java实现开发TCP客户端与服务端，客户端从键盘输入一个四则运算表达式（如“1+2”、“6/3”等）并发送给服务端。服务端接收后执行运行，并将结果返回给客户端

以下是Java实现开发TCP客户端与服务端，客户端从键盘输入一个四则运算表达式并发送给服务端，服务端接收后执行运行，并将结果返回给客户端的代码：

服务端代码：

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

public class TCPServer {
    public static void main(String[] args) throws Exception {
        ServerSocket serverSocket = new ServerSocket(8888);
        System.out.println("Server started.");

        while (true) {
            Socket socket = serverSocket.accept();
            System.out.println("Client " + socket.getInetAddress() + " connected.");

            new Thread(() -> {
                try {
                    BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                    PrintWriter writer = new PrintWriter(socket.getOutputStream(), true);

                    String expression;
                    while ((expression = reader.readLine()) != null) {
                        System.out.println("Received expression: " + expression);

                        // 计算表达式
                        int result = Calculator.calculate(expression);

                        // 发送结果
                        writer.println(result);
                        System.out.println("Sent result: " + result);
                    }

                    reader.close();
                    writer.close();
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }).start();
        }
    }
}

class Calculator {
    public static int calculate(String expression) {
        String[] tokens = expression.split(" ");
        int a = Integer.parseInt(tokens[0]);
        int b = Integer.parseInt(tokens[2]);
        switch (tokens[1]) {
            case "+":
                return a + b;
            case "-":
                return a - b;
            case "*":
                return a * b;
            case "/":
                return a / b;
            default:
                throw new IllegalArgumentException("Invalid operator: " + tokens[1]);
        }
    }
}

客户端代码：

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

public class TCPClient {
    public static void main(String[] args) throws Exception {
        Socket socket = new Socket("localhost", 8888);
        System.out.println("Connected to server.");

        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        PrintWriter out = new PrintWriter(socket.getOutputStream(), true);

        String expression;
        while ((expression = reader.readLine()) != null) {
            // 发送表达式
            out.println(expression);

            // 接收结果
            String result = in.readLine();
            System.out.println("Result: " + result);
        }

        reader.close();
        in.close();
        out.close();
        socket.close();
    }
}