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);               returnnew 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＂?>  <!DCTYPE beansPUBLIC ＂-//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>