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);

}

}