Why filters are used in servlets

Filter interface provides the life cycle methods for a filter. The object of FilterChain is responsible to invoke the next filter or resource in the chain. This object is passed in the doFilter method of Filter interface. The FilterChain interface contains only one method:. For mapping filter we can use, either url-pattern or servlet-name. The url-pattern elements has an advantage over servlet-name element i. In this example, we are simply displaying information that filter is invoked automatically after the post processing of the request.

JavaTpoint offers too many high quality services. Mail us on [email protected] , to get more information about given services. Please mail your requirement at [email protected] Duration: 1 week to 2 week. Servlet Tutorial. War File welcome-file-list Load on startup. Servlet Collaboration. RequestDispacher sendRedirect. Servlet Advance Session Tracking. Step Configure Filter class in web. A filter is an object available at server machine, it must implement Filter interface either directly or indirectly.

While executing a particular Filter in web applications, if we satisfy all the Filter constraints then we need to bypass the request from the present Filter to the next Filter web resource, for this we need to use the following method from FilterChain. While executing a particular web application, when a container identifies a particular Filter to execute, then the container will execute that Filter by following the Filter life cycle.

In web applications, by default, all the filters are auto-loaded, auto-instantiated, auto-initialized at the time of server startup. So that Filters should not require load-on-startup configuration in web. To configure a filter in the web. In web applications, it is possible to use a single Filter for multiple numbers of web resources. There are 3 types of filters:.

Note: Filter program and its target servlet program or JSP program uses the same request, response object. So, the filter program can send data to the servlet program or JSP program by using request attributes. There are three interfaces of Servlet API:. It takes one parameter, i.

FilterConfig type or FilterConfig object. This method is considered the most important method in the Filter interface. It performs some important tasks like.

The container invokes this method to indicate the filter is finished its task or the filter is taken out from service. Users can override this method to writing some finalizing codes like freeing some resources, objects, etc. We have seen the advantages of filters; it clearly denotes that using filters in servlet is best suitable for developing web applications where the request and response processing is faster and filtered or intercepted.

Most of the cases using filters help in server-side coding. Please provide weblogic server version too. Something missing in your project! How to prevent to got logged in page after back button pressed? But this is a good article! Can you please give an example on how to redirect to logout page when Session expires due to inactivity.

I have been following most of your tutorials. Thank you for your time. Keep up the good work. Your email address will not be published. Download Servlet Filter Example Project. Pankaj I love Open Source technologies and writing about my experience about them is my passion. Follow Author.

Comments Stephan says:. March 29, at pm. Sathish says:. October 28, at am. Akila says:. March 19, at pm. Rajanikant says:. October 3, at pm. Ameet says:. June 12, at am. Pankaj says:. June 12, at pm. Mohit Patidar says:. February 25, at pm. Parth says:. November 16, at am. Art says:. July 17, at am. Trabelsi chaima says:. June 28, at pm. Suxin says:. June 2, at pm. Ron says:. February 8, at am.

June 15, at am. Andrey says:. August 21, at pm. Hakim Pocketwalla says:. April 15, at pm. Jitendra says:. May 19, at am. Tip says:. May 2, at am. Enes says:. March 21, at am. Decebal says:. December 10, at am. Jon Snow says:. September 7, at pm. Prashant Chaudhari says:. June 30, at pm. Selvaraj says:. November 21, at am. Rainer says:. July 14, at am.