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From Brian Cook <>
Subject Re: fileUpload NullPointerException
Date Fri, 11 Jul 2003 19:33:50 GMT
item.write(fileName) Is the method that will throw FileUploadException 
if no actual file is returned.  i.e. A blank file input type

FileUpload.parseRequest(request)  Will throw Exceptions if it can not 
read the POST data, or write to disk.

> "Jakarta Commons Users List" <> writes:
>>I am guessing the instance you described with three file upload fields 
>>falls into one of the following
>>	o All three file input fields have the same name. Which would return 
>>only one file name.
> They are unique. I have another page with only one upload field. If you
> put nothing in it is does not throw an exception.
>>	o There is some scripting on the client side to account for it.
> You mean browser scripting? I assume that if you don't put anything in it,
> the browser does not submit the field (that is, the browser doesn't try to
> encode nothing for an upload).
>>	o You have a test at some point in your code to skip the file upload if 
>>the form does not return a file name to the servlet.
> Here's my servlet code (in request wrapper) that parses the request:
> 	DiskFileUpload upload = new DiskFileUpload();
> *	List items = upload.parseRequest(this, memoryLimit, fileSizeLimit,
> savePath);
> 	Iterator iter = items.iterator();
> 	while (iter.hasNext()) {
> 		FileItem item = (FileItem);
> 		if (item.isFormField()) {
> 			String key = item.getFieldName();
> 			String value = item.getString();
> 			setParameter(key, value, false);
> 		} else {
> 			fileUploadItems.put(item.getFieldName(), item); // save to a HashMap
> for later use
> 		}
> 	}
> What I seem to be hearing is that the line with the * is supposed to throw
> an exception if you don't enter anything into the upload field. I don't
> see how a developer could possibly make use of FileUpload if that were the
> case - there would then be no means to use the rest of the parameters to
> do something other than crash miserably.
> Is it a call to item.write() that would fail if nothing were uploaded?
>>	o The servlet does not actually write the file to disk so the 
>>fileItem.write(fileName) method is not actually called.
> That's true, I guess. There is no FileItem that makes it into my HashMap,
> so I never call write on it.
> It seems to me that if you don't put anything in the file upload control
> on the page, the browser doesn't send anything for it and FileUpload never
> sees it in the request and everything works as if there was never a file
> upload control on the page in the first place.
> Daryl Stultz
> _____________________________________
> 6 Degrees Software and Consulting, Inc.
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