Hi,
I have a problem when I want to upload a file. First I have a page for
Broswer to select the file. then go to a confirmation page to tell user if
the file name is the one user wanted(display the filename), if user confirms
it and press the next button, at that time, server will upload the data to
database. My problem is when user click the next button, sometimes it works
fine, sometimes it throws exception.(null pointer exception). when I click
back button in Browser, it give me the messages: Warning: Page has Expired
The page you requested was created using information you submitted in a
form. This page is no longer available. As a security precaution, Internet
Explorer does not automatically resubmit your information for you.
To resubmit your information and view this Web page, click the Refresh
button.
I use the following code to forward the form to the next confirmation action
class:
UploadForm theForm = (UploadForm) form;
if("request".equals(mapping.getScope())) {
request.setAttribute(mapping.getAttribute(),theForm);
}
So I guess the problem is during the confirmation process, teh page expired,
so the file with the form is null, it throws null pointer exception. but I
don't know how to fix it . Please help me out.
Thanks in advance.
Gang Gao
