Add callback server class.

framework/src/com/phonegap/CallbackServer.java

@@ -0,0 +1,224 @@
+package com.phonegap;
+
+import java.io.BufferedReader;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.util.LinkedList;
+
+/**
+ * This class provides a way for Java to run JavaScript in the web page that has loaded PhoneGap.
+ * The CallbackServer class implements an XHR server and a list of JavaScript statements
+ * that are to be executed on the web page.
+ * 
+ * The process flow is:
+ * 1. JavaScript makes an async XHR call. 
+ * 2. The server holds the connection open until data is available. 
+ * 3. The server writes the data to the client and closes the connection. 
+ * 4. The server immediately starts listening for the next XHR call. 
+ * 5. The client receives this XHR response, processes it.
+ * 6. The client sends a new async XHR request.
+ *
+ */
+public class CallbackServer implements Runnable {
+	
+	/**
+	 * The list of JavaScript statements to be sent to JavaScript.
+	 */
+	private LinkedList<String> javascript;
+	
+	/**
+	 * The port to listen on.
+	 */
+	private int port;
+	
+	/**
+	 * The server thread.
+	 */
+	private Thread serverThread;
+	
+	/**
+	 * Indicates the server is running.
+	 */
+	private boolean active;
+	
+	/**
+	 * Indicates that the JavaScript statements list is empty
+	 */
+	private boolean empty;
+	
+	/**
+	 * Constructor.
+	 */
+	public CallbackServer() {
+		//System.out.println("CallbackServer()");
+		this.active = false;
+		this.empty = true;
+		this.port = 0;
+		this.javascript = new LinkedList<String>();
+		this.startServer();
+	}
+	
+	/**
+	 * Get the port that this server is running on.
+	 * 
+	 * @return
+	 */
+	public int getPort() {
+		return this.port;
+	}
+	
+	/**
+	 * Start the server on a new thread.
+	 */
+	public void startServer() {
+		//System.out.println("CallbackServer.startServer()");
+		this.active = false;
+		
+		// Start server on new thread
+		this.serverThread = new Thread(this);
+		this.serverThread.start();
+	}
+
+	/**
+	 * Restart the server on a new thread.
+	 */
+	public void restartServer() {
+		
+		// Stop server
+		this.stopServer();
+				
+		// Start server again
+		this.startServer();
+	}
+
+	/**
+	 * Start running the server.  
+	 * This is called automatically when the server thread is started.
+	 */
+	public void run() {
+		
+		// Start server
+		try {
+			this.active = true;
+			String request;
+			ServerSocket waitSocket = new ServerSocket(0);
+			this.port = waitSocket.getLocalPort();
+			//System.out.println(" -- using port " +this.port);
+
+			 while (this.active) {
+				 //System.out.println("CallbackServer: Waiting for data on socket");
+				 Socket connection = waitSocket.accept();
+				 BufferedReader xhrReader = new BufferedReader(new InputStreamReader(connection.getInputStream()),40);
+				 DataOutputStream output = new DataOutputStream(connection.getOutputStream());
+				 request = xhrReader.readLine();
+				 //System.out.println("Request="+request);
+				 if(request.contains("GET"))
+				 {
+					 //System.out.println(" -- Processing GET request");
+					 
+					 // Wait until there is some data to send, or send empty data every 30 sec 
+					 // to prevent XHR timeout on the client 
+					 synchronized (this) { 
+						 while (this.empty) { 
+							 try { 
+								 this.wait(30000); // prevent timeout from happening
+								 //System.out.println(">>> break <<<");
+								 break;
+							 } 
+							 catch (Exception e) { }
+						 } 
+					 }
+					 
+					 // If server is still running
+					 if (this.active) {
+					
+						 // If no data, then send 404 back to client before it times out
+						 if (this.empty) {
+							 //System.out.println(" -- sending data 0");
+							 output.writeBytes("HTTP/1.1 404 NO DATA\r\n\r\n");
+						 }
+						 else {
+							 //System.out.println(" -- sending item");
+							 output.writeBytes("HTTP/1.1 200 OK\r\n\r\n"+this.getJavascript());
+						 }
+					 }					 
+				 }
+				 //System.out.println("CallbackServer: closing output");
+				 output.close();				 
+			 }
+		 } catch (IOException e) {
+			 e.printStackTrace();
+		 }
+		 this.active = false;
+		 //System.out.println("CallbackServer.startServer() - EXIT");
+	}
+		
+	/**
+	 * Stop server.  
+	 * This stops the thread that the server is running on.
+	 */
+	public void stopServer() {
+		//System.out.println("CallbackServer.stopServer()");
+		this.active = false;
+
+		// Break out of server wait
+		synchronized (this) { 
+			this.notify();
+		}		
+	}
+
+    /**
+     * Destroy
+     */
+    public void destroy() {
+    	this.stopServer();
+    }
+
+	/**
+	 * Get the number of JavaScript statements.
+	 * 
+	 * @return int
+	 */
+	public int getSize() {
+		int size = this.javascript.size();
+		//System.out.println("getSize() = " + size);
+		return size;
+	}
+	
+	/**
+	 * Get the next JavaScript statement and remove from list.
+	 *  
+	 * @return String
+	 */
+	public String getJavascript() {
+		if (this.javascript.size() == 0) {
+			return null;
+		}
+		String statement = this.javascript.remove(0);
+		//System.out.println("CallbackServer.getJavascript() = " + statement);
+		if (this.javascript.size() == 0) {
+			synchronized (this) { 
+				this.empty = true;
+			}
+		}
+		return statement;
+	}
+	
+	/**
+	 * Add a JavaScript statement to the list.
+	 * 
+	 * @param statement
+	 */
+	public void sendJavascript(String statement) {
+		//System.out.println("CallbackServer.sendJavascript("+statement+")");
+		this.javascript.add(statement);
+		synchronized (this) { 
+			this.empty = false;
+			this.notify();
+		}
+	}
+	
+}