Filters are used to process requests and responses in servlets. Filters intercept requests before they reach servlets and responses after they leave servlets. This allows filters to perform functions like authentication, logging, compression, and more across multiple servlets. To create a filter, we implement the Filter interface and define init(), doFilter(), and destroy() methods. The doFilter() method contains the main filtering logic and can pass the request and response to the next filter or servlet in the chain. Filters are configured in web.xml and can be chained to customize request and response processing.

2. Requestsbefore the servlet was processed

7. User actions

8. Compress the output streams

9. Very flexible because we won’t write the filters within servlets

12. init( )

13. doFilter( )

16. Write the processes for filtering Used to provide any configuration parameters

18. Request

19. Response

20. Object of FilterChain

21. Also called by the web container

22. Does all the filter processes

24. Otherwise it will do post processing - filtering the response

26. General Formpublic void destroy( ) { //write your codes }

28. What are Servlet Filters ? doFIlter( req, res, chain) { chain.doFilter(req, res) } To process the request or to filter the request Codes to filter the request To intercept the servlet output or to filter the response Codes to filter the response