web,xml配置：
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
version="4.0">
<servlet>
<servlet-name>springmvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
或者修改自定义命名空间：
或者放在resource下：
springmvc-servlet.xml配置。
文件名字需要叫：xxx--servlet.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-4.3.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd">
<!-- 配置自定义扫描包 -->
<context:component-scan base-package="com.imooc.web"></context:component-scan>
<!-- 拦截器的注册 -->
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/user/**"/>
<bean class="com.imooc.core.LogInterceptor"></bean>
</mvc:interceptor>
<mvc:interceptor>
<!--<mvc:mapping path="/user/search"/>
<mvc:mapping path="/user/updatepwd"/>
<mvc:mapping path="/user/updateheaderPic"/>-->
<!--/user/* 只有一层路径-->
<!--<mvc:mapping path="/user/*"></mvc:mapping>-->
<!--/user/** 是路径以及子路径-->
<mvc:mapping path="/user/**"></mvc:mapping>
<!--exclude-mapping在所有拦截中进行排除，一般在通配符会有意义。-->
<mvc:exclude-mapping path="/user/updatepwd"></mvc:exclude-mapping>
<mvc:exclude-mapping path="/user/updatebackground/*"></mvc:exclude-mapping>
<bean class="com.imooc.core.LoginInterceptor"></bean>
</mvc:interceptor>
</mvc:interceptors>
<!-- 映射物理路径 -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/pages/"></property>
<property name="suffix" value=".jsp"></property>
</bean>
</beans>
拦截器配置多个时，是按顺序执行。afterCompletion是所有拦截器执行完毕后，再回头执行（倒序执行？）。
具体顺序如图：
