udpclient.java

疯狂Java讲义_源码(含Java设计模式CHM

import java.awt.*;
import java.net.*;
import java.io.*;
import java.util.*;

/**
 * Description:
 * <br/>Copyright (C), 2008-2010, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee [e-mail]
 * @version  1.0
 */
public class UdpClient
{
	//定义发送数据报的目的地
	public static final int DEST_PORT = 30000;
	public static final String DEST_IP = "127.0.0.1";

	//定义每个数据报的最大大小为4K
	private static final int DATA_LEN = 4096;
	//定义该客户端使用的DatagramSocket
	private DatagramSocket socket = null;
	//定义接收网络数据的字节数组
	byte[] inBuff = new byte[DATA_LEN];
	//以指定字节数组创建准备接受数据的DatagramPacket对象
	private DatagramPacket inPacket = 
		new DatagramPacket(inBuff , inBuff.length);
	//定义一个用于发送的DatagramPacket对象
	private DatagramPacket outPacket = null;
	public void init()throws IOException
	{
		try
		{
			//创建一个客户端DatagramSocket，使用随机端口
			socket = new DatagramSocket();
			//初始化发送用的DatagramSocket，它包含一个长度为0的字节数组
			outPacket = new DatagramPacket(new byte[0] , 0 ,
				InetAddress.getByName(DEST_IP) , DEST_PORT);
			//创建键盘输入流
			Scanner scan = new Scanner(System.in);
			//不断读取键盘输入
			while(scan.hasNextLine())
			{
				//将键盘输入的一行字符串转换字节数组
				byte[] buff = scan.nextLine().getBytes();
				//设置发送用的DatagramPacket里的字节数据
				outPacket.setData(buff);
				//发送数据报
				socket.send(outPacket);
				//读取Socket中的数据，读到的数据放在inPacket所封装的字节数组里。
				socket.receive(inPacket);
				System.out.println(new String(inBuff , 0 , 
					inPacket.getLength()));
			}
		}
		//使用finally块保证关闭资源
		finally
		{
			if (socket != null)
			{
				socket.close();
			}
		}
	}

	public static void main(String[] args) 
		throws IOException
	{
		new UdpClient().init();
	}
}