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