Servlet API by R4R Team

Servlet API
Servlet API consist of two important packages that encapsulate all the important classes and interface.

1)javax.servlet
2)javax.servlet.http

Some Important Classes and Interface of javax.servlet

CLASSES INTERFACES
Servlet ServletRequest
ServletResponse  ServletConfig
ServletContext RequestDispatcher
FilterChain Filter
ServletInputStream  GenericServlet
ServletOutputStream  ServletException


Some Important Classes and Interface of javax.servlet.http

CLASSES
 
and INTERFACES
 
HttpServlet HttpServletRequest
 
HttpServletResponse HttpSessionAttributeListener
 
HttpSession  HttpSessionListener
 
Cookie  HttpSessionEvent
 

Servlet Interface:
Servlet Interface provides five method. Out of this five method three method are servlet life cycle method and rest two are non life cycle method.

servlet interface example
GenericServlet Class

GenericServlet is an abstract class that provide implementation of most of the basic servlet method.

Methods of GenericServlet class

public void init(ServletConfig)
public abstract void service(ServletRequest request,ServletResposne response)
public void destroy()
public ServletConfig getServletConfig()
public String getServletInfo()
public ServletContext getServletContext()
public String getInitParameter(String name)
public Enumeration getInitParameterNames()
public String getServletName()
public void log(String msg)
public void log(String msg, Throwable t)
HttpServlet class

HttpServlet is also a abstract class. This class gives implementation of service() method of Servlet interface.

To create a servlet, we should create a class that extends HttpServlet abstract class. The servlet class that we will create should not override service() method. Our servlet class will override only doGet() and/or doPost() method.

The service() method of HttpServlet class look at the Http method(GET, POST etc) from request stream and invokes doGet() or doPost() method based on Http method.

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