CODEWITHSUNDEEP
javahtmljsp
TheHost
TheHost

Reputation: 45

out.println in JSP

I wrote this jsp code. It is a basic login control. I am trying to check inputs with my database. If they are correct then there is no problem but if the inputs are null or they are not in database I want to give error and redirect the guest to the login page.

<%@ page import ="java.sql.*" %>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Login Process</title>
</head>
<body>
<%
    String userid = request.getParameter("username");    
    String pwd = request.getParameter("password");
    Class.forName("com.mysql.jdbc.Driver");

    Connection con = DriverManager.getConnection("jdbc:mysql://localhost/ecommerce", "root1" , "1234");
    Statement st = con.createStatement();
    ResultSet rs;
    rs = st.executeQuery("select * from users where UserFirstName='" + userid + "' and UserPassword='" + pwd + "'");
    while(rs.next()){
        if(userid.length()!= 0 || pwd.length()!= 0){
            if (rs.getInt("Admin") == 1) {
                session.setAttribute("userid", userid);
                response.sendRedirect("Admin.jsp");
            } else if(rs.getInt("Admin") == 0){
                session.setAttribute("userid", userid);
                response.sendRedirect("User.jsp");
            }
            else {
                out.println("Invalid username or password <a href='index.jsp'>try again</a>");
            }
        }
        else{
            out.println("Empty username or password <a href='index.jsp'>try again</a>");
        }
    }
%>
</body>

In this code two line is not working

else {
           out.println("Invalid username or password <a href='index.jsp'>try again</a>");
            }

and this one

else{
            out.println("Empty username or password <a href='index.jsp'>try again</a>");
        }

my browser just gives me a blank page instead else scopes.

Upvotes: 0

Views: 5528

Answers (2)

Nidheesh
Nidheesh

Reputation: 672

Enclose the code in try - catch block and if any exception occurred will redirect to login page. 

try
{
String userid = request.getParameter("username");    
String pwd = request.getParameter("password");
Class.forName("com.mysql.jdbc.Driver");

Connection con = DriverManager.getConnection("jdbc:mysql://localhost/ecommerce", "root1" , "1234");
Statement st = con.createStatement();
ResultSet rs;
rs = st.executeQuery("select * from users where UserFirstName='" + userid + "' and UserPassword='" + pwd + "'");

while(rs.next())
{
    if(userid.length()!= 0 || pwd.length()!= 0){
    if (rs.getInt("Admin") == 1) {
            session.setAttribute("userid", userid);
            response.sendRedirect("Admin.jsp");
      } else if(rs.getInt("Admin") == 0){
            session.setAttribute("userid", userid);
            response.sendRedirect("User.jsp");
        }
        else {
            out.println("Invalid username or password <a href='index.jsp'>try again</a>");
        }
    }
    else{
        out.println("Empty username or password <a href='index.jsp'>try again</a>");
    }
}
}
  catch (Exception e)
    {
          out.println("Exception: "+e.getMessage()+" :Invalid username or password <a href='index.jsp'>try again</a>");
      }

e.getMessage(), will show the exception message, is optional since it will help for debugging but may reveal sensitive information if it is in a production system.

Upvotes: 0

Braj
Braj

Reputation: 46881

if the inputs are null or they are not in database I want to give error

use if (rs.next()) instead of while (rs.next()) to check for no records.

Sample code: (Modify it as per your requirement)

String userid = request.getParameter("username");
String pwd = request.getParameter("password");

// check for empty username or password before making a call to database
if (userid == null || userid.trim().length() == 0 || pwd == null
        || pwd.trim().length() == 0) {
   out.println("Invalid username or password <a href='index.jsp'>try again</a>");
} else {
   ... // request for database query
   if (rs.next()) { // use if instead of while to check for no record
   ...
   } else {
     out.println("Empty username or password <a href='index.jsp'>try again</a>");
   }
}

Upvotes: 1

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