使用Java实现在同一个wifi下两台电脑双向一来一回的传输文件

实现在同一个wifi下两台电脑双向一来一回的传输文件，可以考虑使用Socket编程。以下是一个简单的Java程序示例：

1. 服务端代码

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

public class FileServer {
    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = new ServerSocket(9999);
        System.out.println("Server started.");

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

            InputStream in = socket.getInputStream();
            OutputStream out = socket.getOutputStream();

            byte[] buffer = new byte[1024];
            int len;

            // 读取客户端发送的文件名
            len = in.read(buffer);
            String fileName = new String(buffer, 0, len);

            // 发送服务器上的文件到客户端
            File file = new File(fileName);
            FileInputStream fileIn = new FileInputStream(file);
            while ((len = fileIn.read(buffer)) > 0) {
                out.write(buffer, 0, len);
            }
            fileIn.close();

            socket.close();
        }
    }
}

2. 客户端代码

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

public class FileClient {
    public static void main(String[] args) throws IOException {
        Socket socket = new Socket("192.168.0.100", 9999);
        System.out.println("Connected to server.");

        InputStream in = socket.getInputStream();
        OutputStream out = socket.getOutputStream();

        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        System.out.print("Enter file name: ");
        String fileName = reader.readLine();

        // 发送文件名到服务器
        out.write(fileName.getBytes());

        // 从服务器接收文件并保存到本地
        byte[] buffer = new byte[1024];
        int len;
        FileOutputStream fileOut = new FileOutputStream("received_" + fileName);
        while ((len = in.read(buffer)) > 0) {
            fileOut.write(buffer, 0, len);
        }
        fileOut.close();

        socket.close();
    }
}

注意：在运行代码前需要先确定两台电脑在同一个wifi下，且需要替换上述代码中的IP地址为服务端所在电脑的IP地址。