In order to
define a Servlet, implementation of Servlet interface is need to be provided.
This
Implementation can be provided in 2 ways:
1- Direct
2- Indirect
1- Direct
2- Indirect
In order to
facilitate indirect implementation of Servlet interface, SUN Microsystems
provide a helper class named javax.servlet.GenericServlet.
It is an abstract class which
implements Servlet interface and defines all its method except service ().
Both approaches
are not usually used because it has following limitations:
Servlet interface and its implementation in GenericServlet class are protocol
independent in web application. Some protocol (HTTP, HTTPS) used by the client
to interact with the web server. Each of these protocols supports different
types of request.
Most
commonly used protocol is HTTP which supports following 8 types of request.
Types of HTTP request:
1- get
2- post
3- put
4- delete
5- head
6- trace
7- connect
8- options
To remove
the mismatch between request processing model of Servlet and HTTP protocol, HTTP specific extension of GenericServlet class is provided by SUN
Microsystems.
javax.servlet.http package contains http specific interfaces and classes of Servlet
API. This packae contains HttpServletRequest
and HttpServletResponse interfaces
which extends ServletRequest and ServletResponse interfaces
respectively.
An HTTP
specific helper class is defined in javax.servlet.http
package by the name HttpServlet.
HttpServlet class extends GenericServlet and provides methods for handling each type of HTTP request.
HttpServlet class extends GenericServlet and provides methods for handling each type of HTTP request.
Most
commonly used method of this class are doGet()
and doPost() these are used to process HTTP get and post request
respectively.
1- public void
doGet(HttpServletRequest request, HttpServletResponse response) throws
ServletException;
2- public void doPost(HttpServletRequest
request, HttpServletResponse response) throws ServletException;
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