使用java类，servlet，jsp以及会话和数据库进行简单的登录身份验证

Question

I want to make a login process using mvc structure where i send userid and password from index.jsp page.If they match with the database value then it will go to the stater001.jsp .In index.jsp i've 2 fields userid and password from.I've post userid and pwd into LoginServlet servlet.

LoginServlet process userid , pwd making the instance of loginAuthentication class. loginAuthentication class checks whether userid and password exists in database or not with select query .I have also used setter getter class user to set userid and pwd into session.I tried to do the whole login process in an organised way.But i'm stucked with error i couldn't under stand what is the problem please help me to solve this.First i tried it without using mvc pattern then it worked fine.But now it is not working. Below is my previous code all process in one servlet

package DataAccess;
import DataAccess.dbconnector;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
  import java.io.*;
 import javax.servlet.*;
import javax.servlet.http.*;
 import java.sql.*;
import java.util.logging.Level;
import java.util.logging.Logger;

@WebServlet(urlPatterns = {"/LoginServlet"})
public class LoginServlet extends HttpServlet {

String userid, pwd;
  Connection connection = null;
protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    response.setContentType("text/html;charset=UTF-8");
    PrintWriter out = response.getWriter();

    Statement statement = null;
   userid = request.getParameter("uname");
    pwd = request.getParameter("pass");
    try {
        dbconnector dbc = new dbconnector();
        connection = dbc.Open();
        PreparedStatement ps = connection.prepareStatement("select * from member where uname='" + userid + "' and pass='" + pwd + "'");

        ResultSet rs = ps.executeQuery();
        if (rs.next()) {
            HttpSession session = request.getSession();
            session.setAttribute("userid", userid);
            response.sendRedirect("view/starter001.jsp");
        } else {

            request.setAttribute("errorMessage", "Invalid user or password");
            RequestDispatcher rd = getServletContext().getRequestDispatcher("/index.jsp");
            rd.include(request, response);

        }

    } catch (Exception e) {
        e.printStackTrace();
    }
 finally {
        try {
            connection.close();
        } catch (SQLException ex) {
            Logger.getLogger(LoginServlet.class.getName()).log(Level.SEVERE, null, ex);
        }
    }


}

}

And in my new code here i've stucked with error in execution And here i've attached my new edited codes where i tried to do this in an organised way .My errors have been gone but not showing the userid after login http://pastebin.com/RKyieMqn Please consider my question

at first when all codes were in loginservlet then it was like but when i start using mvc structure it is not showing the username

Answer 1

Obviously, you pasted the wrong code: In the below statement, where is the variable user defined? session.setAttribute("user", user);

Perhaps, you have created a authenticateUser object somewhere. Please check you code to find it.

Answer 2

I have changed session.setAttribute("userid", user); to session.setAttribute("userid", user.getUserId()); and now it's working