From 615d86fa2804aea689aded9634918a69a9bab855 Mon Sep 17 00:00:00 2001
From: "M.Scholz" <m.scholz88@onlinehome.de>
Date: Thu, 1 Nov 2012 12:56:08 +0100
Subject: [PATCH] included java nio (channel and buffer system)

---
 .../uebungen/2/p2p_ex2/src/NetworkStack.java  | 68 +++++++++++--------
 1 file changed, 38 insertions(+), 30 deletions(-)

diff --git a/GIT/P2P/uebungen/2/p2p_ex2/src/NetworkStack.java b/GIT/P2P/uebungen/2/p2p_ex2/src/NetworkStack.java
index 6d4bcdbb..10664db2 100644
--- a/GIT/P2P/uebungen/2/p2p_ex2/src/NetworkStack.java
+++ b/GIT/P2P/uebungen/2/p2p_ex2/src/NetworkStack.java
@@ -1,11 +1,19 @@
+package u1;
+
 import java.io.IOException;
 import java.net.DatagramPacket;
 import java.net.DatagramSocket;
 import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.net.SocketAddress;
 import java.net.SocketException;
+import java.nio.ByteBuffer;
+import java.nio.channels.DatagramChannel;
 import java.util.EmptyStackException;
 import java.util.Stack;
 
+import javax.sound.sampled.ReverbType;
+
 /* Truncated messages (happens after 1024 bytes) are not handled as such by the server.
  * 
  * 
@@ -19,47 +27,49 @@ import java.util.Stack;
  */
 
 class NetworkStack {
-	private DatagramSocket serverSocket;
-
+	//private DatagramSocket serverSocket;
+	
+	private DatagramChannel channel;
+	
 	protected static final byte CMD_PUSH = '0';
 	protected static final byte CMD_POP = '1';
 	protected static final byte CMD_PRINT = '2';
 
 	private Stack<String> stack;
-	private byte[] inBuffer = new byte[1024];
-	private byte[] outBuffer = new byte[1024];
 
-	public NetworkStack(final int port) throws SocketException {
-		serverSocket = new DatagramSocket(port);
+	public NetworkStack(final int port) throws IOException {
+		
 		stack = new Stack<String>();
-		DatagramPacket receivePacket;
+		
+		channel = DatagramChannel.open();
+		channel.socket().bind(new InetSocketAddress(port));
+		
+		ByteBuffer buf = ByteBuffer.allocate(1024);
+		buf.clear();
+
 
 		while (true) {
-			receivePacket = new DatagramPacket(inBuffer, inBuffer.length);
+			SocketAddress client = channel.receive(buf); // write stuff from channel to buffer
 
-			try {
-				serverSocket.receive(receivePacket);
-			} catch (IOException e) {
-				e.printStackTrace();
-			}
+			buf.flip(); // make buffer readable
+			
+			byte[] receivedData = buf.array();
 
-			byte[] receivedData = receivePacket.getData();
 			byte messageType = receivedData[0];
-			String received = new String(receivePacket.getData()).trim();
+			String received = new String(receivedData.toString().trim());
+			
 
 			switch (messageType) {
 			case CMD_PUSH:
 				String value = new String(receivedData).substring(1).trim();
 				stack.push(value);
-
 				System.out.println("Push " + value);
 				break;
 
 			case CMD_POP:
 				try {
 					String popped = stack.pop() + '\n';
-					send(popped, receivePacket.getAddress(),
-							receivePacket.getPort());
+					send(popped, client);
 					System.out.println("Pop " + popped);
 				} catch (EmptyStackException e) {
 					System.out.println("Received pop but stack is empty");
@@ -74,36 +84,34 @@ class NetworkStack {
 				}
 				result.append('\n');
 
-				send(result.toString(), receivePacket.getAddress(),
-						receivePacket.getPort());
+				send(result.toString(), client);
 				break;
 
 			default:
 				System.out.println("Received unknown command: " + "["
 						+ received + "]");
 				break;
+		
 			}
-			inBuffer = new byte[1024];
+			
+			buf.clear(); //clear buffer and make it ready to write
 		}
 	}
 
-	private void send(String text, InetAddress addr, int port) {
-		outBuffer = text.getBytes();
-
-		DatagramPacket sendPacket = new DatagramPacket(outBuffer,
-				outBuffer.length, addr, port);
-
+	private void send(String text, SocketAddress client) {
 		try {
-			serverSocket.send(sendPacket);
+			channel.send(ByteBuffer.wrap(text.getBytes()), client);
 		} catch (IOException e) {
+			// TODO Auto-generated catch block
 			e.printStackTrace();
 		}
+		
 	}
 
 	public static void main(String args[]) {
 		try {
-			new NetworkStack(9999);
-		} catch (SocketException e) {
+			new NetworkStack(1234);
+		} catch (IOException e) {
 			e.printStackTrace();
 		}
 	}