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JAVA EE初阶 6：网络编程套接字

news 2025/11/16 7:52:02

本节目标：

1.网络编程基础

2.Socket套接字

3.UDP数据报套接字编程

4.TCP流套接字编程

1.网络编程基础

1.1 原因

1.2 网络编程中的基本概念

2.Socket套接字

3.UDP数据报套接字编程

3.1 API介绍

3.2 代码示例

UDP Echo Server

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;public class EchoServer {//创建 socket 对象private DatagramSocket socket;//构造方法public EchoServer(int port) throws SocketException  {socket = new DatagramSocket(port);}//启动服务器，完成主要业务逻辑public void start() throws IOException{System.out.println("服务器启动！");while (true) {//1 从客户端读取请求并解析//(1) 创建一个空白的 DatagramPacket 对象DatagramPacket reqPacket = new DatagramPacket(new byte[4096], 4096);//(2) 通过 receive 读取网卡数据，如果网卡没有收到数据，就会阻塞等待。socket.receive(reqPacket);//(3) 把 DatagramPacket 中的数据转换为字符串，只需要从 DatagramPacket 中读取有效数据即可。String request = new String(reqPacket.getData(), 0, reqPacket.getLength());//2 根据请求计算响应String response = process(request);//3 把响应写回客户端//(1) 把响应构成 DatagramPacket 对象DatagramPacket respPacket = new DatagramPacket(response.getBytes(), response.getBytes().length,reqPacket.getSocketAddress());//(2) 把 DatagramPacket 写回给客户端socket.send(respPacket);//4 打印日志System.out.printf("[%s:%d] req: %s, resp: %s\n",reqPacket.getAddress(),reqPacket.getPort(),request,response);}}//由于我们是 "回显服务器" ,所以响应和请求是一样的，这里直接返回请求即可。 private String process(String request) {return request;}public static void main(String[] args) throws IOException {EchoServer server = new EchoServer(65535);server.start();}}

UDP Echo Client

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.util.Scanner;public class EchoClient {private DatagramSocket socket = null;private String severIp;private int serverPort;public EchoClient(String severIp,int serverPort) throws SocketException {this.severIp = severIp;this.serverPort = serverPort;socket = new DatagramSocket();}public void start() throws IOException {Scanner Scanner = new Scanner(System.in);System.out.println("客户端启动！");while (true) {//1.从控制台读取数据System.out.println("请输入：");String request = Scanner.next();//2.构造UDP请求 把数据封装成 DatagramPa 不光要填内容，还要填服务器的地址和端口DatagramPacket reqPacket = new DatagramPacket(request.getBytes(), request.getBytes().length,InetAddress.getByName(severIp), serverPort);socket.send(reqPacket);//3.接收服务器的响应DatagramPacket respPacket = new DatagramPacket(new byte[4096], 4096);socket.receive(respPacket);String response = new String(respPacket.getData(), 0, respPacket.getLength());//4.把响应显示到控制台System.out.println("服务器响应：" + response);}}public static void main(String[] args) throws SocketException, IOException {EchoClient echoClient = new EchoClient("127.0.0.1", 9090);echoClient.start();}   }