Use of HttpServlet over GenericServlet

[Jigar Naik]

What is the need for having HTTPServlet class when we already have GenericServlet class which can handle all type of requests?

[Ulf Dittmer]

HttpServlet adds capabilities to GenericServlet (which knows nothing about HTTP). For example, it can discriminate between the various HTTP methods. If you were to use GenericServlet then your code would have to do that instead.

[Mathew Lee]

Here are some of uses of HttpServlet over GenericServlet:

GenericServlet is for servlets that might not use HTTP, like for instance FTP servlets. Of course, it turns out that there's no such thing as FTP servlets, but they were trying to plan for future growth when they designed the spec.

In short GenericServlet is protocol independent, whereas HttpServlet is protocol dependent

In GenericServlets you cannot use Cookies or HttpSession.
Session tracking is not possible, redirection is not possible.

Http servlets overrides doGet and doPost methods. Generic servlet overides service method.

[Bear Bibeault]

Short version: use HttpServlet.

[Deepak Bala]

Further you can have a look at the HTTP specific methods to understand the difference. Cookies for example, make sense with Http only and cannot be included into the generic servlet