Java UDP网络编程 简单实例

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服务端代码

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

class UDPServer {

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

        DatagramSocket server = new DatagramSocket(5050);//指定服务器端口号

        //接收
        byte[] recvBuf = new byte[100];
        DatagramPacket recvPacket = new DatagramPacket(recvBuf, recvBuf.length);//接收来自客户端的数据
        server.receive(recvPacket);

        String recvStr = new String(recvPacket.getData(), 0,
                recvPacket.getLength());
        System.out.println("服务端收到：" + recvStr);

        //发送
        int port = recvPacket.getPort();
        InetAddress addr = recvPacket.getAddress();
        String sendStr = "Hello ! I'm Server";
        byte[] sendBuf;
        sendBuf = sendStr.getBytes();
        DatagramPacket sendPacket = new DatagramPacket(sendBuf, sendBuf.length,
                addr, port);
        server.send(sendPacket);

        server.close();
    }
}

客户端代码

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

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

        DatagramSocket client = new DatagramSocket();

        //发送
        String sendStr = "Hello! I'm Client";
        byte[] sendBuf;
        sendBuf = sendStr.getBytes();
        InetAddress addr = InetAddress.getByName("127.0.0.1");
        int port = 5050;
        DatagramPacket sendPacket = new DatagramPacket(sendBuf, sendBuf.length,
                addr, port);
        client.send(sendPacket);

        //接收
        byte[] recvBuf = new byte[100];
        DatagramPacket recvPacket = new DatagramPacket(recvBuf, recvBuf.length);
        client.receive(recvPacket);
        String recvStr = new String(recvPacket.getData(), 0,
                recvPacket.getLength());
        System.out.println("客户端收到:" + recvStr);
        client.close();
    }
}

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测试结果