如何在java中从mysql数据库中检索blob图像

Question

是否正确？现在，当我尝试从数据库中检索blob数据时，它每次都会更改，为什么？那么如何检索此图像呢？以下是我尝试过的代码：

conn = new DB_Connection().makeConn();

                try {
                    stmnt = conn.createStatement();
                    String sql = "select * from student_info";
                    ResultSet rs = stmnt.executeQuery(sql);

                    // for save data
                    File file = new File("C:\\Users\\Hasibul Hasan Chowdh\\Desktop\\New folder\\adm.jpg");
                    FileInputStream fis = new FileInputStream(file);
                    PreparedStatement ps = conn.prepareStatement("insert into image_table (image) values(?)");
                    ps.setBinaryStream(1, fis, (int) file.length());
                    ps.executeUpdate();

                    System.out.println("Image inserted.");

                    if (rs.next()) {
                        // for retrieve data
                        byte[] img = rs.getBytes("image");
                        //InputStream binaryStream = rs.getBinaryStream("image");
                        ImageIcon imgIcon = new ImageIcon(img);
                        Image image = imgIcon.getImage();
                        Image img2 = image.getScaledInstance(lblNewLabel.getWidth(), lblNewLabel.getHeight(),
                                Image.SCALE_SMOOTH);
                        ImageIcon imgIcn = new ImageIcon(img2);
                        lblNewLabel.setIcon(imgIcn);
                        System.out.println("SOmeyhing");

                    } else {
                        JOptionPane.showMessageDialog(null, "Image not found.", "Error!", JOptionPane.OK_OPTION);
                    }

                    stmnt.close();
                    conn.close();

                } catch (SQLException | FileNotFoundException ex) {
                    ex.printStackTrace();
                }

我没有看到任何图像。为什么？请帮忙。谢谢

Answer 1

使用此语句获取表中最后插入的行：

SELECT fields FROM student_info ORDER BY id DESC LIMIT 1;