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);

     }

 }