Geek Answers Handbook

Create a sample login page using servlet and JSP?

I designed a sample login page to verify the username and password. If the user gives the correct credentials, the page will move on some other page, otherwise return the message from servlet to the same login page.

Here I have attached sample code :

FirstJSP.jsp

 <%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>` <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org /TR/html4/loose.dtd">` <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Insert title here</title>` </head> <body> <form action="Login" method="post"> <input type="text" name="Name"/><br> <input type="password" name=Pass><br><br><br> <input type="submit" value="submit"/><br> <%if(request.getAttribute("message")!=("")) out.println(request.getAttribute("message")); else out.println("");%> <h1>Hi This is JSP sample code </h1> <font color="blue" size="25"> <marquee>Please login to Work with JSP</marquee></font> <%java.text.DateFormat df = new java.text.SimpleDateFormat("MM/dd/yyyy"); %> <h1>Current Date: <%= df.format(new java.util.Date()) %> </h1> </form> </body> </html>

And servlet code, Login.java:

 package com.controller; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class Login extends HttpServlet { private static final long serialVersionUID = 1L; public Login() { super(); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String username = request.getParameter("Name"); String password = request.getParameter("Pass"); response.setContentType("text/html"); if(username.equals("sugan") && password.equals("raj")) { response.getWriter().println("<html><body><Marquee>Welcome to JSP!!!</marquee></body></html>"); } else { String message = "OOps!!! Invalid Username/Password"; request.setAttribute("message", message); request.getRequestDispatcher("/FirstJSP.jsp").forward(request, response); } } }

It works fine, but when loading the login page, it automatically displays Null . Then, if the user gives the wrong credentials, he displays the actual message. How to disable Null message at runtime?

+4
source share
3 answers

You are comparing a message to an empty string using == .

Firstly, your comparison is incorrect, because the message will be null (and not an empty string).

Secondly, this is wrong, because objects need to be compared with equals() , not with == .

Thirdly, this is wrong because you should avoid scripting in JSP and use JSP EL, JSTL, and other custom tags instead:

 <c:id test="${!empty message}"> <c:out value="${message}"/> </c:if>
+4
source

You really don't use the doGet () method. When you open the page, it issues a GET request, not a POST.

Try replacing doPost () with service () instead ... then you use the same method to handle GET and POST requests.

...

0
source

As I can see, you are comparing a message with an empty string using ==.

Its very difficult to write the complete code, but I can say that the code stream is to create the class and db method first, and then return the connection. secondly, create a feed (ex -login.java) and import this db class into this servlet. thirdly, create an instance of the imported db class using the new operator and call the connection method of this db class. fourth, creaet prepared the statement and the execution statement and put this code in a catch catch block to handle exceptions. Use the if-else clause in the try block to navigate your login page based on success or failure.

Hope this helps you. If there is any problem, please return.

Nikil Pahariya

0
source

More articles:


All Articles