org.springframework.web.reactive.resource

Class ResourceWebHandler

java.lang.Object

org.springframework.web.reactive.resource.ResourceWebHandler

All Implemented Interfaces:

InitializingBean, WebHandler

public class ResourceWebHandler
extends Object
implements WebHandler, InitializingBean

HttpRequestHandler that serves static resources in an optimized way according to the guidelines of Page Speed, YSlow, etc.

The "locations" property takes a list of Spring Resource locations from which static resources are allowed to be served by this handler. Resources could be served from a classpath location, e.g. "classpath:/META-INF/public-web-resources/", allowing convenient packaging and serving of resources such as .js, .css, and others in jar files.

This request handler may also be configured with a resourcesResolver and resourceTransformer chains to support arbitrary resolution and transformation of resources being served. By default a PathResourceResolver simply finds resources based on the configured "locations". An application can configure additional resolvers and transformers such as the VersionResourceResolver which can resolve and prepare URLs for resources with a version in the URL.

This handler also properly evaluates the Last-Modified header (if present) so that a 304 status code will be returned as appropriate, avoiding unnecessary overhead for resources that are already cached by the client.

Since:

5.0

Author:

Rossen Stoyanchev, Brian Clozel, Juergen Hoeller

Constructor Summary

Constructors

Constructor and Description
ResourceWebHandler()

Method Summary

Modifier and Type	Method and Description
void	afterPropertiesSet() Invoked by the containing BeanFactory after it has set all bean properties and satisfied BeanFactoryAware, ApplicationContextAware etc.
CacheControl	getCacheControl() Return the CacheControl instance to build the Cache-Control HTTP response header.
List<Resource>	getLocations() Return the List of Resource paths to use as sources for serving static resources.
List<String>	getLocationValues() Return the configured location values.
Map<String,MediaType>	getMediaTypes() Return the configured media type mappings.
protected reactor.core.publisher.Mono<Resource>	getResource(ServerWebExchange exchange)
ResourceHttpMessageWriter	getResourceHttpMessageWriter() Return the configured resource message writer.
List<ResourceResolver>	getResourceResolvers() Return the list of configured resource resolvers.
List<ResourceTransformer>	getResourceTransformers() Return the list of configured resource transformers.
reactor.core.publisher.Mono<Void>	handle(ServerWebExchange exchange) Processes a resource request.
protected void	initAllowedLocations() Look for a PathResourceResolver among the configured resource resolvers and set its allowedLocations property (if empty) to match the locations configured on this class.
protected boolean	isInvalidPath(String path) Identifies invalid resource paths.
boolean	isOptimizeLocations() Return whether to optimize the specified locations through an existence check on startup, filtering non-existing directories upfront so that they do not have to be checked on every resource access.
boolean	isUseLastModified() Return whether the Resource.lastModified() information is used to drive HTTP responses when serving static resources.
protected String	processPath(String path) Process the given resource path.
void	setCacheControl(CacheControl cacheControl) Set the CacheControl instance to build the Cache-Control HTTP response header.
protected void	setHeaders(ServerWebExchange exchange, Resource resource, MediaType mediaType) Set headers on the response.
void	setLocations(List<Resource> locations) Set the List of Resource paths to use as sources for serving static resources.
void	setLocationValues(List<String> locationValues) Accepts a list of String-based location values to be resolved into Resource locations.
void	setMediaTypes(Map<String,MediaType> mediaTypes) Add mappings between file extensions extracted from the filename of static Resources and the media types to use for the response.
void	setOptimizeLocations(boolean optimizeLocations) Set whether to optimize the specified locations through an existence check on startup, filtering non-existing directories upfront so that they do not have to be checked on every resource access.
void	setResourceHttpMessageWriter(ResourceHttpMessageWriter httpMessageWriter) Configure the ResourceHttpMessageWriter to use.
void	setResourceLoader(ResourceLoader resourceLoader) Provide the ResourceLoader to load location values with.
void	setResourceResolvers(List<ResourceResolver> resourceResolvers) Configure the list of ResourceResolvers to use.
void	setResourceTransformers(List<ResourceTransformer> resourceTransformers) Configure the list of ResourceTransformers to use.
void	setUseLastModified(boolean useLastModified) Set whether we should look at the Resource.lastModified() when serving resources and use this information to drive "Last-Modified" HTTP response headers.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

ResourceWebHandler

public ResourceWebHandler()

Method Detail

setResourceLoader

public void setResourceLoader(ResourceLoader resourceLoader)

Provide the ResourceLoader to load location values with.

Since:

5.1

setLocationValues

public void setLocationValues(List<String> locationValues)

Accepts a list of String-based location values to be resolved into Resource locations.

Since:

5.1

getLocationValues

public List<String> getLocationValues()

Return the configured location values.

Since:

5.1

setLocations

public void setLocations(@Nullable
                         List<Resource> locations)

Set the List of Resource paths to use as sources for serving static resources.

getLocations

public List<Resource> getLocations()

Return the List of Resource paths to use as sources for serving static resources.

Note that if locationValues are provided, instead of loaded Resource-based locations, this method will return empty until after initialization via afterPropertiesSet().

Note: As of 5.3.11 the list of locations may be filtered to exclude those that don't actually exist and therefore the list returned from this method may be a subset of all given locations. See setOptimizeLocations(boolean).

See Also:

setLocationValues(java.util.List<java.lang.String>), setLocations(java.util.List<org.springframework.core.io.Resource>)

setResourceResolvers

public void setResourceResolvers(@Nullable
                                 List<ResourceResolver> resourceResolvers)

Configure the list of ResourceResolvers to use.

