Spring MVC Tutorials 24 - Interceptor 02 ( more on understanding basics of it...) Video Lecture | MVC Tutorials: Web Programming Course - Web Development

guys my name is Ankush Gaurav and I
welcome you to gone to series this
tutorial is in continuation with the
earlier one where I showed how to use
the concept of an interceptor with the
help of a very simple example in this
damn application so over what I did in
the previous tutorial I included a Java
class with the name D of week based
access interceptor in this application
and also included this code snippet here
in the springs configuration file so
after both these modifications in this
application now when any user would try
to make any web page request with this
application this application is going to
first make a call to this method and if
this method returns true for that
request it's only then the application
would further handle or process that
request and if this method returns false
for that request in that case the
application is going to send the
response back to the clients browser
from here itself without further
handling or processing that request and
all this we learned in a detailed way in
the previous tutorial now let's proceed
further and learn about the same concept
in a little more depth guys in addition
to P handle method handler interceptor
adapter class provides two more
important methods with any post handle
and after completion
so let us override both these methods in
the shower class and later I would
explain in detail what exact purpose
these methods serve to us
cool so here I have overridden post
handle and after completion methods in
this our class which are provided by
handler interceptor adapter class now
let's learn in detail what exact purpose
these two methods serve in a spring MVC
application because what exactly happens
when this method returns true for any
web page requests which comes to this
application the application further
handles our processes that request so
what exactly that means this just means
that application performs two major
steps in order to produce the response
object for that request force it makes a
call to an appropriate request handler
method which would be present in some
control class in the application and
then it makes a call to an appropriate
view file and whatever outcome or
response object you file gives to the
application the application simply
returns that as a response webpage back
to the clients browser for that request
now what if you want your application to
perform some task right after it
executes the request handler method and
also some tasks right after the view
file produces the response object let's
say what I want in this application when
I would make any webpage request to it
and this method returns true then while
processing that request this application
should print this simple message on the
console after it executes the request
handler method for that request and this
simple method after the view file
produces the response object for that
request so question is how we would do
it and the answer is with the help of
post Hetal and after completion methods
because the concept is spring ham is he
makes a call to post handle method after
it executes the request handler method
for a request and it makes a call to
after completion method after the view
file produces the response object for a
request so as per our requirement let us
put this SOP over here and this one over
here and check this working on the
browser after all these modifications
so now if I type this URL and press
Enter
let's see what happens good the
application has sent this response were
paid back to me for this URL now let's
see on the and soul what it has printed
cool the application has printed these
two statements as per our expectation so
what exactly happened when I made a
webpage request to it after all these
modifications that is including post
handle and after completion methods here
after receiving the request the
application first made a call to this
method that is pre handled method
because today is Thursday so this
application returned true and the
application then made a call to this
request and then added after executing
it the application made a call to post
handle method as per our expectation and
printed this message on the console this
force message and then the application
made a call to this view file and when
this view file produced response object
the application made a call to after
completion method as per our expectation
and printed this method on the console
in this second message and then the
application returned the response object
back to me here alright because let's
learn about one more important thing
before I wind up this tutorial in the
springs configuration file if you
observe I included this code snippet so
what exactly this code snippet means
which I included in the previous
tutorial here with this code snippet am
simply instructing spring IOC framework
here spring MVC framework please
consider this interceptor class for
every webpage request which would be
coming to this application now what if
you want this application to consider
this interceptor class for only a
specific URL request and not for every
URL request which would be coming to
this application say for example what
here is this application should consider
this interceptor class only for this URL
and not for any other URL requests so
question is how would do it and the
answer is by making a slight
modification over here you just need to
include this interceptor tag and put the
spin inside it and on top of the spin
you just need to mention for which URL
you want this application to consider
this interceptor class because I want
this interceptor class to be considered
only for this URL request so I would
copy this URL pattern and would paste it
here
so after this modification now this
application is going to consider all
methods of this interceptor class only
for this URL and not for any other you
are requests which would be coming to
this application because in the next
tutorial we will learn how to use the
concept of an interceptor in order to
perform some advanced level tasks in
your spring MVC application like
supporting multiple languages supporting
multiple themes etc etc guys a big thank
you for learning spring MVC 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 various please hit the like button
if you really like this video and do not
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channel
Khan to series and I'm going to catch
you in the next part of this tutorial