JAVA EE初阶 6：网络编程套接字

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

java 复制代码

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

java 复制代码

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();
    }   

}