服务器客户端java

我想让我的服务器能够接受来自两个客户端的消息。但出了点问题。需要帮助！我试图运行同一个客户端两次，但只收到一条消息和一些错误。服务器客户端java

import java.io.IOException; 
import java.net.DatagramPacket; 
import java.net.DatagramSocket; 
import java.net.InetAddress; 

public class Serv1 { 
public static void main(String[] args) throws IOException { 

     Listner listner = new Listner(); 
     Thread thread = new Thread(listner); 
     thread.start(); 

     System.out.println("thread already started"); 

     DatagramSocket s = new DatagramSocket(8787); 

     byte[] receiveData = new byte[1024]; 

     System.out.println ("Waiting for datagram packet"); 

     DatagramPacket p = new DatagramPacket(receiveData, receiveData.length); 

     System.out.println("about to receive packet N1"); 
     s.receive(p); 

     String sentence = new String(p.getData()); 
     InetAddress IPAddress = p.getAddress(); 
     int port = p.getPort(); 

     System.out.println ("From: " + IPAddress + ":" + port); 
     System.out.println ("Message: " + sentence); 



     try { 
      Thread.sleep(1000); 
     } catch (InterruptedException e) { 
      Thread.currentThread().interrupt(); 
      e.printStackTrace(); 
     } 

     receiveData = new byte[1024]; 

     System.out.println ("Waiting for datagram packet"); 
     p = new DatagramPacket(receiveData, receiveData.length); 

     System.out.println("about to receive packet N2"); 

     s.receive(p); 
     sentence = new String(p.getData()); 
     IPAddress = p.getAddress(); 
     port = p.getPort(); 
} 

} 


class Listner implements Runnable 
    { 

     public void run() { 
     String text = null; 
     while(true){ 
      text = null;  
     int server_port = 8787; 

     byte[] receiveData = new byte[1024]; 
     DatagramPacket p = new DatagramPacket(receiveData, receiveData.length); 
     DatagramSocket s = null; 
     try{ 
      s = new DatagramSocket(server_port); 
     }catch (SocketException e) { 
      e.printStackTrace(); 
      System.out.println("Socket excep, port used"); 
     } 
     try { 
     s.receive(p); 
     }catch (IOException e) { 
      e.printStackTrace(); 
       System.out.println("IO EXcept"); 
      } 
     text = new String(receiveData, 0, p.getLength()); 
     System.out.println("message = "+text); 
     s.close(); 

    } 
} 

}

运行：

线程已经开始

等待数据报包即将接收数据包N1

java.net.BindException: Address already in use: Cannot bind 
    at java.net.PlainDatagramSocketImpl.bind0(Native Method) 
    at java.net.PlainDatagramSocketImpl.bind(PlainDatagramSocketImpl.java:91) 
    at java.net.DatagramSocket.bind(Socket excep, port used 
DatagramSocket.java:372) 
    at java.net.DatagramSocket.<init>(DatagramSocket.java:211) 
    at java.net.DatagramSocket.<init>(DatagramSocket.java:262) 
    at java.net.DatagramSocket.<init>(DatagramSocket.java:235) 
    at serv1.Listner.run(Listner.java:29) 
    at java.lang.Thread.run(Thread.java:662) 
Exception in thread "Thread-0" java.lang.NullPointerException 
    at serv1.Listner.run(Listner.java:35) 
    at java.lang.Thread.run(Thread.java:662) 
From: /192.168.1.102:58977 
Message: hi, i am the first one 
Waiting for datagram packet 
about to receive packet N2 
BUILD SUCCESSFUL (total time: 59 seconds)**strong text**

来源

2013-04-11 chajka

您正试图在同一端口绑定的两倍。这不是它的工作原理。您应该有1个线程侦听端口，并有一个线程池来处理请求。每当有新信息出现时，您就会将请求数据（收到的新信息）提供给线程进行处理。

来源

2013-04-11 00:30:34 mvallebr

您正在创建2 DatagramSocket'同一个端口（8787）。一种是在主要方法中创建的，另一种是在Listner内部类'run()方法中创建的。

我不知道你想在这里做什么，但您可能需要运行不同的端口上Listner类的DatagramSocket类或路过的main()方法将Listner类创建的一个。

来源

2013-04-11 00:30:54

服务器客户端java

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