TCP服务器（以Echo服务器为例））

原創

渴望成功！

2020-07-08 00:37

TCP服务器

他也涉及到两个核心的类
ServerSocket
Socket

这里注意：
UDP协议无连接，类似发微信，直接发就行
TCP协议有连接，类似打电话，要接通才能通话。

这里依然用回显服务器模式来体会TCP服务器：

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;

public class TcpEchoServer {
    private ServerSocket serverSocket = null;

    public TcpEchoServer(int port) throws IOException {
        serverSocket = new ServerSocket(port);
    }
    public void start() throws IOException {
        System.out.println("服务器启动");
        //进入主循环
        while (true) {
           //获取内核连接
            Socket clientSocket = serverSocket.accept();
            //处理连接
            processConnection(clientSocket);
        }
    }

    private void processConnection(Socket clientSocket) {
        System.out.printf("[%s:%d] 客户端上线\n",clientSocket.getInetAddress().toString(),
                clientSocket.getPort());
        //获取clientSocket中的流对象
        try(BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
            BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(clientSocket.getOutputStream()))) {
            //客户端和服务器有时并不是只交互一次
            //这时服务器处理的方式
            //（短连接）1.一个连接客户端和服务器只交互一次完毕之后就断开连接
            //（长连接）2.一个连接中客户端和服务器交互N次，直到满足一定条件再断开连接
            //当客户端断开连接，循环就结束啦
            //当断开连接，readLine或者write就会触发异常
            //此处为长连接
            while (true) {
                //客户端发送的数据必须按行
                String request = bufferedReader.readLine();
                String response = process(request);
                bufferedWriter.write(response+"\n");
                System.out.printf("[%s:%d] req: %s;resp %s\n",clientSocket.getInetAddress().toString(),
                        clientSocket.getPort(),request,response);
            }
        } catch (IOException e) {
            System.out.printf("[%s:%d] 客户端下线\n",clientSocket.getInetAddress().toString(),
                    clientSocket.getPort());
        }
    }

    private String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        TcpEchoServer server = new TcpEchoServer(9090);
        server.start();
    }
}

import java.io.*;
import java.net.Socket;
import java.util.Scanner;

public class TcpEchoClient {
    //a.启动客户端(和服务器建立连接）
    //b.进入主循环
    //1.读取用户输入内容
    //2.构造请求发送给服务器
    //3.读取响应
    //4.吧响应显示在界面
    private Socket socket = null;

    public TcpEchoClient(String serverIp,int serverPort) throws IOException {
        socket = new Socket(serverIp,serverPort);
    }
    public void start() {
        System.out.println("客户端启动");
        Scanner scanner = new Scanner(System.in);
        try(BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()))) {
            while (true) {
                System.out.print("->");
                String request = scanner.nextLine();
                if (request.equals("exit")) {
                    break;
                }
                //构造请求并发送
                bufferedWriter.write(request+"\n");
                //读取响应
                //请求和响应格式不一定相同
                String response = bufferedReader.readLine();
                System.out.println(response);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}