java使用Socket实现TCP协议的excel文件从服务器上传和下载到本机的开发实现

在Java中，使用Socket来实现TCP协议的Excel文件上传和下载可以分为几个步骤：

**1. 创建Server端（接收文件）：**

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

public class FileTransferServer {
    private ServerSocket serverSocket;

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

    public void start() throws IOException {
        serverSocket = new ServerSocket(8000); // 设置监听端口
        System.out.println("Server started on port 8000");

        while (true) {
            Socket clientSocket = serverSocket.accept(); // 等待客户端连接
            handleClientConnection(clientSocket);
        }
    }

    private void handleClientConnection(Socket socket) {
        try (BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
             PrintWriter out = new PrintWriter(socket.getOutputStream(), true)) {

            String command = in.readLine();
            if ("upload".equals(command)) { // 接收命令，判断是上传还是下载
                // 读取文件并发送到客户端
                File fileToUpload = ...; // 获取要上传的文件
                FileInputStream fis = new FileInputStream(fileToUpload);
                byte[] data = new byte[(int) fileToUpload.length()];
                fis.read(data);
                out.println("File sent");
                out.write(data);
            } else if ("download".equals(command)) {
                // 从本地目录读取文件，并发送给客户端
                File fileToLocalDownload = ...; // 获取要下载的文件路径
                FileChannel channel = new FileInputStream(fileToLocalDownload).getChannel();
                out.println("Preparing to send file");
                out.write(channel.map(FileChannel.MapMode.READ_ONLY, 0, fileToLocalDownload.length()));
                channel.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            clientSocket.close();
        }
    }
}

**2. 创建Client端（上传/下载文件）：**

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

public class FileTransferClient {
    public static void main(String[] args) {
        FileTransferClient client = new FileTransferClient("localhost", 8000);
        client.sendFileOrRequestFile("upload"); // 调用对应的方法进行上传
        // 或者
        client.sendFileOrRequestFile("download"); // 下载文件
    }

    private void sendFileOrRequestFile(String action) {
        try (Socket socket = new Socket("localhost", 8000);
             PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
             BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()))) {

            out.println(action);
            String response = in.readLine();
            if ("File sent".equals(response)) { // 上传响应
                // 读取响应数据并保存到本地
                File file = ...; // 定义保存路径
                FileOutputStream fos = new FileOutputStream(file);
                fos.write(<file_data>);
                fos.close();
            } else if ("Preparing to send file".equals(response)) { // 下载响应
                // 读取整个文件
                File file = ...; // 定义临时文件保存位置
                FileChannel channel = new FileOutputStream(file).getChannel();
                channel.transferFrom(socket.getChannel(), 0, file.length());
                channel.close();
            }

        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

在这个例子中，`<file_data>`应替换为实际接收到的数据。