UDP通信例子

服务端：

package com.socket.udp;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketException;

/**
 * 基于UDP协议通信，服务端程序。
 */
public class Server
{
    private DatagramSocket server = null;
    private InetSocketAddress addr = null;
    private final byte[] buffer = new byte[256];
    private DatagramPacket packet = null;

    public Server(String host, int port) throws SocketException
    {
        this.addr = new InetSocketAddress(host, port);
        this.server = new DatagramSocket(this.addr);
        System.out.println("服务端开启");
    }

    /**
     * 接收
     */
    public String receive() throws IOException
    {
        this.packet = new DatagramPacket(this.buffer, this.buffer.length);
        this.server.receive(this.packet);
        return new String(this.packet.getData(), 0, this.packet.getLength());
    }

    /**
     * 发送
     */
    public DatagramPacket response(String info) throws IOException
    {
        DatagramPacket p = new DatagramPacket(this.buffer, this.buffer.length, this.packet.getAddress(), this.packet.getPort());
        p.setData(info.getBytes());
        this.server.send(p);
        return p;
    }

    public static void main(String[] args) throws IOException
    {
        String serverHost = "127.0.0.1";
        int serverPort = 10000;
        Server server = new Server(serverHost, serverPort);
        while (true)
        {
            System.out.println("服务端接收到:" + server.receive());
            server.response("server说：客户端你好！");
        }
    }

}

客户端：

package com.socket.udp;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;

/**
 *  基于UDP协议通信，客户端程序。
 */
public class Client
{
    private DatagramSocket client = null;
    private DatagramPacket packet = null;
    private final byte[] buffer = new byte[1024];

    public Client(String host, int port, byte[] bytes) throws SocketException, UnknownHostException
    {
        this.client = new DatagramSocket();
        this.packet = new DatagramPacket(bytes, bytes.length, InetAddress.getByName(host), port);
        System.out.println("客户端开启");
    }

    /**
     * 发送
     */
    public DatagramPacket send() throws IOException
    {
        this.client.send(this.packet);
        return this.packet;
    }

    /**
     * 接收
     */
    public String receive(String host, int port) throws IOException
    {
        DatagramPacket p = new DatagramPacket(this.buffer, this.buffer.length, InetAddress.getByName(host), port);
        this.client.receive(p);
        return new String(p.getData());
    }

    public String receive2() throws IOException
    {
        DatagramPacket p = new DatagramPacket(this.buffer, this.buffer.length, this.packet.getAddress(), this.packet.getPort());
        this.client.receive(p);
        return new String(p.getData());
    }

    public static void main(String[] args) throws IOException
    {
        String serverHost = "127.0.0.1";
        int port = 10000;
        Client client = new Client(serverHost, port, "client说：服务器你好！".getBytes());
        client.send();
        //String info = client.receive(serverHost, port);
        System.out.println("客户端接收到:" + client.receive2());
    }

}