SpringMVC 静态资源缓存

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ResourceHttpRequestHandler

ResourceHttpRequestHandler 可以使用 ResourceResolvers 和 ResourceTransformers 来优化处理静态资源。处理过程如下：

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Request for Resource
     |
     | HTTP request
     v
 Resolvers chain: FirstResolver, SecondResolver, ThirdResolver
 (each resolver can return the resource or delegate to the next one)
     |
     | Resolved Resource
     v
 Transformers chain: FirstTransformer, SecondTransformer
 (each transformer can transform the resource or just pass it along without modification)
     |
     | Transformed Resource
     v
 HTTP Response with Resource content

ResourceHttpRequestHandler 的配置

配置方法一：

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@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {
  @Override
  public void addResourceHandlers(ResourceHandlerRegistry registry) {
    registry.addResourceHandler("/resources/**")
            .addResourceLocations("/public-resources/")
            .setCacheControl(CacheControl.maxAge(1, TimeUnit.HOURS).cachePublic());
  }

}

配置方法二：

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<mvc:resources mapping="/resources/**" location="/public-resources/">
  <mvc:cache-control max-age="3600" cache-public="true"/>
</mvc:resources>

ResourceResolvers

用于解析资源，将外面请求的 public 路径解析为内部的资源路径。

处理过程

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Resource link in a template source file
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| Resource path (like “/css/main.css”)
v
Resolvers chain: FirstResolver, SecondResolver, ThirdResolver
(each resolver can modify the resource path or delegate to the next one)
|
| Updated resource path (like “/css/main-0e37f12.css”)
v
Resource link in a rendered template

配置

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<mvc:resources mapping="/resources/**" location="/public/">
  <mvc:resource-chain>
    <mvc:resource-cache/>
    <mvc:resolvers>
      <mvc:version-resolver>
        <mvc:content-version-strategy patterns="/**"/>
      </mvc:version-resolver>
    </mvc:resolvers>
  </mvc:resource-chain>
</mvc:resources>

实现类

实现类 作用
PathResourceResolver finds resources under configured locations (classpath, file system…) matching to the request path
CachingResourceResolver resolves resources from a Cache instance or delegates to the next Resolver in the chain
GzipResourceResolver finds variations of a resource with a “.gz” extension when HTTP clients support gzip compression
VersionResourceResolver resolves request paths containing a version string, i.e. version information about the resource being requested. This resolver can be useful to set up HTTP caching strategies by changing resources’ URLs as they are updated.

ResourceTransformers

用于修改资源内容。

实现类

实现类 作用
CssLinkResourceTransformer modifies links in a CSS file to match the public URL paths that should be exposed to clients
CachingResourceTransformer caches the result of transformations in a Cache or delegates to the next Transformer in the chain
AppCacheManifestTransfomer helps handling resources within HTML5 AppCache manifests for HTML5 offline applications

静态资源添加 Hash

1 添加 filter

修改 web.xml:

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<!-- 静态资源 URL 添加 Hash -->
<filter>
  <filter-name>resourceUrlEncodingFilter</filter-name>
  <filter-class>org.springframework.web.servlet.resource.ResourceUrlEncodingFilter</filter-class>
</filter>
<!-- Ensure that you map it to the DispatcherServlet -->
<filter-mapping>
  <filter-name>resourceUrlEncodingFilter</filter-name>
  <servlet-name>webServlet</servlet-name>
  <!--<url-pattern>/*</url-pattern>-->
</filter-mapping>

2 添加 resolver

修改 SpringMVC 的配置文件：

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<mvc:resources mapping="/static/**" location="/static/" cache-period="31536000">
  <mvc:resource-chain resource-cache="true" auto-registration="true">
    <mvc:resolvers>
      <mvc:version-resolver>
        <mvc:content-version-strategy patterns="/**"/>
        <!-- <mvc:fixed-version-strategy version="1.1.1" patterns="/**"/> -->
      </mvc:version-resolver>
    </mvc:resolvers>
  </mvc:resource-chain>
</mvc:resources>

3 修改 view

修改相应的 JSP：

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<!-- css -->
<link rel="stylesheet" href="<c:url value="/static/vendors/bootstrap/css/bootstrap.min.css"/>">

<!-- javascript -->
<script src="<c:url value="/static/vendors/bootstrap/js/bootstrap.min.js"/>"></script>

参考

  1. handling static web resources
  2. Spring Web MVC
  3. Cachable Static Assets with Spring MVC
  4. Preventing caching of static resources in Spring MVC legacy projects using XML config