What is servlet? An Introduction to Java Servlets

The basic aim of servlet is to develop web applications.  Before servlets came into picture there was a specification called CGI.  Servlets specification developed by SUN and released to the industry.   Lot of server vendors came forward for implementing these specifications of servlets.  Servlets are nothing but set of rules given by SUN in the form of Interfaces.  The server vendors have developed their own classes by implementing the interfaces developed by SUN.

The collection of classes developed by server vendors and Interfaces developed by SUN are known as Servlet-API.

What is servlet

A servlet is a server side platform independent, dynamic and multithread java program, which runs in the context of server for extending the functionality of server.  When multiple users make a request to the same servlet then all requests will be processed by the container by creating multiple threads for the same servlet. In order to deal with these servlet programming, we must import

javax.servlet.*;
javax.servlet.http.*;

into our java program.

• javax.servlet.Servlet is one of pre-defined top most interface, which is containing life cycle methods[init(), service(), destroy() i will describe about these methods later] for servlet.
• javax.servlet.GenericServlet is one of the predefined abstract class which is implementing javax.servlet.Servlet interface,  this GenericServlet class is used for developing protocol independent applications [ But in real time we will use protocol dependent applications only, so GenericServlet won’t be appeared in real time ]
• Javax.servlet.http.HttpServlet is sub class of GenericServlet used for developing protocol dependent application  [ HTTP protocol ]

Consider Myserlet.java is our own class always recommended to extends HttpServlet servlet, as our current internet world is supporting HTTP protocol right 🙂  In real time, we will use HttpServlet only not GenericServlet remember.

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• Example on getParameterNames() method of Servlet Request Object

::. About the Author .::
		Sivateja Kandula - Java/J2EE Full Stack Developer Founder of Java4s - Get It Yourself, A popular Java/J2EE Programming Blog, Love Java and UI frameworks. You can sign-up for the Email Newsletter for your daily dose of Java tutorials.