The Apache Commons open source project includes various useful components we can use in our code. One of them is the FileUpload, that allows us to develop a Java Servlet (or a JSP document) that handles files uploads.
The following video clip presents a small code sample for handling a file upload coming from an HTML file. You can find the source code as well as more explanations in the Introduction to Apache Commons course I have recently started to develop for free personal and academic usage at www.abelski.com.