Spring MVC2 and Apache Struts2

Spring and Apache MVC2

Spring
1. In application web.xml, define a 'servlet name' with a spring class and the URL pattern.  In the below example, the 'servlet name' is 'home'.    This is VERY important as spring looks for a ${servlet name}-servlet.xml in the same directory to set up the transfers between controller, modeler, and viewer.

<!DOCTYPE web-app PUBLIC

"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"

"http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>

<display-name>Spring MVC</display-name>

<servlet>

<servlet-name>home</servlet-name>

<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>

<load-on-startup>1</load-on-startup>

</servlet>

<servlet-mapping>

<servlet-name>home</servlet-name>

<url-pattern>/</url-pattern>

</servlet-mapping>

</web-app>

2. in home-servlet.xml, it tells spring that the MVC is annotation driven and the package name to scan for those MVC components.

<beans xmlns="http://www.springframework.org/schema/beans"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc"

xmlns:context="http://www.springframework.org/schema/context"

xsi:schemaLocation="http://www.springframework.org/schema/mvc

http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd

http://www.springframework.org/schema/beans

http://www.springframework.org/schema/beans/spring-beans-3.0.xsd

http://www.springframework.org/schema/context

http://www.springframework.org/schema/context/spring-context-3.0.xsd">

<!-- the following two lines tell Spring what to do with the Application code -->

<mvc:annotation-driven />

<context:component-scan base-package="com.urpattern.circleme.springmvc" />

<!-- tells Spring what's the Viewer's URL pattern such as .jsp suffix -->

<!-- <mvc:resources mapping="/resources/**" location="/resources/" /> -->

<bean

class="org.springframework.web.servlet.view.InternalResourceViewResolver">

<property name="viewClass"

value="org.springframework.web.servlet.view.JstlView" />

<property name="prefix">

<value>/views/</value>

</property>

<property name="suffix" value=".jsp" />

</bean>

</beans>

 Note the 'property' names and values given to the Spring '
InternalResourceViewResolver'

3. Component Annotation Scanning by Spring
The annotation tag @Controller tells Spring this is the application controller class. 

The annotation tag, @RequestMapping(/allhomes), tells Spring which URL, here '/allhomes', will be directed to this method of the controller, e.g. showAllHomes(Map<String, Object> model).  When transferring execution to this method, Spring also passes in a 'model'.  So the Controller prepares/calculates data and sets the return values in this 'model', then transfer execution to the Viewer (e.g. "home_list").   The viewer, home_list.jsp, will render the view of this 'model'.




The @autowire tells Spring to inject the instance of the class 'HomeService' into setHomeService() method.

@Controller

public class HomeController {

 ...

private HomeService homeService;

public HomeService getHomeService() {

return homeService;

}

@Autowired

public void setHomeService(HomeService homeService) {

this.homeService = homeService;

}

@RequestMapping("/allhomes")

public String showAllHomes(Map<String, Object> model) {

model.put("homes", getHomeService().fetchAllHomes());

return "home_list";

}

Deprecated Servlet in Struts2
org.springframework.web.servlet.DispatcherServlet

Missing Struts 1 Filter
java.lang.RuntimeException: java.lang.RuntimeException: com.opensymphony.xwork2.inject.DependencyException: com.opensymphony.xwork2.inject.ContainerImpl$MissingDependencyException: No mapping found for dependency [type=java.lang.String, name='actionPackages'] in public void org.apache.struts2.config.ClasspathPackageProvider.setActionPackages(java.lang.String).

at com.opensymphony.xwork2.inject.ContainerBuilder$4.create(ContainerBuilder.java:132)

From Codebehind to Convention Plugin

Changes required

• Replace org.apache.struts2.config.Namespace with org.apache.struts2.convention.annotation.Namespace
• Replace org.apache.struts2.config.Results with org.apache.struts2.convention.annotation.Results
• Replace org.apache.struts2.config.Result with org.apache.struts2.convention.annotation.Result
• Update @Result uses to use result name instead of Class<Result>
• Update @Result uses to use location instead of value attribute
• Update web.xml and remove Codebehind params from filter
• Update CamelCase action results and references to match Convention. For example:

  Previously in Codebehind: Given an action named AnExampleAction, a request to /anExample -> AnExampleAction.execute() -> > anExample-index.ftl Now in Convention: Given an action named AnExampleAction, a request to /an-example -> AnExampleAction.execute() -> an-example-index.ftl The pathname is relative to the application context path if it starts with "/" otherwise it is relative to the default results directory.  e.g. if the request is http://localhost:8080/FindMe/userinfo/getname and the result is directed to "fail.jsp", then the 'fail.jsp' should be at http://localhost:8080/FindMe/WEB-INF/pages/userinfo/fail.jsp. Here, the application context is 'http://localhost:8080/FindMe' and the results directory is http://localhost:8080/FindMe/WEB-INF/pages as defined in the struts.xml properties     <constant name="struts.convention.result.path" value="/WEB-INF/pages"/> All action, namespace, interceptor, and XWork package can be changed by annotations.

From import org.apache.struts2.config.ParentPackage; to import org.apache.struts2.convention.annotation.ParentPackage;