public BundleWrapper(Bundle bundle) {
this.bundle = bundle;
}
}
}

7
pom.xml
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@ -400,6 +400,13 @@
<type>war</type>
</dependency>
<dependency>
<groupId>org.osgi</groupId>
<artifactId>org.osgi.core</artifactId>
<version>4.1.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.apache.hadoop.zookeeper</groupId>
<artifactId>zookeeper</artifactId>