server.java

JAVA的nat 穿透的实现

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;



public class server {

	/**
	 * @param args
	 */
	static InetAddress clientIP1,clientIP2;
	static int clientPort1,clientPort2;
	public static void main(String[] args) {
		// TODO Auto-generated method st
		try {
			byte[] inbuf = new byte[256]; 
			 DatagramSocket server = new DatagramSocket(8888);
			 DatagramPacket packet = new DatagramPacket(inbuf, inbuf.length);
			System.out.print("server is running!");
			 while(true){
			 server.receive(packet);
			 System.out.print("receive "+new String(packet.getData()));
		if(new String(packet.getData()).startsWith("login1"))
			 {
			clientIP1=packet.getAddress();
			clientPort1=packet.getPort();
			System.out.print("receive client1");
			 }
		else if(new String(packet.getData()).startsWith("login2"))
			{
			clientIP2=packet.getAddress();
			clientPort2=packet.getPort();
			System.out.print("receive client2");
			byte[] data=(clientIP1.toString()+":"+clientPort1).getBytes();
			DatagramPacket request = new DatagramPacket(data, data.length,packet.getAddress(), packet.getPort());
		    server.send(request);
		    data=(clientIP2.toString()+":"+clientPort2).getBytes();
		    request = new DatagramPacket(data, data.length,clientIP1, clientPort1);
		    server.send(request);
		}
		
			 }
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}