Spring MVC 3.0 Framework

copyright © I-Admin
Spring Framework 3.0 MVC
Prepared By:
Ravi Kant Soni
Sr. Software Engineer | ADS-Bangalore
session - 1

Objectives
 Introduce Spring MVC Module
 Learn about Spring MVC Components
(Dispatcher, Handler mapping, Controller,
View Resolver, View)

What Is Spring?

What is Spring?
 Spring is light weight, open source framework begins
developed by Spring Source Company
 Spring 1.0 was released in 2004
 Spring is available on www.springframework.org
 It provides support for JPA, Hibernate, Web services,
Schedulers, Ajax, Struts, JSF and many other
frameworks

Why use Spring?
 Spring was created to reduce the complexity
observed in Java enterprise application development
 Spring is organised into many modules that offer
various types of assistance to the developer in a host
of application areas
• Spring enables developers to develop enterprise-
class applications using POJOs
• Testing an application written with Spring is simple
because environment-dependent code is moved into
this framework

By the way, just what is MVC?
 Model-View-Controller or MVC is an architectural
pattern used in development of applications.
– Model encapsulates the raw data
– Controller responds to events, and instruct the model and view to
perform actions based on events
– View render information supplied by model in a form suitable for
user interaction.

MVC Architecture

Spring MVC Architecture
 Based on existing Servlet/JSP technology

Spring MVC Components
 DispatcherServlet responsible for intercepting the
request and dispatching for specific urls.
 Controller responsible for processing user requests
and building appropriate model and passes it to the
view for rendering
 View interface represents presentation logic and is
responsible for rendering content
 ModelAndView class objects encapsulates view and
model linking
 Model encapsulates the application data, will consist
of POJO

DispatcherServlet
 Used to handle all incoming requests and route them
through Spring
 Also responsible to initialize the frameworks
components which are used to process the request
at various stages
 Uses customizable logic to determine which
controllers should handle which requests
 Forwards all responses to through view handlers to
determine the correct views to route responses to
 DispatcherServlet Architecture uses the Front
Controller Design Pattern

DispatcherServlet Architecture

DispatcherServlet Mapping
 Request that are to be handled by DispatcherServlet
are to be mapped using a URL mapping in web.xml
config file.
 Each DispatcherServlet has its own
WebApplicationContext

DispatcherServlet in web.xml
 Dispatcher Servlet named "spring" that will intercept all urls to this web
application
 <servlet-mapping> tag indicates what URLs will be handled by the which
DispatcherServlet
<servlet>
<servlet-name>spring</servlet-name>
<servlet-class>
org.springframework.web.servlet.DispatcherServlet
</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>spring</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>

Spring Configuration
 By default Spring looks for a servletname -servlet.xml file in /WEB-INF
 For the previous example we would need to create a file in /WEB-INF named
spring-servlet.xml
<beans xmlns …….>
<mvc:annotation-driven/>
<context:component-scan base-package="com.iadmin.spring" />
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/jsp/" />
<property name="suffix" value=".jsp" />
</bean>
</beans>

Spring Configuration cont..
 <mvc:annotation-driven /> tells Spring to support
annotations like @Controller, @RequestMapping
and others that simplify the writing and configuration
of controllers
 InternalResourceViewResolver resolve the view
names, looks for JSPs that match a given view
name in the director /WEB-INF/jsp
 <context:component-scan...> tell Spring where to
automatically detect controllers

The ‘C’ in MVC
 DispatcherServlet delegates the request to the
controllers to execute the functionality specific to it
 The @Controller annotation indicates that a
particular class serves the role of a controller
 Controller interpret user input and transform this
input into specific model which will be represented to
the user by the view

The ‘M’ in MVC
 Model is generally defined as a MAP that can
contain objects that are to be displayed in view
 ModelAndView object encapsulates the relations
between view and model and is returned by
corresponding Controller methods
 ModelAndView class use ModelMap that is custom
MAP implementation where values are added in key-
value fashion

The ‘V’ in MVC
 View Page can be explicitly returned as part of
ModelAndView object by the controller
 In case of mapping logical name of view can be
resolved to particular view page in case
ModelAndView doesn’t contain the view reference
 The view name can be independent of view
technology (without using .jsp in controller) and
resolved to specific technology by using
ViewResolver and render by View

Defining a Controller
 @Controller annotation defines the class as a
Spring MVC controller
 @RequestMapping annotation is used to map a
URL to either an entire class or a particular handler
method
 DispatcherServlet delegates the request to the
controllers to execute the functionality specific to it

Defining a Controller cont…
@Controllerpublic
class HelloController{
@RequestMapping(value = "/hello", method = RequestMethod.GET)
public String printHello(ModelMap model) {
model.addAttribute("message", "Hello Spring MVC !");
return "hello";
}
}
 The value attribute indicates the URL to which the handler
method is mapped
 The method attribute defines the service method to handle
HTTP GET request

Creating JSP Views
 Spring MVC supports many types of views for different presentation
technologies. These include - JSPs, HTML, PDF, Excel worksheets, XML,
Velocity templates, XSLT, JSON, Atom and RSS feeds, JasperReports etc
 /WEB-INF/hello/hello.jsp:
<html>
<head>
<title>Hello Spring MVC</title>
</head>
<body>
<h2>${message}</h2>
</body>
</html>
 Here, ${message} is the attribute which we have setup inside the Controller

Spring vs. Struts
 Struts Framework
– Based on MVC architecture
– View – JSPs, ActionForms
– Controller – ActionServlet, Actions
 Spring Framework
– DispatcherServlet - Spring’s Front Controller implementation
– View- JSP’s
– ViewResolver - Maps logical View names to actual View
implementations
– HandlerMapping-Strategy interface used by DispatcherServlet for
mapping incoming requests to individual Controllers

Questions
Thank You
ravikant.soni@i-admin.com

Spring MVC 3.0 Framework

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