What are the differences between GenericServlet and HttpServlet?

GenericServlet is an abstract base class that provides common functionality for all servlets. It is protocol-independent. The main request handling method is service(ServletRequest req, ServletResponse res).

HttpServlet is an abstract class that extends GenericServlet and is specifically designed for working with HTTP requests. It provides methods for handling various types of HTTP requests (GET, POST, PUT, DELETE, etc.): doGet(), doPost(), doPut(), doDelete(). The service method in HttpServlet is overridden to dispatch HTTP requests to the corresponding doXxx() methods.

Main differences:

Feature	GenericServlet	HttpServlet
Protocol	Protocol-independent	HTTP-oriented
Main processing method	service(ServletRequest, ServletResponse)	service(HttpServletRequest, HttpServletResponse). Calls doGet, doPost, etc.
Request types	Handles general requests	Specialized handling of HTTP methods (GET, POST, PUT, DELETE, etc.)
Abstraction	Lower level of abstraction	Higher level of abstraction for web

GenericServlet is suitable for creating servlets that work with protocols other than HTTP or for creating specialized base classes for servlets. HttpServlet is used in the vast majority of Java web applications for handling HTTP requests.