multicastserver.java

服务器端程序将dat.txt中的内容不断的向局域网内广播, 客户端程序接收局域网内的广播内容.

import java.io.*;
import java.net.*;
import java.util.*;
public class MulticastServer{
	public static void main(String args[]) throws java.io.IOException{
		new MulticastServerThread().start(); 
		//启动一个服务器线程
	}
}
class MulticastServerThread extends Thread{ 
	DatagramSocket socket;
	DatagramPacket packet;
	InetAddress group;
	BufferedReader bf;
	
	//private boolean token=true;
	private long FIVE_SECONDS=5000; //定义常量，5秒钟
	public MulticastServerThread() throws IOException{

		this("MulticastServerThread");
		//调用父类，也就是QuoteServerThread的构造函数
	}
	public MulticastServerThread(String name){
		super(name);
		try{
			socket=new DatagramSocket(4001);
			group=InetAddress.getByName("230.0.0.1");
		}catch(Exception e){}
		try{
			bf=new BufferedReader(new FileReader("data.txt"));
		}catch(Exception e){System.out.println("File not found!");}
		 
	}
	
	public void run() //重写父类的线程主体
	{	
		int count=0;
		String allData="";
		boolean token=true;
		try{
			String line=bf.readLine();
			while(line!=null){
				allData+=line+"\n";
				line=bf.readLine();
			}
			while(token){
				try{
					byte [] data=allData.getBytes();
					packet=new DatagramPacket(data,data.length,group,4001);
					socket.send(packet);
						
					System.out.println(count=count+1);
					try{
						sleep((long)(Math.random()*FIVE_SECONDS));
					}catch(Exception e){}
					if(count>20) token=false;
				}catch(Exception e){}
			}
			socket.close();
			bf.close();		
		}catch(Exception e){}
	}
}