DispatcherServlet的作用

1. 文件上传解析,如果请求类型是multipart,将通过MultipartResolver进行文件上传解析

2. 通过HandlerMapping将请求映射到处理器Controller上,（返回一个HandlerExecutionChain，它包括一个处理器、多个HandlerInterceptor拦截器）

3. 通过ViewResolver解析逻辑视图名到具体视图实现

4. 本地化解析

5. 渲染具体的视图等

6. 如果执行过程中遇到异常将交给HandlerExceptionResolver来解析。

   在web.xml里面的配置

   
   

7.     <servlet>
           <servlet-name>dispatcherServlet</servlet-name>
           <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
           <load-on-startup>1</load-on-startup>
       </servlet>
       <servlet-mapping>
           <servlet-name>dispatcherServlet</servlet-name>
           <url-pattern>/</url-pattern>
       </servlet-mapping>
       <!-- load-on-startup：表示启动容器时初始化该Servlet -->
       <!-- /可以拦截所有请求 -->

    针对7进行说明:

        web容器默认会在/WEB-INF/下面找dispatcherServlet-servler.xml没有找到会抛异常

严重: Servlet /spring02 threw load() exception
java.io.FileNotFoundException: Could not open ServletContext resource [/WEB-INF/dispatcherServlet-servlet.xml]
    at org.springframework.web.context.support.ServletContextResource.getInputStream(ServletContextResource.java:140)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:328)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:302)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:174)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:209)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:180)
    at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:125)
    at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:94)

修改路径

<servlet>
        <servlet-name>dispatcherServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring02-servlet.xml</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>dispatcherServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

web.xml中完整配置以及说明

<?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/javaee"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    id="WebApp_ID" version="3.0">

    <!-- get方式提交这里的CharacterEncodingFilter无法处理中文乱码情况 -->
    <!-- 这里的CharacterEncodingFilter只能处理post编码设置 -->
    <filter>
        <filter-name>characterEncodingFilter</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>characterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <servlet>
        <servlet-name>dispatcherServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring02-servlet.xml</param-value>
            <!-- 有关controller层的配置信息会放到spring02-servlet.xml里面去 -->
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>dispatcherServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    <!-- load-on-startup：表示启动容器时初始化该Servlet -->
    <!-- /可以拦截所有请求 -->

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:applicationContext.xml</param-value>
        <!-- 一般会将service层,dao层的配置放到applicationContext.xml里面去 -->
    </context-param>

</web-app>

看图说话