简易局域网聊天室程序

近来比较闲，写了一个基于多播协议的聊天室程序。

不同于以前写的简单聊天室程序，以前的那个基于TCP协议的，重点在服务器端，客户端用Telnet即可。

本次写的程序，由于是多播/组播的情况，所以，没有服务端程序。

大致写了一个，漏洞可能较多一些，等过后再完善。

 

import java.io.IOException;import java.io.UnsupportedEncodingException;import java.net.DatagramPacket;import java.net.InetAddress;import java.net.MulticastSocket;import java.net.UnknownHostException;import java.util.Scanner;public class EasyChatRoom extends Thread{private String address = "230.0.0.1";private int port = 5000;private MulticastSocket socket;private InetAddress group;private volatile boolean running = true;private volatile String lastSendMsg = null;private ReaderThread reader;private String UID;public EasyChatRoom(String address, int port) {this.address = address;this.port = port;}public void run(){Scanner stdin = new Scanner(System.in);System.out.println("该程序，输入exit可以退出。");System.out.print("请输入您的ID:");UID = stdin.nextLine(); try{System.out.print("尝试进入聊天室...");group = InetAddress.getByName(address);socket = new MulticastSocket(port); socket.joinGroup(group); System.out.println(" [成功]"); reader = new ReaderThread();reader.start(); final String welcome = "<< "+UID+" >> 进入聊天室。"; sendMessage(welcome); while(running){ String line = stdin.nextLine(); if(line.equals("exit")){ running=false; reader.interrupt(); continue; } String message = UID+" : "+line; sendMessage(message); }}catch(IOException e){}leave();}private void leave() {final String leave = "<< "+UID+" >> 离开了聊天室。";try {sendMessage(leave);} catch (IOException e) {} try {socket.leaveGroup(group);} catch (IOException e) {}socket.close();}public static void main(String[] args) throws UnknownHostException,IOException {final EasyChatRoom room = new EasyChatRoom("230.0.0.1",5001); room.start(); Runtime.getRuntime().addShutdownHook(new Thread(){ public void run(){ room.leave(); } });}private void sendMessage(String message) throws UnsupportedEncodingException,IOException{if(message==null || message.trim().length()<=0)return;byte b [] = message.getBytes("UTF-8");DatagramPacket msg = new DatagramPacket(b,b.length, group, port);socket.send(msg);lastSendMsg=message;}class ReaderThread extends Thread { public void run() { while(running) { try { byte[] buf = new byte[1024]; DatagramPacket recv = new DatagramPacket(buf, buf.length); socket.receive(recv); String rev = new String(recv.getData(),0,recv.getLength(),"UTF-8"); if(!rev.equals(lastSendMsg)){ System.out.println(rev); } }catch(Exception ex) { } } } }}