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Page 461

Giri Thava
Ranch Hand

Joined: Jun 22, 2006
Posts: 38
Page 461 says that the exception implicit object is available
only to error pages with an explicitly-defined page directive:
<%@ page isErrorPage="true" %>

However, in practice the implicit exception object is available to
the following code (errorPage.jsp):
<html>
<body>
${pageContext.exception}
</body>
</html>

And it is not avaolable to the following code (errorPage.jsp):
<html>
<body>
<%
out.print(exception.getMessage());
%>
</body>
</html>

The page that throws the exception is, badPage.jsp:
<%@ page errorPage="errorPage.jsp" %>
<html>
<body>
<%
int x = 10/0;
%>
</body>
</html>

Please explain me this problem. I am using Tomcat 5 with IE 6.
I searched the forum before posting this, but I cannot find anything useful.

Advance thanks.
Christophe Verré
Sheriff

Joined: Nov 24, 2005
Posts: 14688
    
  16


You are not using the exception implicit object here. What you're doing is access the exception property of the PageContext. The
container will call PageContext#getException, which, like any methods, will always be available. What the book is talking about is the exception implicit object, which you can access like this :

This object is only available to pages which have their isErrorPage attribute set to true.


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Lavanya Mothilal
Ranch Hand

Joined: Dec 27, 2007
Posts: 30
Hi Christophe ,

EL does not have 'exception' as an implicit object. The only way to get the exception object is to go through the pageContext implicit object. So even if a jsp page is declared as an error page (using isErrorPage="true"), ${exception} will not work. Correct me if i am wrong.


Thanks,<br />Lavanya
Christophe Verré
Sheriff

Joined: Nov 24, 2005
Posts: 14688
    
  16

Oops, that's right, thanks for correcting. This implicit object can be accessed via a scriptlet

See Table JSP.1-7 in the JSP Specification for more.
 
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subject: Page 461