Why request.getParts() returns empty in servlet

[Nam Ha Minh]

Guys, I am stuck at a very strange behavior: I am writing a servlet for handling file upload, using @MultipartConfig annotation for the servlet. I inspected that this statement:

request.getParts()

always returns an empty collection, even I had pick up a file in the upload form. Also the form declares enctype="multipart/form-data" already.

It's strange because I worked before but suddenly it doesn't work anymore today.

My environment is Win7-64-bit, Tomcat 7-64bit, Java 7-64bit.

Any suggestions are greatly welcome.

Thanks.

[Nam Ha Minh]

Guys, I found where is the problem. I change code from:

<input type="file" />

to

<input type="file" name="file" />

I don't know why the attribute "name" matters here. Anyway, that could help if someone experiences the same problem like me.

[Ulf Dittmer]

I think -not quite sure- that elements without a name attribute are not sent as part of the form submission. or maybe that's browser-dependent behavior.

[Nam Ha Minh]

Ulf Dittmer wrote:... maybe that's browser-dependent behavior.

without "name" attribute, it doesn't work with all Firefox, Chrome and IE.

[Bear Bibeault]

Ulf is correct. Unnamed form elements do not participate in the submission.