jsp:forward doubt

[sanla palati]

Hi,

I got this question.

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Assume that in your JSP page, you need to forward the request to another page. The url to this page is given by a request parameter named 'redirectto'.

Which of the following code snippets do the above task?



1.<jsp:forward page="request.getParameter('redirectto')" />

2.<% request.getRequestDispatcher( request.getParameter("redirectto") ).forward(request, response); %>

3.<jsp:forward page="%=request.getParameter('redirectto')%" />

4.<jsp:forward page="<%=request.getParameter('redirectto')%>" />

5.<jsp:forward page="%request.getParameter('redirectto')%" />

i thought 2& 3 would be correct answeres. But 2,3,&4 are right. Any comments ? please

Thanks,
Sanla

[Musab Al-Rawi]

I can see why 2 & 4 are correct. In 4 you are getting the value of a parameter and then you use it in jsp:forward, the expression <%= %> will print the value of our parameter.

now I can't get 3
%=request.getParameter('redirectto')% doesn't look like a valid expression, where are the < & >, shouldn't we use them here (like number 4)?

[sanla palati]

even i am thinking same. but dont have any idea why the answere 3 i right

[John Stone]

jsp 2.0 spec. 6.2.2.

Scriptlet expressions used to specify request-time attribute values use a
slightly different syntax in JSP documents than in non JSP documents; rather
than using <%= expr %>, they use %= expr %.

[Gurukant Desai]

John, So you mean to say that only option 3 "<jsp:forward page="%=request.getParameter('redirectto')%" />
)" is right and option 4 "<jsp:forward page="<%=request.getParameter('redirectto')%>" />" is wrong?
Because I think both 3 and 4 are right..
Please clarify...

[sanla palati]

Hi John,

Thanks or your clarification.

Thanks,
Sanla

[John Stone]

Because I think both 3 and 4 are right..

Both should be right,.. but 3 should be OK only in JSP documents (JSP with XML syntax)

[Vijay Bharghav bheemineni]

Thanks John, I would have never thought 3 would be right answer, If I wouldn't had seen this post.

Vijay Bheemineni.