2.2. Overview of Spring MVC Architecture¶
Index
Official website of Spring MVC says the following
Spring’s web MVC framework is, like many other web MVC frameworks, request-driven, designed around a central Servlet that dispatches requests to controllers and offers other functionality that facilitates the development of web applications. Spring’s DispatcherServlet however, does more than just that. It is completely integrated with the Spring IoC container and as such allows you to use every other feature that Spring has.
2.2.1. Overview of Spring MVC Processing Sequence¶
The processing flow of Spring MVC from receiving the request till the response is returned is shown in the following diagram.
DispatcherServlet
receives the request.DispatcherServlet
dispatches the task of selecting an appropriatecontroller
toHandlerMapping
.HandlerMapping
selects the controller which is mapped to the incoming request URL and returns the(selected Handler)
andController
toDispatcherServlet
.DispatcherServlet
dispatches the task of executing of business logic ofController
toHandlerAdapter
.HandlerAdapter
calls the business logic process ofController
.Controller
executes the business logic, sets the processing result inModel
and returns the logical name of view toHandlerAdapter
.DispatcherServlet
dispatches the task of resolving theView
corresponding to the View name toViewResolver
.ViewResolver
returns theView
mapped to View name.DispatcherServlet
dispatches the rendering process to returnedView
.View
rendersModel
data and returns the response.
2.2.2. Implementation of each component¶
Among the components explained previously, the extendable components are implemented.
2.2.2.1. Implementation of HandlerMapping¶
Class hierarchy of HandlerMapping
provided by Spring framework is shown below.
Usually org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping
is used. This class reads @RequestMapping
annotation from the Controller
and uses the method of Controller
that matches with URL as Handler class.
In Spring3.1, RequestMappingHandlerMapping
is enabled by default when <mvc:annotation-driven>
is set in Bean definition file read by DispatcherServlet
.
(For the settings which get enabled with the use of <mvc:annotation-driven>
annotation, refer
Web MVC framework.)
2.2.2.2. Implementation of HandlerAdapter¶
Class hierarchy of HandlerAdapter
provided by Spring framework is shown below.
Usually org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter
is used.
RequestMappingHandlerAdapter
class calls the method of handler class (Controller
) selected by HandlerMapping
.
In Spring 3.1, this class is also configured by default throught <mvc:annotation-driven>
.
2.2.2.3. Implementation of ViewResolver¶
Classes that implement ViewResolver
provided by Spring framework and dependent libraries are shown below.
Normally (When JSP is used),
org.springframework.web.servlet.view.InternalResourceViewResolver
is used,
however, when template engine Tiles is to be used
org.springframework.web.servlet.view.tiles3.TilesViewResolver
and when stream is to be returned for file download
org.springframework.web.servlet.view.BeanNameViewResolver
Thereby, it is required to use different viewResolver based on the type of the View that needs to be returned.
View
of multiple types is to be handled, multiple definitions of ViewResolver
are required.ViewResolver
is the screen application for which file download process exists.View
is resolved using InternalResourceViewResolver
and for File download View
is resolved using BeanNameViewResolver
.2.2.2.4. Implementation of View¶
Classes that implement View
provided by Spring framework and its dependent libraries are shown below.
View
changes with the type of response to be returned. When JSP is to be returned, org.springframework.web.servlet.view.JstlView
is used.
When View
not provided by Spring framework and its dependent libraries are to be handled, it is necessary to extend the class in which View
interface is implemented.
For details, refer File Download.