Model-View-Controller(MVC) is a software pattern for user interfaces. It encourages clean design by separating out the three components of the Graphical User Interface (GUI) into three components – Model,
View and Controller
It consists of 3 components –
- Controller – This is normally Front Controller, which delegates to specific controls
- Model – The controller updates the model
- View – The controller then decides which view to return
The flow is sometimes easier to see in a sequence diagram –
Configuration
Front Controller – web.xml
This is the starting point for configuration –
<display-name>parkrunPB</display-name>
<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>
Here the DispatcherServlet is the Front Controller
Spring Configuration – spring-servlet.xml
This configuration is using the default name for the spring configuration file which matches the servlet name with a -servlet.xml appended – spring-servlet.xml
The key areas of this configuration are –
<context:component-scan base-package="com.glenware.parkrunpb" />
<context:annotation-config />
<mvc:annotation-driven/>
<bean id="jspViewResolver"
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="viewClass" value="org.springframework.web.servlet.view.JstlView" />
<property name="prefix" value="/WEB-INF/jsp/" />
<property name="suffix" value=".jsp" />
</bean>
<bean id="messageSource"
class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
<property name="basename" value="classpath:messages" />
<property name="defaultEncoding" value="UTF-8" />
</bean>
In spring terms we’re basically –
- Setting up annotation driven configuration on package com.glenware.parkrunpb
- ViewResolver – check /WEB-INF/jsp for files ending in .jsp
- Messages – check classpath for messages.properties
AboutController – Simple Example
The simplest controller in parkrunPB is the AboutController –
@Controller
public class AboutController {
@RequestMapping("/about")
public String about() {
return "about";
}
}
The key attributes of this controller are –
- @Controller – Marks the class as a Controller
- @RequestMapping(“/about”) – Method is called when /parkrunPB/about is called
- return “about” – This is where the view resolver kicks in an searches for the corresponding view – /WEB-INF/jsp/about.jsp
References
Images courtesy of (any issues and they will be removed/replaced) –
http://docs.spring.io/spring-framework/docs/3.0.x/reference/mvc.html
http://java4developers.com/2011/spring-mvc-basic-example-with-maven/
http://www.theserverside.com/news/1364355/Ajax-and-the-Spring-Framework-with-TIBCO-General-Interface
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