Help in getting the URL string.

Question

Hi:
In my project, when click on a Product link it will go to the login page asking for name and pwd . I passed the URL of the page where the link is present to the login.jsp . In login.jsp , I captured the URL querystring . After clicking the submit button in the login page, I expect the control should go directly to the page where the link is present. So I use response.sendRedirect("linkpage.jsp?"+querystring);
But it says NullPointerException in linkPage.jsp because the query string captured is null.
Can anyone tell me why I get the querystring as null value.
Thanks.

Answer 1

Yes. Thanks for understanding . Here are the details:
I have 2 pages:
view.jsp
login.jsp
I try to access http://localhost:8080/view.jsp . It redirects to login.jsp for user authorization. So I do the following:
In view.jsp:
response.sendRedirect("/login.jsp?querystring="+sq+"&ret_page="+spage);
In login.jsp:
sQuerystring=request.getParameter(querystring);
sPage=request.getParameter(ret_page);
if (sQuerystring!=null || sQueryString!=" ")
response.sendRedirect(sPage+"?"+sQueryString);
else
response.sendRedirect("defaultpage");
When I run this pgm,it says nullpointer exception and forward() not allowed after the buffer is submitted.
Could you give me a solution.
Thanks.