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Check for a variable if it's available on the server

Posted on 2004-08-14
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Last Modified: 2012-05-05
I want the statement that check if a specific variable is available on the server variables or not.

I need that in order to check for the availability of a specific variable. So that if the any one reached the page directly i can display my own message instead of null pointer exception raised by the compiler
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Question by:The_Gutsy
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4 Comments
 
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sbockelman earned 500 total points
ID: 11801237
String sExpectedVariableValue = request.getParameter( "theExpectedVariables" );
if( null == sExpectedVariableValue ) {
    // kick them out!
}

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by:pat5star
pat5star earned 500 total points
ID: 11818378
You should store a specific word in the users session from your main entry page, like a login page.

HttpSession session = request.getSession();
session.setAttribute("secretWord", "secret");

Then on every page that you only want 'logged in' users you check for the secretWord like this:

if (null != session.getAttribute("secretWord") && "secret".equals((String)session.getAttribute("secretWord"))) {
  // They are logged in
} else {
  // They are not logged in, send error message...
}

What this does is check that the session attribute "secretWord" is not null and that it does equal the value "secret". If not, you know they came to the page directly and can then handle it whatever way you want.

Hope that helps,

-Pat
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