使用Java实现在局域网内通讯

要在局域网内实现通讯，可以使用Java的Socket编程。以下是一个简单的示例：

1. 服务端代码

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

public class Server {
    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = new ServerSocket(12345);
        System.out.println("Server started");

        while (true) {
            Socket clientSocket = serverSocket.accept();
            System.out.println("New client connected: " + clientSocket);

            BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
            PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);

            String inputLine;
            while ((inputLine = in.readLine()) != null) {
                System.out.println("Received message from client: " + inputLine);
                out.println("Server received your message: " + inputLine);
            }

            System.out.println("Client disconnected");
            in.close();
            out.close();
            clientSocket.close();
        }
    }
}

2. 客户端代码

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

public class Client {
    public static void main(String[] args) throws IOException {
        Socket socket = new Socket("localhost", 12345);
        System.out.println("Connected to server");

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

        BufferedReader userInput = new BufferedReader(new InputStreamReader(System.in));
        String inputLine;

        while ((inputLine = userInput.readLine()) != null) {
            out.println(inputLine);

            String response = in.readLine();
            System.out.println("Received response from server: " + response);
        }

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

在这个示例中，服务端在12345端口上监听客户端连接。当有新的客户端连接时，服务端会创建一个新的线程来处理该客户端的请求。客户端连接到localhost上的12345端口，发送数据给服务端，然后等待服务端的响应。当客户端输入exit时，它会关闭连接并退出。