UDP代码示例

UDP 类似发短息 ，寄快递， 对方可收可不收

package JUC.UDP;

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

public class DatagramSocketTest {
    public static void main(String[] args) throws IOException {
        DatagramSocket datagramSocket = new DatagramSocket();
        String msg = "你好";
        //要发送的内容
        DatagramPacket datagramPacket = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length, InetAddress.getByName("localhost"),9999);
        datagramSocket.send(datagramPacket);//发送
        datagramSocket.close();
    }
}

package JUC.UDP;

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

public class DatagramServerTest {
    public static void main(String[] args) throws IOException {
        DatagramSocket datagramSocket = new DatagramSocket(9999);
        byte[] bytes = new byte[1024];
        DatagramPacket datagramPacket = new DatagramPacket(bytes, 0, bytes.length);
        System.out.println(new String(datagramPacket.getData(),0,datagramPacket.getLength()));
        datagramSocket.receive(datagramPacket);//接收
        datagramSocket.close();
    }
}

循环发送

package JUC.chat;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;

public class UdpSend {
    public static void main(String[] args) throws IOException {
        DatagramSocket datagramSocket = new DatagramSocket(9090);
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        while (true){
            String data = bufferedReader.readLine();
            DatagramPacket datagramPacket = new DatagramPacket(data.getBytes(),0,data.length(),new InetSocketAddress("localhost",6666));
            datagramSocket.send(datagramPacket);
            if (data.equals("bye")){
                break;
            }
        }
        datagramSocket.close();
    }
}

package JUC.chat;

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

public class UdpReceive {
    public static void main(String[] args) throws IOException {
        DatagramSocket datagramSocket = new DatagramSocket(6666);
        while (true){
            byte[] bytes = new byte[1024];
            DatagramPacket datagramPacket = new DatagramPacket(bytes, 0, bytes.length);
            datagramSocket.receive(datagramPacket);
            byte[] data = datagramPacket.getData();
            String s = new String(data, 0, data.length);
            System.out.println(s);
            if (s.equals("bye")){
                break;
            }
        }
        datagramSocket.close();
    }
}

多线程实现UDP方式聊天

package JUC.chat;

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

public class UdpSend implements Runnable{

    DatagramSocket datagramSocket = null;
    BufferedReader bufferedReader = null;
    private int toProt;
    private int prot;
    private String hostname;

    @Override
    public void run() {
        while (true){
            String data = null;
            try {
                data = bufferedReader.readLine();
                DatagramPacket datagramPacket = new DatagramPacket(data.getBytes(),0,data.length(),new InetSocketAddress(this.hostname,this.prot));
                datagramSocket.send(datagramPacket);
                if (data.equals("bye")){
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        datagramSocket.close();
    }

    public UdpSend(int toProt, int prot, String hostname) {
        this.toProt = toProt;
        this.prot = prot;
        this.hostname = hostname;
        try {
            datagramSocket = new DatagramSocket(this.toProt);
            bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        } catch (SocketException e) {
            e.printStackTrace();
        }
    }
}

package JUC.chat;

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

public class UdpReceive implements Runnable {

    DatagramSocket datagramSocket = null;
    private int prot;
    private String sayName;

    @Override
    public void run() {
        try {
            while (true){
                byte[] bytes = new byte[1024];
                DatagramPacket datagramPacket = new DatagramPacket(bytes, 0, bytes.length);
                datagramSocket.receive(datagramPacket);
                byte[] data = datagramPacket.getData();
                String s = new String(data, 0, data.length);
                System.out.println(this.sayName +":"+s);
                if (s.equals("bye")){
                    break;
                }
            }
            datagramSocket.close();
        }catch (Exception e) {
            e.printStackTrace();
        }
    }

    public UdpReceive(int prot, String sayName) {
        this.prot = prot;
        this.sayName = sayName;
        try {
            datagramSocket = new DatagramSocket(this.prot);
        } catch (SocketException e) {
            e.printStackTrace();
        }
    }
}

package JUC.chat;

public class TalkSendTest {
    public static void main(String[] args) {
        new Thread(new UdpSend(7777,9999,"localhost")).start();
        new Thread(new UdpReceive(8888,"tom")).start();
    }
}

public class TalkReceiveTest {
    public static void main(String[] args) {
        new Thread(new UdpSend(5555,8888,"localhost")).start();
        new Thread(new UdpReceive(9999,"honey")).start();
    }
}