By default PathResourceResolver is configured. If using this property, it is recommended to add PathResourceResolver as the last resolver.

getResourceResolvers

public List<ResourceResolver> getResourceResolvers()

Return the list of configured resource resolvers.

setResourceTransformers

public void setResourceTransformers(@Nullable
                                    List<ResourceTransformer> resourceTransformers)

Configure the list of ResourceTransformers to use.

By default no transformers are configured for use.

getResourceTransformers

public List<ResourceTransformer> getResourceTransformers()

Return the list of configured resource transformers.

setResourceHttpMessageWriter

public void setResourceHttpMessageWriter(@Nullable
                                         ResourceHttpMessageWriter httpMessageWriter)

Configure the ResourceHttpMessageWriter to use.

By default a ResourceHttpMessageWriter will be configured.

getResourceHttpMessageWriter

@Nullable
public ResourceHttpMessageWriter getResourceHttpMessageWriter()

Return the configured resource message writer.

setCacheControl

public void setCacheControl(@Nullable
                            CacheControl cacheControl)

Set the CacheControl instance to build the Cache-Control HTTP response header.

getCacheControl

@Nullable
public CacheControl getCacheControl()

Return the CacheControl instance to build the Cache-Control HTTP response header.

setUseLastModified

public void setUseLastModified(boolean useLastModified)

Set whether we should look at the Resource.lastModified() when serving resources and use this information to drive "Last-Modified" HTTP response headers.

This option is enabled by default and should be turned off if the metadata of the static files should be ignored.

Since:

5.3

isUseLastModified

public boolean isUseLastModified()

Return whether the Resource.lastModified() information is used to drive HTTP responses when serving static resources.

Since:

5.3

setOptimizeLocations

public void setOptimizeLocations(boolean optimizeLocations)

Set whether to optimize the specified locations through an existence check on startup, filtering non-existing directories upfront so that they do not have to be checked on every resource access.

The default is false, for defensiveness against zip files without directory entries which are unable to expose the existence of a directory upfront. Switch this flag to true for optimized access in case of a consistent jar layout with directory entries.

Since:

5.3.13

isOptimizeLocations

public boolean isOptimizeLocations()

Return whether to optimize the specified locations through an existence check on startup, filtering non-existing directories upfront so that they do not have to be checked on every resource access.

Since:

5.3.13

setMediaTypes

public void setMediaTypes(Map<String,MediaType> mediaTypes)

Add mappings between file extensions extracted from the filename of static Resources and the media types to use for the response.

Use of this method is typically not necessary since mappings can be also determined via MediaTypeFactory.getMediaType(Resource).

Parameters:

mediaTypes - media type mappings

Since:

5.3.2

getMediaTypes

public Map<String,MediaType> getMediaTypes()

Return the configured media type mappings.

Since:

5.3.2

afterPropertiesSet

public void afterPropertiesSet()
                        throws Exception

Description copied from interface: InitializingBean

Invoked by the containing BeanFactory after it has set all bean properties and satisfied BeanFactoryAware, ApplicationContextAware etc.

This method allows the bean instance to perform validation of its overall configuration and final initialization when all bean properties have been set.

Specified by:

afterPropertiesSet in interface InitializingBean

Throws:

Exception - in the event of misconfiguration (such as failure to set an essential property) or if initialization fails for any other reason

initAllowedLocations

protected void initAllowedLocations()

Look for a PathResourceResolver among the configured resource resolvers and set its allowedLocations property (if empty) to match the locations configured on this class.

handle

public reactor.core.publisher.Mono<Void> handle(ServerWebExchange exchange)

Processes a resource request.

Checks for the existence of the requested resource in the configured list of locations. If the resource does not exist, a 404 response will be returned to the client. If the resource exists, the request will be checked for the presence of the Last-Modified header, and its value will be compared against the last-modified timestamp of the given resource, returning a 304 status code if the Last-Modified value is greater. If the resource is newer than the Last-Modified value, or the header is not present, the content resource of the resource will be written to the response with caching headers set to expire one year in the future.

Specified by:

handle in interface WebHandler

Parameters:

exchange - the current server exchange

Returns:

Mono<Void> to indicate when request handling is complete

getResource

protected reactor.core.publisher.Mono<Resource> getResource(ServerWebExchange exchange)

processPath

protected String processPath(String path)

Process the given resource path.

The default implementation replaces:

• Backslash with forward slash.
• Duplicate occurrences of slash with a single slash.
• Any combination of leading slash and control characters (00-1F and 7F) with a single "/" or "". For example " / // foo/bar" becomes "/foo/bar".

Since:

3.2.12

isInvalidPath

protected boolean isInvalidPath(String path)

Identifies invalid resource paths. By default rejects:

• Paths that contain "WEB-INF" or "META-INF"
• Paths that contain "../" after a call to StringUtils.cleanPath(java.lang.String).
• Paths that represent a valid URL or would represent one after the leading slash is removed.

Note: this method assumes that leading, duplicate '/' or control characters (e.g. white space) have been trimmed so that the path starts predictably with a single '/' or does not have one.

Parameters:

path - the path to validate

Returns:

true if the path is invalid, false otherwise

setHeaders

protected void setHeaders(ServerWebExchange exchange,
                          Resource resource,
                          @Nullable
                          MediaType mediaType)
                   throws IOException

Set headers on the response. Called for both GET and HEAD requests.

Parameters:

exchange - current exchange

resource - the identified resource (never null)

mediaType - the resource's media type (never null)

Throws:

IOException

toString

public String toString()

Overrides:

toString in class Object