1. 搭建springmvc(spring)框架 (ss整合) 4.1. 引入相关的jar(忽略)
      4.2. 在web.xml中配置核心入口(servlet)
    1. <servlet>
    2.   <servlet-name>mvc</servlet-name>
    3.   <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    4.   <init-param>
    5.     <param-name>contextConfigLocation</param-name>
    6.     <param-value>classpath:mvc.xml</param-value>
    7.   </init-param>
    8. </servlet>
    9. <servlet-mapping>
    10.   <servlet-name>mvc</servlet-name>
    11.   <url-pattern>/</url-pattern>
    12. </servlet-mapping>