Java网络编程—UDP实现两个用户互相发送消息

UDP不需要实现两个用户连接就可以发送消息，所以直接开两个线程，一个发送，一个接受就可以实现。

Sever端程序: 一，调用DatagramSocket(int port)创建一个数据报套接字，绑定在指定端口上； 二，调用DatagramPacket(byte[] buf,int length),建立一个字节数组来接收UDP包； 三，调用DatagramSocket.receive()； 四，最后关闭数据报套接字。

Client端程序: 一，调用DatagramSocket()创建一个数据报套接字； 二，调用DatagramPacket(byte[] buf,int offset,InetAddress address,int port),建立要发送的UDP包 三，调用DatagramSocket类的send方法发送数据包； 四，关闭数据报套接字。

数据报套接字发送成功后，相当于建立了一个虚连接，双方可以发送数据。

接收端：

代码语言：javascript复制

package net.udp;

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

public class Receiver implements Runnable {
    private int port;
    private DatagramSocket datagramSocket;

    public Receiver(int port) throws SocketException {
        this.port = port;
        datagramSocket = new DatagramSocket(port);
    }

    @Override
    public void run() {
        while (true) {
            try {
                byte[] buf = new byte[1024];
                DatagramPacket datagramPacket = new DatagramPacket(buf, buf.length);
                datagramSocket.receive(datagramPacket);
                byte[] data = datagramPacket.getData();
                String strdata = new String(data, 0, data.length);
                System.out.println(strdata);
            } catch (SocketException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

发送端：

代码语言：javascript复制

package net.udp;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;

public class Send implements Runnable {
    BufferedReader reader = null;
    private String adress;
    private int port;
    private DatagramSocket datagramSocket;

    public Send(String adress, int port) throws SocketException {
        this.adress = adress;
        this.port = port;
        datagramSocket = new DatagramSocket();
        InputStream in;
        reader = new BufferedReader(new InputStreamReader(System.in));
    }

    @Override
    public void run() {

        while (true) {
            try {
                byte[] buf = reader.readLine().getBytes();
                DatagramPacket datagramPacket = new DatagramPacket(buf, buf.length, InetAddress.getByName(adress), port);
                datagramSocket.send(datagramPacket);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}

用户一

代码语言：javascript复制

package net.udp;

import java.net.SocketException;

public class Test_1 {
    public static void main(String[] args) throws SocketException {
        Send send = new Send("127.0.0.1", 6666);
        Receiver receiver = new Receiver(8080);
        new Thread(send).start();
        new Thread(receiver).start();
    }
}

用户二

代码语言：javascript复制

package net.udp;

import java.net.SocketException;

public class Test_2 {
    public static void main(String[] args) throws SocketException {
        Send send = new Send("127.0.0.1", 8080);
        Receiver receiver = new Receiver(6666);
        new Thread(send).start();
        new Thread(receiver).start();
    }
}

udp socket编程

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