Spring MVC Tutorials 23 - Interceptor 01 ( Introduction with a hands on session ) Video Lecture | MVC Tutorials: Web Programming Course - Web Development

guys my name is Lankesh Gaurav and I
welcome you to gone to series so far we
learn all about form validation related
concepts using this ultra simple demo
application which I created step by step
along with you in all the previous
tutorials now in this tutorial we're
going to learn about a very important
concept which is supported by spring MVC
framework and that is the concept of an
interceptor and I'm going to use this
same demo application to explain
everything about this concept so let's
start because many times on internet you
would have observed when you try to
access some website sometimes you do not
get the desired web page for that
request instead you get a simple message
on the response web page the website is
closed for maintenance for some hours or
the website is not working at the moment
please try accessing it after some time
or any search similar message now what
if you want to do kind a similar thing
for this time application - let me
explain my requirement in detail what I
want is this application should work on
all weekdays except for Sunday so in
short what I want is when any user
requests for a web page with this
application at that moment before
handling that request this application
should perform a simple task of checking
whether the request is made on Sunday or
any other retail if it is made on Sunday
then this application should not perform
any processing for that request and
should return back this simple message
back to the user as a response webpage
the website doesn't work on Sunday
please try accessing it on any other
vitae and if it is made on any other
retail then this application should
perform all the steps which are needed
to handle that request that is first
make a call to an appropriate request
handler method along with performing all
other steps for producing the desired
webpage for that it was
so question is how we would achieve such
a typical requirement in this time
application and the answer is using the
concept of an interceptor which is
provided by spring embassy swing work
then spring embassy says he developers
for a requirement like this where you
want your application to perform some
task before it starts handling or
processing the request you simply need
to follow these three simple steps and
you will be done the first step which
you need to perform is just include a
Java class which extends handler
interceptor adapter class and overhead
one of its methods for the name pre
handle in this chava class and then
write the code inside the pea handle
method of this Java class which you want
spring embassy to execute before
handling the request and last but not
the least just let's ping embassy know
about this Java class by putting its
entry in the strings configuration file
that is in the spring dispatcher server
dot XML file and that's it so let us
perform these three steps one by one to
satisfy this project's requirement and
later after performing all these three
steps have explained the whole concept
in detail to you so here I have included
this new Java class in this application
with the name D of weekdays access
interceptor which extends handler
interceptor adapter class and overrides
one of its methods with the name we
handle in it exactly as for the first
step which is suggested by spinning
embassy framework here now the concept
is when any user would request for a web
page to this application at that moment
before handling that request spring MVC
framework is going to make a call to
this method and the concept is if this
method would return to its only then the
application would for the handler or
process that requests and if this method
would return false in that case the
application would not process or
that request further and would send back
the response back to the clients browser
from this method itself so let us
perform the second step by putting the
code which we want spring MBC to execute
for every request before handling it
cool so now the only step which is
remaining here is to let spring embassy
know about this class so for that go to
the springs configuration file and
include this code snippet so with this
code snippet over here in the springs
configuration file
I'm simply instructing setting embassy
fever here spring MVC framework in this
application I have included a Java class
with a name day of week base access
interceptor so please consider this
class while you handle or process any
requests
so after including this Java class and
this code snippet over here in the
spring time creation file now when any
user would request for any web page to
this application at that moment if the
request is made on Sunday then the
application should return back this
simple message back to the user as a
response web page and if the request is
made on any other weekday then the
application should process our request
in the normal way as it usually does to
process that request so today is Sunday
guys and if I would make this equation
the application then let's see what I'm
cool the application has sent this
message back to me the website is closed
on Sunday please try accessing it on any
other victim because of this method
which we have written over here now if I
change my system date to any other day
other than Sunday let's see what happens
in that case
so I would make it Saturday
now if I make a request for the same
webpage let's see what happens
cool so the application has returned
back the desired package for this
request and white has sent back the
desired webpage because for this request
spring MVC application executed this
method and after executing this method
it found that the request was made on
Saturday and for Saturday it returned
true and after returning to its simply
made a call to this request handler
method and after this it made a call to
this view file and after that whatever
response object this we file generated
it's simply returned back to me as a
response back bit and I got this webpage
because in this tutorial I just meant
introducing you to the concept of an
interceptor with spring MSE supports in
the next tutorial we will learn about
some more basics about this concept
unladen i'll show you some of the
advanced things which you can do using
this concept like supporting multiple
languages supporting multiple themes etc
etc as a big thank you for learning
spring Amasa with me if you have any
feedback or comments please provide them
below the video or simply write to me on
this email id for all of your queries
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series and I'm going to catch you in the
next part of this tutorial