Spring之MVC模块

Spring MVC的Controller用于处理用户的请求。Controller相当于Struts 1里的Action，他们的实现机制、运行原理都类似

Controller是个接口，一般直接继承AbstrcatController，并实现handleRequestInternal方法。handleRequestInternal方法相当于Struts 1的execute方法

import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.AbstractController;

public class CatController extends AbstractController{
      private ICatService catService;
      //setter、getter略

      protected ModelAndView handleRequestInternal(HttpServletRequestrequest,HttpServletResponse response) throws Exception{
             String action =request.getParameter("action");
             if("list".equals(action)){
                    return this.list(request,response);
             }
      }

      protected ModelAndView list(HttpServletRequestrequest,HttpServletResponse response) throws Exception{
             List<Cat> catList =catService.listCat();
             request.setAttribute("catList", catList);
             return new ModelAndView("cat/listCat");
      }

}

Spring MVC没有内置数据的封装，开发者可以自己封装数据转换代码

Spring MVC独特的地方在于view层的处理上。handleRequestInternal返回ModelAndView对象，可以看做是对JSP对象的封装。ModelAndIView直接接受JSP页面的路径。例如参数＂cat/listCat＂，只是JSP路径的一部分，实际完整的路径是＂WEB-INF/jsp/cat/catList.jsp＂，路径前后的部分是配置在配置文件中的

除了制定JSP路径，ModelAndView还可以直接传递Model对象到View层，而不用事先放到request中，例如new ModelAndView(＂cat/listCat＂,＂cat＂,cat)，如果传递多个参数，可以使用Map，如

Map map = newHashMap();
map.put("cat",cat);
map.put("catList",catList);
return new ModelAndView("cat/listCat",map);

一般使用一个独立的xml文件如spring-action.xml专门配置web相关的组件

<?xml version= "1.0" encoding="UTF-8"?>
<!DCTYPEbeans PUBLIC "-//SPRING//DTD BEAN//EN"
  "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
      <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
             <property name="prefix">
                    <value>/WEB-INF/jsp/</value><!--  JSP前缀-->
             </property>
             <property name="suffix">
                    <value>.jsp</value>                 <!--  JSP后缀-->
             </property>

      <!-- 配置URL Mapping-->
      <bean id="urlHandlerMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandleMapping">
             <property name="mappings">
                    <props><!—Controller的URL会被配置成"cat.mvc"-->
                           <prop key="cat.mvc">catController</prop>
                    <props>
             </property>
      </bean>
      <bean id="catController" class="com.clf.spring.CatController">
             <property name="catService" ref="catService"></property>
      </bean>
</beans>

web.xml配置
<context-param><!--  Spring配置文件的位置-->
      <param-name>contextConfigLocation</param-name>
      <param-value>
             /WEB-INF/classes/applicationContext.xml,
             /WEB-INF/classes/spring-action.xml
      </param-value>
</context-param>

<listener><!--  使用Listener加载Spring配置文件-->
      <listener-class>
             org.springframework.web.context.ContextLoaderListener
      </listener-class>
</listener>

<servlet><!--  spring分发器-->
      <servlet-name>spring</servlet-name>
      <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
      <init-param>
             <param-name>contextConfigLocation</param-name>
             <param-value>/WEB-INF/classes/spring-action.xml</param-value>
      </init-param>
      <load-on-startup>1</load-on-startup><!--  启动时加载-->
</servlet>

<servlet-mapping>
      <servlet-name> spring</servlet-name>
      <url>*.mvc</url>
</servlet-mapping>

如果一个Controller要处理多个业务逻辑，可以使用MultiActionController，相当于Struts 1中的DispatchAction，能根据某个参数将不同的请求分发到不同的方法上

import org.springframework.web.servlet.mvc.multiaction.MultiActionController;

public class CatController extends AbstractController{
      private ICatService catService;
      //setter、getter略

      protected ModelAndView add(HttpServletRequestrequest,HttpServletResponse response) throws Exception{
             ……
             return new ModelAndView(＂cat/addCat＂);
      }

      protected ModelAndView list(HttpServletRequestrequest,HttpServletResponse response) throws Exception{
             List<Cat> catList =catService.listCat();
             request.setAttribute(＂catList＂, catList);
             return new ModelAndView(＂cat/listCat＂);
      }

}

配置到spring-action.xml

<bean id="paraMethodResolver" class="org.springframework.web.servlet.mvc.multiaction.ParameterMethodNameResolver">
      <property name="paramName">
             <value>action</value><!--  配置分发参数-->
      </property>
      <property name="defaultMethodName">
             <value>list</value><!--  配置默认的执行方法-->
      </property>
</bean>

<bean id="urlHandlerMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandleMapping">
             <property name="mappings">
                    <props>
                           <prop key="cat.mvc">catController</prop><!--  访问"cat.mvc"则交给catController处理-->
                           <prop key="catMulti.mvc">catMultiController</prop><!--  访问"catMulti.mvc"则交给catMultiController处理-->
                    <props>
             </property>
      </bean>

      <bean id="catController" class="com.clf.spring.CatMultiController">
             <property name="catService" ref="catService"></property>
      </bean>

      <bean id="catMultiController" class="com.clf.spring.CatController">
             <property name="catService" ref="catService"></property>
      </bean>