The FileUpload user guide at http://commons.apache.org/fileupload/using.html is very helpful. I suggest extending it with a tiny example of a HTML form that will work suitably. I left off the "enctype" attribute on my form so naturally nothing worked properly, the call (from the user guide) to ServletFileUpload.isMultipartContent(request) always returned false. A web search gave me the answer; e.g., here in the Oracle/Sun forum http://184.108.40.206/thread.jspa?messageID=10697258
All that's needed is a tiny example like this:
<form action="upload_file.jsp" method="post" enctype="multipart/form-data" name="form1" id="form1">
Choose file: <input name="file" type="file" id="file"/>
<input type="submit" name="Submit" value="Submit files"/>
Thanks for listening.