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>
Note: It should be written in front of DispatcherServlet, and let defaultServlet intercept the request first, so that the request will not enter 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"
The name of the default Servlet that comes with Resin -- "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. How to use:
<!-- Access to static resource files--> <mvc:resources mapping="/images/**" location="/images/" />
Description: /images/** is mapped to ResourceHttpRequestHandler for processing, and 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 static resources to be web cached
Method three, use <mvc:default-servlet-handler/>
<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.
Supplementary note: Issues with the execution order of multiple HandlerMappings:
The order attribute value of DefaultAnnotationHandlerMapping is: 0
<mvc:resources/>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 order with a smaller 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 when accessing static resources in Scheme 2 and Scheme 3, if there is a matching (approximate) total interceptor, the interceptor will be used. 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.