web.xml中 /和/*的区别

< url-pattern>/</url-pattern>  会匹配到/login这样的路径型url，不会匹配到模式为*.jsp这样的后缀型url
< url-pattern>/*</url-pattern> 会匹配所有url：路径型的和后缀型的url(包括/login,*.jsp,*.js和*.html等)

因为 springmvc 要使用DispatcherServlet类 处理 前端的 请求，所以配置为< url-pattern > / </ url-pattern >    将路径型url  交给springMVC处理

例如  中文乱码处理、shiro 安全认证处理需要处理所有的 url ，所以配置为< url-pattern > /* </ url-pattern >

< url-pattern > / </ url-pattern >   不会匹配到*.jsp，即：*.jsp不会进入spring的 DispatcherServlet类 。
< url-pattern > /* </ url-pattern >  会匹配*.jsp，会出现返回jsp视图时再次进入spring的DispatcherServlet 类，导致找不到对应的controller所以报404错。

例某 web.xml文件配置：

 <?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">
    <!-- 配置spring   上下文参数 -->
   <context-param>
     <param-name>contextConfigLocation</param-name>
     <param-value>classpath:applicationContext.xml</param-value>
   </context-param>
    <!-- 配置spring ---- 配置侦听器 -->
   <listener>
     <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
   </listener>
   <!-- 配置springmvc  核心控制器 -->
   <servlet>
     <servlet-name>springDispatcherServlet</servlet-name>
     <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
     <init-param>
       <param-name>contextConfigLocation</param-name>
       <param-value>classpath:springMVC.xml</param-value>
     </init-param>
     <load-on-startup>1</load-on-startup>
   </servlet>
   <servlet-mapping>
     <servlet-name>springDispatcherServlet</servlet-name>
     <url-pattern>/</url-pattern>
   </servlet-mapping>
   <!-- 配置shiro认证过滤器 -->
   <filter>
     <filter-name>shiroFilter</filter-name>
     <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
     <init-param>
       <param-name>targetFilterLifecycle</param-name>
       <param-value>true</param-value>
     </init-param>
   </filter>
   <filter-mapping>
     <filter-name>shiroFilter</filter-name>
     <url-pattern>/*</url-pattern>
   </filter-mapping>
   <!-- 配置编码过滤器（只对post方法） -->
   <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>
     <init-param>
       <param-name>forceRequestEncoding</param-name>
       <param-value>true</param-value>
     </init-param>
     <init-param>
       <param-name>forceResponseEncoding</param-name>
       <param-value>true</param-value>
     </init-param>
   </filter>
   <filter-mapping>
     <filter-name>CharacterEncodingFilter</filter-name>
     <url-pattern>/*</url-pattern>
   </filter-mapping>
 </web-app>