public class ResourceHttpRequestHandler extends WebContentGenerator implements HttpRequestHandler, InitializingBean
HttpRequestHandler that serves static resources optimized for superior browser performance
(according to the guidelines of Page Speed, YSlow, etc.) by allowing for flexible cache settings
("cacheSeconds" property, last-modified support).
The "locations" property takes a list of Spring Resource
locations from which static resources are allowed to be served by this handler. For a given request,
the list of locations will be consulted in order for the presence of the requested resource, and the
first found match will be written to the response, with Expires and Cache-Control
headers set as configured. The 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. The use of Resource locations
allows resource requests to easily be mapped to locations other than the web application root.
For example, resources could be served from a classpath location such as
"classpath:/META-INF/public-web-resources/", allowing convenient packaging and serving of resources
such as a JavaScript library from within jar files.
To ensure that users with a primed browser cache get the latest changes to application-specific resources upon deployment of new versions of the application, it is recommended that a version string is used in the URL mapping pattern that selects this handler. Such patterns can be easily parameterized using Spring EL. See the reference manual for further examples of this approach.
For various front-end needs — such as ensuring that users with a primed browser cache
get the latest changes, or serving variations of resources (e.g., minified versions) —
ResourceResolvers can be configured.
This handler can be configured through use of a
ResourceHandlerRegistry
or the <mvc:resources/> XML configuration element.
METHOD_GET, METHOD_HEAD, METHOD_POST| Constructor and Description |
|---|
ResourceHttpRequestHandler() |
| Modifier and Type | Method and Description |
|---|---|
void |
afterPropertiesSet()
Invoked by a BeanFactory after it has set all bean properties supplied
(and satisfied BeanFactoryAware and ApplicationContextAware).
|
List<Resource> |
getLocations() |
protected MediaType |
getMediaType(Resource resource)
Determine an appropriate media type for the given resource.
|
protected Resource |
getResource(HttpServletRequest request) |
List<ResourceResolver> |
getResourceResolvers()
Return the list of configured resource resolvers.
|
List<ResourceTransformer> |
getResourceTransformers()
Return the list of configured resource transformers.
|
void |
handleRequest(HttpServletRequest request,
HttpServletResponse response)
Processes a resource request.
|
protected void |
initAllowedLocations()
Look for a
PathResourceResolver
among the resource resolvers and configure
its "allowedLocations" to match the value of the
locations property unless the "allowed
locations" of the PathResourceResolver is non-empty. |
protected boolean |
isInvalidPath(String path)
Identifies invalid resource paths.
|
protected String |
processPath(String path)
Process the given resource path to be used.
|
protected void |
setHeaders(HttpServletResponse response,
Resource resource,
MediaType mediaType)
Set headers on the given servlet response.
|
void |
setLocations(List<Resource> locations)
Set a
List of Resource paths to use as sources
for serving static resources. |
void |
setResourceResolvers(List<ResourceResolver> resourceResolvers)
Configure the list of
ResourceResolvers to use. |
void |
setResourceTransformers(List<ResourceTransformer> resourceTransformers)
Configure the list of
ResourceTransformers to use. |
String |
toString() |
protected void |
writeContent(HttpServletResponse response,
Resource resource)
Write the actual content out to the given servlet response,
streaming the resource's content.
|
applyCacheSeconds, applyCacheSeconds, cacheForSeconds, cacheForSeconds, checkAndPrepare, checkAndPrepare, getCacheSeconds, getSupportedMethods, isAlwaysMustRevalidate, isRequireSession, isUseCacheControlHeader, isUseCacheControlNoStore, isUseExpiresHeader, preventCaching, setAlwaysMustRevalidate, setCacheSeconds, setRequireSession, setSupportedMethods, setUseCacheControlHeader, setUseCacheControlNoStore, setUseExpiresHeadergetServletContext, getTempDir, getWebApplicationContext, initApplicationContext, initServletContext, isContextRequired, setServletContextgetApplicationContext, getMessageSourceAccessor, initApplicationContext, requiredContextClass, setApplicationContextpublic void setLocations(List<Resource> locations)
List of Resource paths to use as sources
for serving static resources.public void setResourceResolvers(List<ResourceResolver> resourceResolvers)
ResourceResolvers to use.
By default PathResourceResolver is configured. If using this property,
it is recommended to add PathResourceResolver as the last resolver.
public List<ResourceResolver> getResourceResolvers()
public void setResourceTransformers(List<ResourceTransformer> resourceTransformers)
ResourceTransformers to use.
By default no transformers are configured for use.
public List<ResourceTransformer> getResourceTransformers()
public void afterPropertiesSet()
throws Exception
InitializingBeanThis method allows the bean instance to perform initialization only possible when all bean properties have been set and to throw an exception in the event of misconfiguration.
afterPropertiesSet in interface InitializingBeanException - in the event of misconfiguration (such
as failure to set an essential property) or if initialization fails.protected void initAllowedLocations()
PathResourceResolver
among the resource resolvers and configure
its "allowedLocations" to match the value of the
locations property unless the "allowed
locations" of the PathResourceResolver is non-empty.public void handleRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
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.
handleRequest in interface HttpRequestHandlerrequest - current HTTP requestresponse - current HTTP responseServletException - in case of general errorsIOException - in case of I/O errorsprotected Resource getResource(HttpServletRequest request) throws IOException
IOExceptionprotected String processPath(String path)
The default implementation replaces any combination of leading '/' and
control characters (00-1F and 7F) with a single "/" or "". For example
" // /// //// foo/bar" becomes "/foo/bar".
protected boolean isInvalidPath(String path)
StringUtils.cleanPath(java.lang.String).
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.
path - the path to validatetrue if the path is invalid, false otherwiseprotected MediaType getMediaType(Resource resource)
resource - the resource to checknull if none foundprotected void setHeaders(HttpServletResponse response, Resource resource, MediaType mediaType) throws IOException
response - current servlet responseresource - the identified resource (never null)mediaType - the resource's media type (never null)IOException - in case of errors while setting the headersprotected void writeContent(HttpServletResponse response, Resource resource) throws IOException
response - current servlet responseresource - the identified resource (never null)IOException - in case of errors while writing the content