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is this good for logout page

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posted 14 years ago

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in my project i set many session varibles.
i write a log out jsp page and include it many pages.
here is my logout.jsp

<%-- 
    Document   : logout
    Created on : Apr 25, 2010, 8:44:05 AM
    Author     : aruna
--%>

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!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=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <div align="right">
            <form>
                <input type="button" name="logout" value="logout">
            </form>
        </div>
        <%
            if (session.getAttribute("username") != null) {
                session.removeAttribute("username");
            } else if (session.getAttribute("password") != null) {
                session.removeAttribute("password");
            } else if (session.getAttribute("total") != null) {
                session.removeAttribute("total");
            } else if (session.getAttribute("total0") != null) {
                session.removeAttribute("total0");
            }

%>
    </body>
</html>

is it ok?

Seetharaman Venkatasamy

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posted 14 years ago

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typically, if you ask question clearly, you get clear answer.

coming to your question, what happened when you clicked the *dead* button?. as a side note, avoid scriptlet in jsp which is consider as a bad practice

Samanthi perera

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posted 14 years ago

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what do you mean dead button.
I need to do clear session varibles when click logout button.
is this ok?

Nicola Garofalo

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posted 14 years ago

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I think you need to unbind all the attributes from the session on logout, don't you?
Well, you can write:

Look at HttpSession object API for further details

Bye,
Nicola

Nicola Garofalo

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posted 14 years ago

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Anyway that's not what's going to happen on your jsp.

In your jsp the button in useless, and you are removing attributes from the session

try to do like this:
In your jsp just write

Then you should write a servlet mapped in logoutservlet that invalidates the session

Bye,
Nicola

Samanthi perera

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posted 14 years ago

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anyway it is ok.
i have another problem
is this both are same

Nicola Garofalo

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posted 14 years ago

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They are not the same, it doesn't work like that.

sorry if i repeat it, you should execute logout operation in a servlet, not in a jsp.
Remember, your button is useless in the example you posted: session attributes there are removed in any case.

Bye,
Nicola

Samanthi perera

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posted 14 years ago

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ok
i did what you said.
but why you say

should execute logout operation in a servlet, not in a jsp

what is the wrong with it is doing in jsp?

Nicola Garofalo

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posted 14 years ago

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Because that way of programming is cahotic.
You are doing too many things in one component. You are showing data and performing a key operation as a logout in one jsp.
Always try to keep your operations separated or your application can become really hard to mantain.

There's an architectural pattern called MVC that helps you to avoid such situations. As you will go on programming you will feel the need of following it, it will help you to keep components simpler, easy to mantain and to update, not coupled one to the other.

Bye,
Nicola

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