enctype multipart form-data input-field Access

Question

I have a JSP-Page with a form with enctype="multipart form-data:

<form enctype="multipart/form-data" name="upLoadForm" method="post" action="aktionFileUpload.do">
<input type="file" name="userfile_1" id="file_element"/>
<input type="hidden" name="parameterHelper" id="parameterHelper" value="test"/>                     
</form>

The file upload in my servlet works, but I get no access to the input field with:

 request.getParameter("parameterHelper");

I searched in the internet and there I found that the servlet recieves it as MIME-Type or such other thing. But I did not find any solution, so that I can read the field.

Can you Help me?