用 Java 编写的 UDP 协议简单聊天室：package com;import java.awt.*;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.awt.event.WindowAdapter;import java.awt.event.WindowEvent;import java.net.*;public class Chat {Frame frame = new Frame("个人聊天室");TextField tfip = new TextField(15);// 用户输入 IP 地址的文本框List list = new List();// 用于显示接收消息的列表框DatagramSocket ds;public Chat() {try {ds = new DatagramSocket(50000);} catch (SocketException e) {e.printStackTrace();}new Thread(new Runnable() {public void run() {try {byte buf[] = new byte[1024];DatagramPacket dp = new DatagramPacket(buf, 1024);while (true) {ds.receive(dp);System.out.println("接收 OK");list.add(new String(buf, 0, dp.getLength()) + ":from"+ dp.getAddress().getHostAddress(), 0);}} catch (Exception e) {e.printStackTrace();}}}).start();}public static void main(String[] args) {Chat chat = new Chat();chat.init();}public void init() {frame.setSize(300, 300);frame.add(list);Panel p = new Panel();p.setLayout(new BorderLayout());// p.add(tfip,"West");p.add("West", tfip);TextField tfdata = new TextField(20);p.add("East", tfdata);frame.add("South", p);frame.setVisible(true);frame.setResizable(false);// 限制用户设置窗体的大小frame.addWindowListener(new WindowAdapter() {public void windowClosing(WindowEvent e) {frame.setVisible(false);frame.dispose();System.exit(0);}});tfdata.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent e) {// 有关网络发送信息的动作byte[] buf = e.getActionCommand().getBytes();try {DatagramPacket dp = new DatagramPacket(buf, buf.length,InetAddress.getByName(tfip.getText()), 50000);ds.send(dp);} catch (Exception e1) {e1.printStackTrace();}((TextField) e.getSource()).setText("");// 清空文本框内容}});// 填写完内容后按下回车所触发的事件}}
