Summary of common processing methods for static files in javaweb

The examples in this article summarize the common processing methods of static files in javaweb, which are of great practical value in Javaweb program development. The specific methods are summarized as follows:

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

Add in web.xml:

<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>

Description: To be written in front of DispatcherServlet, let defaultServlet intercept the request first, so that the request will not Entering Spring, I think the performance is 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"
Resin comes with The name of the default Servlet -- "resin-file"
The name of the default Servlet that comes with WebLogic -- "FileServlet"
The name of the default Servlet that comes with WebSphere -- "SimpleFileServlet"

Method 2: mvc:resources is provided in spring 3.0.4 and later versions. Usage method:

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

## Description: /images/** is mapped to ResourceHttpRequestHandler for processing. Location specifies the location of the static resource. It can be in 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 make static resources web cache

Method 3, use

<mvc:default-servlet-handler/>

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 uses the default Servlet of each Servlet container.

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

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 have 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 like *.do, the above problems will not exist. It is still convenient to have a suffix.

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