Follow the steps of this article: codejava.net/coding/upload-files-to-database-servlet-jsp-mysql.
Http servlet and Generic servlet
Servlet Chaining means the output of one servlet act as a input to another servlet. Servlet Aliasing allows us to invoke more than one servlet in sequence when the URL is opened with a common servlet alias. The output from first Servlet is sent as input to other Servlet and so on. The Output from the last Servlet is sent back to the browser. The entire process is called Servlet Chaining.
A JSP is typically oriented more towards displaying information, and a servlet is more oriented towards processing information. For example, a JSP might display a report, while a servlet would process a user submitted form. These uses are not exclusive, but they are optimized more for performing tasks in this manner. It is much easier to incorporate HTML coding into a JSP than a Servlet. It is also easier to write more complex Java code in a servlet.