UDP 类似于发短信，不用连接，只需要知道接收端的地址发送消息发送端package com.network.lesson03; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; /** * @Author suaxi * @Date 2020/11/23 11:03 * UDP发送消息，不需要连接服务器 */ public class UpdClientDemo01 { public static void main(String[] args) throws Exception { //1、建立一个socket DatagramSocket datagramSocket = new DatagramSocket(); //2、建立包 String mgs = "故乡的樱花开了！"; InetAddress localhost = InetAddress.getByName("localhost"); int port = 8888; //数据 数据的长度起始 要发送给谁 DatagramPacket datagramPacket = new DatagramPacket(mgs.getBytes(), 0, mgs.length(),localhost,port); //3、发送包 datagramSocket.send(datagramPacket); //4、关闭流 datagramSocket.close(); } } 接收端package com.network.lesson03; import java.net.DatagramPacket; import java.net.DatagramSocket; /** * @Author suaxi * @Date 2020/11/23 11:18 * UDP接收端，还是要等待客户端的连接 */ public class UpdServerDemo01 { public static void main(String[] args) throws Exception { //开放端口 DatagramSocket datagramSocket = new DatagramSocket(8888); //接收数据包 byte[] bytes = new byte[1024]; DatagramPacket datagramPacket = new DatagramPacket(bytes, 0, bytes.length); datagramSocket.receive(datagramPacket); //阻塞接收 System.out.println(datagramPacket.getAddress().getHostAddress()); //接收地址 System.out.println(new String(datagramPacket.getData(),0,datagramPacket.getLength())); //数据包消息 //关闭连接 datagramSocket.close(); } } 循环发送消息package com.network.chat; import java.io.BufferedReader; import java.io.InputStreamReader; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; import java.net.InetSocketAddress; /** * @Author suaxi * @Date 2020/11/23 11:34 * 发送消息 */ public class UdpSenderDemo01 { public static void main(String[] args) throws Exception { DatagramSocket datagramSocket = new DatagramSocket(8888); //准备数据，控制台读取输入的数据System.in BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in)); while (true){ String data = bufferedReader.readLine(); byte[] bytes = data.getBytes(); DatagramPacket packet = new DatagramPacket(bytes, 0, bytes.length, new InetSocketAddress("localhost", 8889)); datagramSocket.send(packet); if (data.equals("bye")){ break; } } datagramSocket.close(); } } package com.network.chat; import java.net.DatagramPacket; import java.net.DatagramSocket; /** * @Author suaxi * @Date 2020/11/23 11:34 * UDP聊天咨询Demo（循环接收） */ public class UdpReciverDemo01 { public static void main(String[] args) throws Exception { DatagramSocket datagramSocket = new DatagramSocket(8889); while (true){ //准备接收包裹 byte[] bytes = new byte[1024]; DatagramPacket datagramPacket = new DatagramPacket(bytes, 0, bytes.length); datagramSocket.receive(datagramPacket); //阻塞式接收包裹 byte[] data = datagramPacket.getData(); String reciveData = new String(data, 0, data.length); System.out.println(reciveData); //断开连接 if (reciveData.equals("bye")){ break; } } datagramSocket.close(); } } 在线咨询，两者都是发送方，也都可以是接收方发送端package com.network.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; /** * @Author suaxi * @Date 2020/11/23 14:37 */ public class TalkSend implements Runnable{ DatagramSocket datagramSocket = null; BufferedReader bufferedReader = null; private int fromPort; private String toIP; private int toPort; public TalkSend(int fromPort, String toIP, int toPort) { this.fromPort = fromPort; this.toIP = toIP; this.toPort = toPort; try { datagramSocket = new DatagramSocket(fromPort); bufferedReader = new BufferedReader(new InputStreamReader(System.in)); } catch (SocketException e) { e.printStackTrace(); } } @Override public void run() { while (true){ try { String data = bufferedReader.readLine(); byte[] bytes = data.getBytes(); DatagramPacket packet = new DatagramPacket(bytes, 0, bytes.length, new InetSocketAddress(this.toIP, this.toPort)); datagramSocket.send(packet); if (data.equals("bye")){ break; } } catch (IOException e) { e.printStackTrace(); } } datagramSocket.close(); } } 接收端package com.network.chat; import java.io.IOException; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.SocketException; /** * @Author suaxi * @Date 2020/11/23 14:43 */ public class TalkRecive implements Runnable{ DatagramSocket datagramSocket = null; private int port; private String mgsFrom; public TalkRecive(int port,String mgsFrom) { this.port = port; this.mgsFrom = mgsFrom; try { datagramSocket = new DatagramSocket(port); } catch (SocketException e) { e.printStackTrace(); } } @Override public void run() { while (true){ try { //准备接收包裹 byte[] bytes = new byte[1024]; DatagramPacket datagramPacket = new DatagramPacket(bytes, 0, bytes.length); datagramSocket.receive(datagramPacket); //阻塞式接收包裹 byte[] data = datagramPacket.getData(); String reciveData = new String(data, 0, data.length); System.out.println(mgsFrom+":"+reciveData); //断开连接 if (reciveData.equals("bye")){ break; } } catch (IOException e) { e.printStackTrace(); } } datagramSocket.close(); } } 具体实现：package com.network.chat; /** * @Author suaxi * @Date 2020/11/23 14:46 */ public class TalkStudent { public static void main(String[] args) { //开启两个线程 new Thread(new TalkSend(7777,"localhost",8888)).start(); new Thread(new TalkRecive(9999,"老师")).start(); } } package com.network.chat; /** * @Author suaxi * @Date 2020/11/23 14:48 */ public class TalkTeacher { public static void main(String[] args) { new Thread(new TalkSend(7778,"localhost",9999)).start(); new Thread(new TalkRecive(8888,"学生")).start(); } }