File file = new File("image/temp.jpg");
            if(file.exists()){
           file.delete();
           file.createNewFile();
        }else{
            file.createNewFile();
        }
             InputStream in = rs.getBinaryStream(5); //rs是连接数据库返回的ResultSet对象
            FileOutputStream out = new FileOutputStream("image/temp.jpg");
            byte[] bytes = new byte[1024];
            int n;//将读取的文件写入到out流中
            while ((n = in.read(bytes)) != -1) {
                out.write(bytes, 0, n);
            }
            in.close();
            out.close();
            ImageIcon icon = new ImageIcon("image/temp.jpg");
            
            JFrame frame = new JFrame(); JPanel panel = new JPanel();
            frame.getContentPane().add(panel);
            frame.getContentPane().setLayout(null); panel.setSize(400,400);
            frame.setSize(400,400); panel.add(new JLabel(icon));
            frame.setVisible(true);