spring mvc 的设计模式

1. 使用spring，在web.xml中配置一个DispatcherServlet。

   <!--配置 spring 的DispatcherServlet--><servlet>        <servlet-name>SpringMVC</servlet-name>        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>        <init-param>            <param-name>contextConfigLocation</param-name>            <!--给出框架配置文件所在的路径-->            <param-value>classpath:conf/freemarker-servlet.xml</param-value>        </init-param></servlet><!--freemarker-servlet在conf/freemarker-servlet.xml文件中的参数配置如下--><!-- freemark -->     <bean id="freemarkerConfig"        class="org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer">        <property name="templateLoaderPath" value="/WEB-INF/ftl/" />        <property name="defaultEncoding" value="UTF-8" />    </bean>    <bean        class="org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver">        <property name="cache" value="true" />        <property name="prefix" value="" />        <property name="suffix" value=".ftl" />        <property name="exposeSpringMacroHelpers" value="true" />        <property name="exposeRequestAttributes" value="true" />        <property name="exposeSessionAttributes" value="true" />        <property name="requestContextAttribute" value="request" />        <property name="contentType" value="text/html; charset=utf-8" />    </bean><!--web.xml中的拦截会直接跳转到对应的方法， 我们并不关心--><servlet>        <servlet-name>authenticationServlet</servlet-name>    <servlet-class>        com.suning.ids.client.AuthenticationServlet    </servlet-class>    <load-on-startup>3</load-on-startup>    </servlet>    <servlet-mapping>        <!--所有连接中包含/auth的url-->        <!--都跳转到com.suning.ids.client.AuthenticationServlet-->        <servlet-name>authenticationServlet</servlet-name>        <url-pattern>/auth</url-pattern>    </servlet-mapping><!--只关心controller中request的方法-->

2.