Java使用UDP聊天程序

主要想测试Java UDP通信。Java UDP使用DatagramSocket和DatagramPacket完成UDP通信

主要思路：

1.本机通信，ip地址为：127.0.0.1

2.开一个线程监听一个端口

3.向端口发送消息

4.运行程序java ChatWindow desport listenport

ChatWindow.java

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.util.Scanner;

/**
 * 聊天小程序
 * 使用UDP进行通信
 * 开一个线程，监听一个端口，接收消息
 * 这里主要用于本机通信，IP为127.0.0.1
 * 
 * 发送消息正常，接收消息没反应
 * @author GXF
 *
 */
public class ChatWindow {
    private int listenPort;                    //监听端口
    private int desPort;                    //目标端口
    
    /**
     * 初始化目的端口和监听端口
     * @param desPort
     * @param listenPort
     */
    public ChatWindow(int desPort, int listenPort){
        this.desPort = desPort;
        this.listenPort = listenPort;
        
        //启动监听线程
        Thread listenMessageThread = new Thread(new ReceiveMessage());
        listenMessageThread.start();
        
        System.out.println("程序已启动，愉快的开始聊天吧！");
        //接收用户输入的消息
        Scanner scanner = new Scanner(System.in);
        while(true){
            String message = scanner.nextLine();
            sendMessag(message);
        }
    }
    
    /**
     * 向目的端口发送一个消息
     * @param message
     */
    public void sendMessag(String message){
        //初始化一个socket
        //设置好数据包
        //发送消息
        try {
            DatagramSocket socketToSendMessage = new DatagramSocket();
            byte buff[] = message.getBytes();
            DatagramPacket packetToSend = new DatagramPacket(buff, buff.length, InetAddress.getByName("127.0.0.1"), desPort);
            socketToSendMessage.send(packetToSend);                                         //发送消息
            socketToSendMessage.close();                                                    //关闭socket
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    
    /**
     * 监听端口线程
     * 实例化一个DatagramSocket，并绑定一个端口进行监听
     * @author GXF
     *
     */
    class ReceiveMessage implements Runnable{
        private DatagramSocket listenSocket;
        private DatagramPacket receivePacket;
        private byte buff[] = new byte[1024];
        @Override
        public void run() {
            //init
            init();
            //start 监听
            while(true){
                try {
                    listenSocket.receive(receivePacket);                    //接收数据包
                    String receiveMessage = new String(receivePacket.getData(), 0, receivePacket.getLength());
                    System.out.println(receiveMessage);                        //输出接收到的消息
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            
        }
        
        /**
         * 对socket，端口,进行初始化
         */
        public void init(){
            try {                
                InetSocketAddress serverSocketAddress = new InetSocketAddress(listenPort);
                listenSocket = new DatagramSocket(serverSocketAddress);    
                receivePacket = new DatagramPacket(buff, buff.length);                
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) {
        if(args.length != 2)
        {
            System.out.println("usage: java ChatWindow desport listenport");
            return;
        }
        int desport = Integer.valueOf(args[0]);
        int listenPort = Integer.valueOf(args[1]);
        //first is desport, seconde is listenport
        ChatWindow chatWindow = new ChatWindow(desport, listenPort);
        

    }

}