简单聊天程序

本程序实现任意两个已知IP的两电脑之间的聊天通讯。

Chat.java代码如下：

package com.chat.app;

import java.awt.BorderLayout;
import java.awt.Frame;
import java.awt.List;
import java.awt.Panel;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;

public class Chat extends Frame{

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	List list = new List(6);
	//定义列表框，最多显示6行
	TextField tfIP = new TextField(15);
	TextField tfData = new TextField(20);
	DatagramSocket ds  = null;
	public Chat(){
		try {
			ds = new DatagramSocket(3000);
			//设置自己接收数据的端口号为3000
		} catch (SocketException e1) {
			e1.printStackTrace();
		}

		this.add(list,"Center");
		Panel p = new Panel();
		this.add(p,"South");
		p.setLayout(new BorderLayout());
		p.add(tfIP,"West");
		p.add(tfData,"East");

		/**
		 * 接收数据处理代码
		 */
		new Thread(new Runnable(){
			public void run(){
				byte[] buf = new byte[1024];
				DatagramPacket dp = new DatagramPacket(buf,buf.length);
				while(true){
					try {
						ds.receive(dp);
					} catch (IOException e) {
						if(!ds.isClosed()){
							//只有当程序没有被关闭时，发生异常才会抛出异常
							e.printStackTrace();
						}
					}
					list.add(new String(buf,0,dp.getLength())+" from "+dp.getAddress().getHostAddress()+":"+dp.getPort(),0);
				}
			}
		}).start();

		/**
		 * 网络消息发送处理代码
		 */
		tfData.addActionListener(new ActionListener() {

			public void actionPerformed(ActionEvent e) {
				//取出消息文本框中的数据和ip文本框中的IP地址
				byte[] buf = tfData.getText().getBytes();

				try {
					DatagramPacket dp = new DatagramPacket(buf, buf.length,InetAddress.getByName(tfIP.getText()),3000);
					//这里设置接收消息的端口号为3000
					ds.send(dp);
					//如果将ds.send(dp);语句放到try语句块外面，则访问不到dp了，因为dp的有效范围为try语句块内
				} catch (UnknownHostException e1) {
					e1.printStackTrace();
				} catch (IOException e1) {
					e1.printStackTrace();
				}
				tfData.setText("");
			}
		});
		addWindowListener(new WindowAdapter() {
			public void windowClosing(WindowEvent e){
				ds.close();
				dispose();
				System.exit(0);
			}
		});
	}

	public static void main(String[] args) {

		System.out.println("Starting chat...");
		Chat mainFrame = new Chat();
		mainFrame.setSize(300, 400);
		mainFrame.setTitle("Chat");
		mainFrame.setVisible(true);
		mainFrame.setResizable(false);
	}

}

运行结果如下：