BAEL-2174: proxies in core java (#5628)

core-java/src/main/java/com/baeldung/networking/proxies/CommandLineProxyDemo.java

@@ -0,0 +1,17 @@
+package com.baeldung.networking.proxies;
+
+import java.net.URL;
+import java.net.URLConnection;
+
+public class CommandLineProxyDemo {
+
+    public static final String RESOURCE_URL = "http://www.google.com";
+
+    public static void main(String[] args) throws Exception {
+
+        URL url = new URL(RESOURCE_URL);
+        URLConnection con = url.openConnection();
+        System.out.println(UrlConnectionUtils.contentAsString(con));
+    }
+
+}

core-java/src/main/java/com/baeldung/networking/proxies/DirectProxyDemo.java

@@ -0,0 +1,20 @@
+package com.baeldung.networking.proxies;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.Proxy;
+import java.net.URL;
+
+public class DirectProxyDemo {
+
+    private static final String URL_STRING = "http://www.google.com";
+
+    public static void main(String... args) throws IOException {
+
+        URL weburl = new URL(URL_STRING);
+        HttpURLConnection directConnection 
+          = (HttpURLConnection) weburl.openConnection(Proxy.NO_PROXY);
+        System.out.println(UrlConnectionUtils.contentAsString(directConnection));
+    }
+
+}

core-java/src/main/java/com/baeldung/networking/proxies/SocksProxyDemo.java

@@ -0,0 +1,32 @@
+package com.baeldung.networking.proxies;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.InetSocketAddress;
+import java.net.Proxy;
+import java.net.Socket;
+import java.net.URL;
+
+public class SocksProxyDemo {
+
+    private static final String URL_STRING = "http://www.google.com";
+    private static final String SOCKET_SERVER_HOST = "someserver.baeldung.com";
+    private static final int SOCKET_SERVER_PORT = 1111;
+
+    public static void main(String... args) throws IOException {
+
+        URL weburl = new URL(URL_STRING);
+        Proxy socksProxy 
+          = new Proxy(Proxy.Type.SOCKS, new InetSocketAddress("127.0.0.1", 1080));
+        HttpURLConnection socksConnection 
+          = (HttpURLConnection) weburl.openConnection(socksProxy);
+        System.out.println(UrlConnectionUtils.contentAsString(socksConnection));
+
+        Socket proxySocket = new Socket(socksProxy);
+        InetSocketAddress socketHost 
+          = new InetSocketAddress(SOCKET_SERVER_HOST, SOCKET_SERVER_PORT);
+        proxySocket.connect(socketHost);
+        // do stuff with the socket
+    }
+
+}

core-java/src/main/java/com/baeldung/networking/proxies/SystemPropertyProxyDemo.java

@@ -0,0 +1,23 @@
+package com.baeldung.networking.proxies;
+
+import java.net.URL;
+import java.net.URLConnection;
+
+public class SystemPropertyProxyDemo {
+
+    public static final String RESOURCE_URL = "http://www.google.com";
+
+    public static void main(String[] args) throws Exception {
+
+        System.setProperty("http.proxyHost", "127.0.0.1");
+        System.setProperty("http.proxyPort", "3128");
+
+        URL url = new URL(RESOURCE_URL);
+        URLConnection con = url.openConnection();
+        System.out.println(UrlConnectionUtils.contentAsString(con));
+
+        System.setProperty("http.proxyHost", null);
+        // proxy will no longer be used for http connections
+    }
+
+}

core-java/src/main/java/com/baeldung/networking/proxies/UrlConnectionUtils.java

@@ -0,0 +1,21 @@
+package com.baeldung.networking.proxies;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.URLConnection;
+
+class UrlConnectionUtils {
+
+    public static String contentAsString(URLConnection con) throws IOException {
+        StringBuilder builder = new StringBuilder();
+        try (BufferedReader reader 
+                = new BufferedReader(new InputStreamReader(con.getInputStream()))){
+            while (reader.ready()) {
+                builder.append(reader.readLine());
+            }
+        }
+        return builder.toString();
+    }
+
+}

core-java/src/main/java/com/baeldung/networking/proxies/WebProxyDemo.java

@@ -0,0 +1,23 @@
+package com.baeldung.networking.proxies;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.InetSocketAddress;
+import java.net.Proxy;
+import java.net.URL;
+
+public class WebProxyDemo {
+
+    private static final String URL_STRING = "http://www.google.com";
+
+    public static void main(String... args) throws IOException {
+
+        URL weburl = new URL(URL_STRING);
+        Proxy webProxy 
+          = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("127.0.0.1", 3128));
+        HttpURLConnection webProxyConnection 
+            = (HttpURLConnection) weburl.openConnection(webProxy);
+        System.out.println(UrlConnectionUtils.contentAsString(webProxyConnection));
+    }
+
+}