创建接受和发送UDP的socket实例

最近项目中需要用到通信这块,与上位机交互,考虑udp相对于tcp传输速度快,并且不需要三次握手,这里用了MulticastSocket来实现udp通信.

实现思路:

DatagramPacket中

第一个参数:存放数据的字节数组;第二个参数:存放数据的字节长度;第三个参数:指定链接的ip地址(IP地址的范围是224.0.0.0至239.255.255.255);第四个参数:端口号

(1)建立链接

multicastSocket.joinGroup(address);

(2)发送方法

multicastSocket.send(datagramPacket);

(3)接受方法

multicastSocket.receive(datagramPacket); // 接收数据，同样会进入阻塞状态

这里贴上客户端code:

import java.io.IOException;

import java.io.InputStream;

import java.net.DatagramPacket;

import java.net.InetAddress;

import java.net.UnknownHostException;

import java.text.SimpleDateFormat;

import java.util.Date;

public class MulticastSocket extends Thread {

static java.net.MulticastSocket multicastSocket;

public static void main(String[] args) {

try {

multicastSocket = new java.net.MulticastSocket(58432);

InetAddress address = InetAddress.getByName("234.5.6.7");

multicastSocket.joinGroup(address);

byte[] buf = new byte[1024];

while (true) {

DatagramPacket datagramPacket = new DatagramPacket(buf,

buf.length);

multicastSocket.receive(datagramPacket); // 接收数据，同样会进入阻塞状态

byte[] message = new byte[datagramPacket.getLength()]; // 从buffer中截取收到的数据

System.arraycopy(buf, 0, message, 0, datagramPacket.getLength());

System.out.println(datagramPacket.getAddress());

System.out.println(new String(message));

}

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

} // 接收数据时需要指定监听的端口号

}

public void run() {

// TODO Auto-generated method stub

while (true) {

byte[] buf = new byte[1024];

DatagramPacket datagramPacket;

try {

datagramPacket = new DatagramPacket(buf, buf.length,

InetAddress.getByName("234.5.6.7"), 58432);

multicastSocket.send(datagramPacket);

// multicastSocket.close();

} catch (UnknownHostException e1) {

// TODO Auto-generated catch block

e1.printStackTrace();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}

}