Comment implémenter une fonction simple de téléchargement de fichiers à l'aide de MySQL et Java

CREATE TABLE files (
    id INT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(255) NOT NULL,
    type VARCHAR(100) NOT NULL,
    size INT NOT NULL,
    content LONGBLOB NOT NULL
);

<form action="upload" method="post" enctype="multipart/form-data">
    <input type="file" name="file" id="file">
    <input type="submit" value="上传">
</form>

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;
import org.apache.commons.io.IOUtils;

@WebServlet("/upload")
@MultipartConfig(maxFileSize = 1024 * 1024 * 10) // 限制文件大小为10MB
public class UploadServlet extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String fileName = "";
        String fileType = "";
        int fileSize = 0;
        InputStream fileContent = null;
        
        try {
            Part filePart = request.getPart("file");
            fileName = filePart.getSubmittedFileName();
            fileType = filePart.getContentType();
            fileSize = (int) filePart.getSize();
            fileContent = filePart.getInputStream();
            
            // 将文件内容保存到数据库
            saveFileToDatabase(fileName, fileType, fileSize, fileContent);
            
            response.getWriter().println("上传成功！");
        } catch (SQLException e) {
            response.getWriter().println("上传失败：" + e.getMessage());
        } finally {
            if (fileContent != null) {
                fileContent.close();
            }
        }
    }
    
    private void saveFileToDatabase(String fileName, String fileType, int fileSize, InputStream fileContent) throws SQLException {
        Connection conn = null;
        PreparedStatement stmt = null;
        
        try {
            conn = getConnection(); // 假设已实现获取数据库连接的方法getConnection()
            stmt = conn.prepareStatement("INSERT INTO files (name, type, size, content) VALUES (?, ?, ?, ?)");
            stmt.setString(1, fileName);
            stmt.setString(2, fileType);
            stmt.setInt(3, fileSize);
            stmt.setBinaryStream(4, fileContent);
            stmt.executeUpdate();
        } finally {
            if (stmt != null) {
                stmt.close();
            }
            if (conn != null) {
                conn.close();
            }
        }
    }

}