Spring MVC Tutorials 08 - MultiAction Controller class; @RequestMapping annotation at class level Video Lecture | MVC Tutorials: Web Programming Course - Web Development

guys my name is Akash Gaurav and I
welcome you to gone to series in the
previous tutorial I talked about
creating a simple web application using
spring MVC provided annotations I showed
you how to write a controller class
using controller and request mapping
animations while writing the controller
class I very clearly explained you the
purpose of putting a request mapping
annotation on top of a method which is
reciting in a controller class the idea
is very simple and clear if you want
this method to be invoked by the front
controller when a client enters a URL on
the browser then its request mapping
pattern has to match with the incoming
grass URL pattern so if the incoming
requests you are a pattern is something
like this then the front controller
would invoke this method for further
processing the request only after
finding that the request mapping pattern
of this method is matching up with the
URL pattern of this incoming URL request
the method which you right here in the
controller class for the purpose of
handling and incoming requests is in
general called as a request handler
method by spring MVC framework so what
happens if I put one more request
handler method in the same controller
class with the name hi world and with
the request mapping pattern like this
nothing special it just a concept in
spring MVC framework that you can write
as many request handler methods in a one
controller class as you like so in this
case if a client is going to type this
URL on the browser then the front
controller would make a call to this
method for further processing the
request and if the client types this URL
then the front controller would make a
call to this method for further
processing the request it simply means
it would just match up
this request mapping pattern which you
mention on top of a method with an
incoming request pattern and makes a
call to the corresponding method any
controller class having more than one
request handler method in it is called
as a multi action controller class so
what's a multi action controller class
it's simply a controller class having
more than one request handler methods in
it and nothing more before we proceed
further and tell you for the concepts
let me tell you one very important point
here what if your client types this URL
on a browser if you notice here it's
your a pattern it is not matching up
with the request mapping patterns which
are available in this controller class
on each method in this case the
application will return a response back
to the client browser saying there is no
resource available on the server which
can process this request let me run it
and show you how this works
type this URL Center so I type the URL
for which there is no matching request
mapping annotation pattern is present in
the controller class in the application
and the application simply returned the
requested source is not available for
not forever
good let's proceed further because there
is a provision in spring MVC framework
that you can put the request mapping
annotation on top of a class tool so if
I put the request mapping annotation
with this pattern at the class level
also what it means there is something
known as a relative and an absolute path
in the programming word earlier you used
to type this URL and the front
controller used to make a call to this
method and for this URL the front
controller used to make a call to this
method but now if you type these URLs
again on the browser the front
controller would not be able to process
your request and it will send you back
the resource is not available to process
these requests and the reason is this
annotations presence at the class level
now the request mapping annotations
which you are mentioned here on the top
of methods are related to this
annotations pattern what it means is now
if you want to make a call to this
method for aur request then the URL
request should look like this and if you
want to make call to this method then
the request should look like this means
this pattern has to be there in the URL
before the individual methods URL
pattern let me find this example on the
server and show you how this thing works
here the application is already running
on the server and has taken all these
changes dynamically which I just made so
let me state forward go to the browser
and test this application paste this URL
if you observe here this is the earlier
URL which I used to type before putting
this annotation on top of the hello
controller class so ideally now it
should return me resource is not
available yes it has sent me the
response as per my expectation now I
change this URL to have greet pattern
present before welcome
cool this time application has happily
sent me the response using this method
and same is applied to this method if I
want to make a call to this method then
I have to use this pattern before this
pattern in the incoming request you are
in the subsequent tutorials we will
learn more about request mapping and
patient while talking on different
concepts in spring MVC framework guys
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tutorial