org.springframework.web.servlet.resource

Class AppCacheManifestTransformer

java.lang.Object

org.springframework.web.servlet.resource.ResourceTransformerSupport

org.springframework.web.servlet.resource.AppCacheManifestTransformer

All Implemented Interfaces:

ResourceTransformer

public class AppCacheManifestTransformer
extends ResourceTransformerSupport

A ResourceTransformer implementation that helps handling resources within HTML5 AppCache manifests for HTML5 offline applications.

This transformer:

• modifies links to match the public URL paths that should be exposed to clients, using configured ResourceResolver strategies
• appends a comment in the manifest, containing a Hash (e.g. "# Hash: 9de0f09ed7caf84e885f1f0f11c7e326"), thus changing the content of the manifest in order to trigger an appcache reload in the browser.

All files that have the ".appcache" file extension, or the extension given in the constructor, will be transformed by this class. This hash is computed using the content of the appcache manifest and the content of the linked resources; so changing a resource linked in the manifest or the manifest itself should invalidate the browser cache.

In order to serve manifest files with the proper "text/manifest" content type, it is required to configure it with contentNegotiationConfigurer.mediaType("appcache", MediaType.valueOf("text/manifest") in a WebMvcConfigurer.

Since:

4.1

Author:

Brian Clozel

See Also:

HTML5 offline applications spec

Constructor Summary

Constructors

Constructor and Description
AppCacheManifestTransformer() Create an AppCacheResourceTransformer that transforms files with extension ".appcache".
AppCacheManifestTransformer(java.lang.String fileExtension) Create an AppCacheResourceTransformer that transforms files with the extension given as a parameter.

Method Summary

Modifier and Type	Method and Description
Resource	transform(HttpServletRequest request, Resource resource, ResourceTransformerChain chain) Transform the given resource.

Methods inherited from class org.springframework.web.servlet.resource.ResourceTransformerSupport

getResourceUrlProvider, resolveUrlPath, setResourceUrlProvider, toAbsolutePath

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AppCacheManifestTransformer

public AppCacheManifestTransformer()

Create an AppCacheResourceTransformer that transforms files with extension ".appcache".

AppCacheManifestTransformer

public AppCacheManifestTransformer(java.lang.String fileExtension)

Create an AppCacheResourceTransformer that transforms files with the extension given as a parameter.

Method Detail

transform

public Resource transform(HttpServletRequest request,
                          Resource resource,
                          ResourceTransformerChain chain)
                   throws java.io.IOException

Description copied from interface: ResourceTransformer

Transform the given resource.

Parameters:

request - the current request

resource - the resource to transform

chain - the chain of remaining transformers to delegate to

Returns:

the transformed resource (never null)

Throws:

java.io.IOException - if the transformation fails