@@@关于图象存取的问题@@@ 急！！！

import java.sql.*;
import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;public class DownLoad extends HttpServlet{
    public DownLoad() {
    }
    public void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
        doPost(request,response);
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
        System.out.println("======DownLoad begin=====");
        try{
            Class.forName("oracle.jdbc.driver.OracleDriver");
            Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:aptech","scott","tiger");
            Statement stmt=conn.createStatement();
            int id=Integer.parseInt(request.getParameter("id"));
            String sql="SELECT imageid, data FROM images where imageid="+id;
            ResultSet rs=stmt.executeQuery(sql);
            if(rs.next()){
                Blob blob = rs.getBlob("data");
                byte[] ab = blob.getBytes(1, (int)blob.length());
                response.setContentType("image/gif");
                response.reset();
                ServletOutputStream op = response.getOutputStream();
                op.write(ab);
                op.flush();
                op.close();
            }
        }catch(Exception ex){
            ex.printStackTrace();
        }
        System.out.println("======DownLoad end=====");
    }
}