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Detailed introduction to Spring MVC accessing static files

巴扎黑

Release： 2017-09-08 09:38:20

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This article mainly introduces the relevant information of Spring MVC to access static files in detail. It has certain reference value. Interested friends can refer to

How to intercept "*. For URLs with a suffix like "do", there is no problem of not being able to access static resources.

If your DispatcherServlet intercepts "/" and intercepts all requests in order to implement REST style, then access to static files such as *.js and *.jpg will also be intercepted.

We need to solve this problem.

Purpose: Static files can be accessed normally, and 404 cannot be reported when static files cannot be found.

Option 1: Activate Tomcat's defaultServlet to process static files

Xml code

<servlet-mapping>  
  <servlet-name>default</servlet-name> 
 <url-pattern>*.jpg</url-pattern>   
</servlet-mapping>  
<servlet-mapping>    
  <servlet-name>default</servlet-name>  
  <url-pattern>*.js</url-pattern>  
</servlet-mapping>  
<servlet-mapping>    
  <servlet-name>default</servlet-name>    
  <url-pattern>*.css</url-pattern>   
</servlet-mapping>

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To configure multiple, configure one for each file

To be written in front of DispatcherServlet, let defaultServlet intercept the request first, so that the request will not enter Spring, I want performance It's the best.

The name of the default Servlet that comes with Tomcat, Jetty, JBoss, and GlassFish -- "default"
The name of the default Servlet that comes with Google App Engine -- "_ah_default"
Comes with Resin The name of the default Servlet -- "resin-file"
WebLogic The name of the default Servlet that comes with it -- "FileServlet"
WebSphere The name of the default Servlet that comes with it -- "SimpleFileServlet"

Option 2: In spring3.0.4 and later versions, mvc:resources is provided. How to use:
Xml code

<!-- 对静态资源文件的访问 -->  
<mvc:resources mapping="/images/**" location="/images/" />

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/images /**Mapped to ResourceHttpRequestHandler for processing, location specifies the location of the static resource. It can be under the root directory of the web application or inside the jar package, so that the static resources can be compressed into the jar package. cache-period can enable web caching of static resources

If the following error occurs, it may be because is not configured.

Error WARNING: No mapping found for HTTP request with URI [/mvc/user/findUser/lisi/770] in DispatcherServlet with name 'springMVC'

Use

Another thing to note is that do not set defaultHandler for SimpleUrlHandlerMapping. Because the defaultHandler for static uri is ResourceHttpRequestHandler, otherwise static resources request cannot be processed.

Option 3: Use <mvc:default-servlet-handler/>Xml code

<mvc:default-servlet-handler/>

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The "/**" url will be registered in the urlMap of SimpleUrlHandlerMapping, and the access to static resources will be transferred from HandlerMapping to org.springframework.web.servlet.resource.DefaultServletHttpRequestHandler for processing and return. DefaultServletHttpRequestHandler is used Each Servlet container's own default Servlet.

Additional explanation: The execution order of multiple HandlerMapping issues:

The order attribute value of DefaultAnnotationHandlerMapping is: 0

The order attribute value of the automatically registered SimpleUrlHandlerMapping is: 2147483646

##<mvc:default-servlet-handler/> The order attribute value of the automatically registered SimpleUrlHandlerMapping is: 2147483647

Spring will execute the smaller order value first. When accessing an a.jpg image file, first find the processor through DefaultAnnotationHandlerMapping. It must not be found because we do not have an Action called a.jpg. Then search in ascending order of order value. Since the last SimpleUrlHandlerMapping matches "/**", it will definitely match and you can respond to the image.

To access an image, you need to go through layers of matching. Not sure how the performance is?

Finally, let me explain that Plan 2 and Plan 3 will use the interceptor if there is a matching (approximate) total interceptor when accessing static resources. If you implement permission checking in interception, be careful to filter these requests for static files.

If your DispatcherServlet intercepts URL suffixes such as *.do, the above problems will not exist. It is still convenient to have a suffix.

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