java将来自数据库的文件下载到PC

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class FileDownloader {
    public static void main(String[] args) {
        String jdbcUrl = "jdbc:mysql://localhost:3306/mydatabase";
        String username = "username";
        String password = "password";
        String fileId = "123"; // 文件在数据库中的唯一标识

        try (Connection connection = DriverManager.getConnection(jdbcUrl, username, password)) {
            String sql = "SELECT file_data FROM files WHERE id = ?";
            try (PreparedStatement statement = connection.prepareStatement(sql)) {
                statement.setString(1, fileId);
                try (ResultSet resultSet = statement.executeQuery()) {
                    if (resultSet.next()) {
                        InputStream fileData = resultSet.getBinaryStream("file_data");
                        saveFileToPC(fileData, "downloaded_file.txt");
                        System.out.println("文件下载成功！");
                    } else {
                        System.out.println("未找到文件！");
                    }
                }
            }
        } catch (SQLException | IOException e) {
            e.printStackTrace();
        }
    }

    private static void saveFileToPC(InputStream fileData, String filePath) throws IOException {
        try (OutputStream outputStream = new FileOutputStream(filePath)) {
            byte[] buffer = new byte[4096];
            int bytesRead;
            while ((bytesRead = fileData.read(buffer)) != -1) {
                outputStream.write(buffer, 0, bytesRead);
            }
        }
    }
}