java多线程网络编程

　　服务器要同时维护多个连接，就要用到多线程。当accept()收到一个连接请求，就新建一个socket，然后把它交给一条新线程处理。

　　那么主线程怎么知道其他线程结束了呢？

　　可以通过用join()方法等待线程结束。thread_1.join()表示要等thread_1结束才执行后面的语句。

      把新建的线程放进一个容器里，然后逐个使用join()，主线程就可以等待子线程结束才继续执行。

　　　　

import java.io.*;
import java.net.*;
import java.util.ArrayList;
import java.util.Iterator;

public class MultiThreadServer {
    static int portNum=10000;
    static int counter=0;
    public static void main(String[] args) throws IOException, InterruptedException{
        ServerSocket server_socket=new ServerSocket(portNum);
        System.out.println("Server has been started:"+server_socket);
        ArrayList<MultiThreadSocket> list=new ArrayList<MultiThreadSocket>();
        do{
            Socket socket= server_socket.accept();
            System.out.println("Accept the client:"+socket);
            MultiThreadSocket thread=new MultiThreadSocket(socket);
            thread.start();    
            list.add(thread);
            counter++;
        }while(counter<3);
        server_socket.close();
        System.out.println("Server has been closed");
        Iterator<MultiThreadSocket> it=list.iterator();
        while(it.hasNext()){
            MultiThreadSocket t=(MultiThreadSocket) it.next();
            t.join();
        }    
    }
}

 

public class MultiThreadSocket  extends Thread {
    Socket socket;
    BufferedReader in;
    PrintWriter out;    
    MultiThreadSocket(Socket socket) throws IOException{
        this.socket=socket;
        in=new BufferedReader(new InputStreamReader(socket.getInputStream()));
        out=new PrintWriter(socket.getOutputStream(),true);
    }
    public void run() {
        try{
            sleep(15000);
            while(true){
                String str=in.readLine();
                if(str.equals("Bye")){
                    out.println("Bye");
                    break;
                }
                System.out.println("Received message:"+str);
                out.println("Received message:"+str);
            }
            socket.close();
        }
        catch(IOException e){} catch (InterruptedException e) {}    
    }    
}