Image Source Google Images |
Hello everyone I think everyone celebrate NEW YEAR and Every one
welcoming 2013. I hope this year give lot of joeys and what are dreams in your
mind comes into true. Now see current post is related to filters. My last post I
given some of the Servlet information. Please see all servlet related post
once.
A filter is a container managed object that is declarative
inserted within the request-response cycle of http client and http server. A
filter instances acts as an interceptor. It is a preprocessed of the request
befre it reaches a servlet and a post processor of the response leaving the
servlet. A filter can perform the following.
o
Intercept a servlet’s invocation before a
servlet is called.
o
Examine the request before a servlet is called.
o
Modify the request headers and request data.
o
Modify the response headers and response data.
o
Intercept a servlet’s invocation after the servlet
is called.
A filter object implements javax.servlet.Filter.interface. The interface provides 3 life cycle
methods.
Public void
init(FilterConfig):- Servlet engine calls this method only once
after instantiating the filter. Initialization parameters are encapsulated in
the FilterConfig object. By calling getInitParameter method in the
FilterConfing object we can retrieve them. This method must complete successfully
before the filter is asked to day any filtering work.
Public void
doFilter(ServletRequest,ServletResponse,FilterChain):- It is
called by the container each time a request/ response pair is passed through
the chain due to a client request for a resource at the end of the chain. The
FilterChain passed into this method allows the filter to pass on the request
and response to the next entity in the chain.
Public void
destroy():- Called by the servlet engine to indicate to a
filter that it is being taken out of service. This method gives the filter an
opportunity to clean up any resources that are being held. For example, closing
of the database connection.
Hey common
you know my principle why you need to study all the mater right just watch the following
video you can understand better way what are the Servlet Filters, right then why late start the following
video. Once again HAPPY NEW YEAR 2013.
Post a Comment
Post a Comment