Spring MVC------->version4.3.6-------->第一个Spring MVC程序

step1，配置DispatcherServlet

• • web.xml中配置DispatcherServlet，使其拦截相应的请求

    <servlet>
            <servlet-name>dispatcher</servlet-name>
            <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
            <init-param>
                <param-name>contextConfigLocation</param-name>
                <param-value></param-value>
            </init-param>
            <load-on-startup>1</load-on-startup>
       </servlet>
       <servlet-mapping>
            <servlet-name>dispatcher</servlet-name>
            <url-pattern>*.do</url-pattern>
       </servlet-mapping>

    如上配置，使得DispatcherServlet实例dispatcher可以拦截所有以.do结尾的请求

step2，编写DispatcherServlet对应的WebApplicationContext,也即[servlet-name]-servlet.xml.

• • step1中servlet-name设置为dispatcher,所以该DispatcherServlet实例对应的WebApplicationContext就是dispatcher-servlet.xml　
  • [servlet-name]-servlet.xml中管理哪些beans?

step3,编写其他ApplicationContext（即IOC容器），实际上也就是spring对应的各个xml形式的配置文件，里面定义了各种beans

• • 如 /WEB-INF/spring-services.xml里面定义了各种业务逻辑组件bean
  • 再如 /WEB-INF/spring-dao.xml里面定义了各种数据持久化组件bean　　

step4,在web.xml中配置一个上下文载入器，使得step2中所说的对应于DispatcherServlet实例的WebApplicationContext能够被自动加载，得到拥有其定义的所有beans的IOC容器

• • web.xml　

    <servlet>
               <servlet-name>context</servlet-name>
               <servlet-class>org.springframework.web.context.ContextLoaderServlet</servlet-class>
               <load-on-startup>2</load-on-startup>
    </servlet>

step4，还需要在web.xml中指定配置文件的位置，只有这样，step4中的上下文加载器才能知道该到哪里去加载相应的ApplicationContext实例

• • web.xml

    <context-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>
                /WEB-INF/root-context.xml,
                /WEB-INF/dispatcher-servlet.xml,　　　　     /WEB-INF/spring-services.xml,           /WEB-INF/spring-dao.xml
            </param-value>
      </context-param>

阶段性小结：step1-step4所形成的的web.xml文件

• • <?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:javaee="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" version="2.4">
    
      <display-name>Archetype Created Web Application</display-name>
    
      <!-- 定义ApplicationContext文件的位置 -->
      <context-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>
                /WEB-INF/root-context.xml,
                /WEB-INF/dispatcher-servlet.xml,
                /WEB-INF/spring-services.xml,
                /WEB-INF/spring-dao.xml
            </param-value>
      </context-param>
    
      <!-- 定义DispatcherServlet对象，并且配置servlet-mapping，使得DispatcherServlet对象能够拦截相应的请求 -->
      <servlet>
            <servlet-name>dispatcher</servlet-name>
            <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
            <!--
            <init-param>
                <param-name>contextConfigLocation</param-name>
                <param-value>
                    /WEB-INF/dispatcher-servlet.xml
                </param-value>
            </init-param>
            -->
            <load-on-startup>1</load-on-startup>
       </servlet>
       <servlet-mapping>
            <servlet-name>dispatcher</servlet-name>
            <url-pattern>*.do</url-pattern>
       </servlet-mapping>
    
       <!-- 在web.xml中指定一个上下文加载器，使得DispatcherServlet对应的WebApplicationContext
                   (也即[servlet-name]-servlet.xml)能够被自动加载
             也使得 普通类型的spring ApplicationContext能够被自动加载-->
       <servlet>
               <servlet-name>context</servlet-name>
               <servlet-class>org.springframework.web.context.ContextLoaderServlet</servlet-class>
               <load-on-startup>2</load-on-startup>
       </servlet>
    
    </web-app>