JavaSocket UDP Byte类型的收发

package  com.zchome;

import  java.net. * ;
import  java.io. * ;

public   class  testudp {
     public   static   void  main(String[] args) {
        DatagramSocket s  =   null ;
         try  {
            s  =   new  DatagramSocket();
             byte [] control_buffer  =   new   byte [ 4 ];
             byte [] content_buffer  =   null ;
             byte [] result_buffer  =   null ;
             byte [] receive_buffer  =   new   byte [ 100 ];
             for  ( int  nloopindex  =   0 ; nloopindex  <   10 ; nloopindex ++ ) {
                 // define first 4 Bytes
                control_buffer[ 0 ]  =   0x00 ;
                control_buffer[ 1 ]  =   0x01 ;
                control_buffer[ 2 ]  =   0x01 ;
                control_buffer[ 3 ]  =   0x00 ;
                
                String IPAddress  =   " 192.168.0.2 " ;
                content_buffer  =  IPAddress.getBytes();
                
                result_buffer  =  Toolkit.getInstance().addByteBuffers(control_buffer, content_buffer);
                
                InetAddress ia  =  InetAddress.getByName( " 192.168.0.9 " );
                
                DatagramPacket dgp  =   new  DatagramPacket(result_buffer, result_buffer.length, ia,  10002 );
                s.send(dgp);
                
                dgp  =   new  DatagramPacket(receive_buffer, receive_buffer.length, ia,  10002 );
                s.receive(dgp);
                System.out.println( new  String(dgp.getData()));
            }
        }
         catch  (IOException e) {
            System.out.println(e.toString());
        }
         finally  {
             if  (s  !=   null )
                s.close();
        }
    }
}

 

这里还有一个将两个byte数组相加的方法：  

/*
* Toolkit.java
*
* Created on 2004年8月18日, 上午10:53
*/

package  com.zchome;

/**
*
*  @author   张超
*/
public   class  Toolkit {
    
     /**  Creates a new instance of Toolkit  */
     private  Toolkit() {
    }
    
     private   static  Toolkit _instance  =   null ;
    
     public   static  Toolkit getInstance() {
         if  (_instance  ==   null )
            _instance  =   new  Toolkit();
         return  _instance;
    }
    
     public   byte [] addByteBuffers( byte [] first,  byte [] second)
    {
         int  nloopindex  =   0 ;
         int  first_length  =  first.length;
         int  second_length  =  second.length;
         byte [] return_bytes  =   new   byte [first_length  +  second_length];
        
         for  (nloopindex  =   0 ; nloopindex  <  first_length; nloopindex ++ )
        {
            return_bytes[nloopindex]  =  first[nloopindex];
        }
         for  (nloopindex  =   0 ; nloopindex  <  second_length; nloopindex ++ )
        {
            return_bytes[first_length  +  nloopindex]  =  second[nloopindex];
        }
        
         return  return_bytes;
    }
    
}

 

 

 一点注意：在s.receive一句之前加上这句： 

socket.setSoTimeout(5000); //设置5秒的timeout 

这样可以防止，在没有东西receive的时候，程序被block