The main purpose is to record my own doubts, and I generally don't ask for trouble like me.

When using SpringMVC, we need to configure the front controller DispatcherServlet with web.xml

web.xml

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Archetype Created Web Application</display-name>

  <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:springmvc.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  
  <servlet-mapping>
    <servlet-name>DispatcherServlet</servlet-name>
    <url-pattern>*.action</url-pattern>
  </servlet-mapping>

</web-app>

What does DispatcherServlet do?

In 拦截请求（浏览器的访问），然后根据自己定义的规则，去匹配处理器（Controller）来处理short, .

Then specifically what requests to intercept

url-pattern configures this.

It has three configurations

Absolute path/UserServlet
Multi-level directory /aaa/bbb/UserServlet
Wildcard matches *.action *.do (as long as the request is followed by .action or .do, the servlet will be executed)

There are two special ones (better not to write)

<url-pattern >/< /url-pattern>
is a /, if written in this way, DispatcherServlet will 静态资源obtain requests from, such as .css, .js, .jpg, .png and other resources 当作一个普通的Controller请求。中央调度器会调用处理器映射器为其查找相应的处理器. This is not found, it will report 404.
<URL-pattern> / * </ URL-pattern>
* represents all, i.e. 静态资源, 动态页面（jsp页面，servlet）other requests are intercepted. 把静态资源、jsp页面的获取请求当作Controller请求去找处理器, Then can't find and then 404.

If you insist on writing /, it can be solved.

You need to use the <mvc:resources/> tag in the springmvc configuration file to solve the problem of inaccessibility of static resources
Insert picture description here
. The login.html and qqq.jpg in the picture are not accessible at this time.
We just write the following code in the springmvc.xml file.

<mvc:resources location="/page/" mapping="/page/**"/>

locationIndicates all directories of static resources, here can also be the /WEB-INF/ directory and its subdirectories.
mappingIndicates a request for this resource. Two stars* behind.

This configuration will directly map the request for access to the static resource to the static resource handler object ResourceHttpRequestHandler via HandlerMapping.

About DispatcherServlet's url-pattern configuration (/* or /)