jsp下载数据库图片

<%@ page import="java.sql.*" %>
<%@ page import="java.io.*" %>

<%
    // 数据库连接信息
    String url = "jdbc:mysql://localhost:3306/mydatabase";
    String username = "root";
    String password = "password";

    // 图片ID（从请求参数中获取）
    String imageId = request.getParameter("id");

    // 加载数据库驱动
    Class.forName("com.mysql.jdbc.Driver");

    // 建立数据库连接
    Connection conn = DriverManager.getConnection(url, username, password);

    // 执行SQL查询
    String sql = "SELECT image_data FROM images WHERE id = ?";
    PreparedStatement pstmt = conn.prepareStatement(sql);
    pstmt.setString(1, imageId);
    ResultSet rs = pstmt.executeQuery();

    // 检查是否找到图片数据
    if (rs.next()) {
        // 获取图片数据
        Blob imageData = rs.getBlob("image_data");
        InputStream inputStream = imageData.getBinaryStream();

        // 设置响应头
        response.setContentType("image/jpeg"); // 根据实际情况设置图片类型
        response.setContentLength((int) imageData.length());
        response.setHeader("Content-Disposition", "attachment; filename=image.jpg");

        // 将图片数据写入响应输出流
        OutputStream outputStream = response.getOutputStream();
        byte[] buffer = new byte[4096];
        int bytesRead;
        while ((bytesRead = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, bytesRead);
        }

        // 关闭流
        inputStream.close();
        outputStream.close();
    } else {
        response.getWriter().println("图片未找到");
    }

    // 关闭数据库连接
    rs.close();
    pstmt.close();
    conn.close();
%>