java使用UDP协议传输数据

http://blog.csdn.net/awj3584/article/details/24714515

UDP协议（User Datagram Protocol,用户数据报协议）不同于TCP协议，它是不可能靠的，但是它比TCP协议具有更快的传输速度，UDP发送的数据单元称为数据报，当网络传输UDP传输UDP数据报是无法保证数据能够到达目的地，也无法保证按发送的顺序到达目的地，也就是说先发送了“hello”,再发送了“world”,但接收方可能会先收到“world”,再收到“hello”,也有可能收不到数据，为什么呢？因为它是不可能靠的，在传输途中可能丢失了。但UDP比TCP跟适合与传输实时音频。下面是一个简单的UPD传输数据报的例子

服务器端：

[java] view
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import java.io.IOException;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.SocketException;

public class EchoServer {

private DatagramSocket datagramSocket;

private final int port = 8088;

public static void main(String[] args) throws SocketException {

new EchoServer().service();

}

public EchoServer() throws SocketException{

datagramSocket = new DatagramSocket(port);

System.out.println("服务器启动");

}

public String echo(String msg){

return "echo:"+msg;

}

public void service(){

while (true) {

try {

DatagramPacket packet = new DatagramPacket(new byte[512], 512);

datagramSocket.receive(packet);

String msg = new String(packet.getData(), 0, packet.getLength());

System.out.println(packet.getAddress()+"/"+packet.getPort()+" msg:"+msg);

packet.setData(echo(msg).getBytes());

datagramSocket.send(packet);

} catch (IOException e) {

e.printStackTrace();

}

}

}

}

客户端：

[java] view
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import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.InetAddress;

import java.net.SocketException;

public class EchoClient {

private String remoteHost="localhost";

private int remotePort=8088;

private DatagramSocket datagramSocket;

public EchoClient() throws SocketException{

datagramSocket = new DatagramSocket();

}

public static void main(String[] args) throws SocketException {

new EchoClient().talk();

}

public void talk(){

try {

BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

String msg = null;

InetAddress address = InetAddress.getByName(remoteHost);

while ((msg=reader.readLine())!=null) {

//发送数据报

byte [] buffer = msg.getBytes();

DatagramPacket packet = new DatagramPacket(buffer,buffer.length, address, remotePort);

datagramSocket.send(packet);

//接收数据报

DatagramPacket inputPacket = new DatagramPacket(new byte[512], 512);

datagramSocket.receive(inputPacket);

System.out.println(new String(inputPacket.getData(), 0 , inputPacket.getLength()));

if("bye".equals(msg)){

break;

}

}

} catch (IOException e) {

e.printStackTrace();

}finally{

datagramSocket.close();

}

}

}