Module jakarta.faces

Package com.sun.faces.application.resource

Class ResourceHelper

java.lang.Object

com.sun.faces.application.resource.ResourceHelper

Direct Known Subclasses:

ClasspathResourceHelper, FaceletWebappResourceHelper, WebappResourceHelper

public abstract class ResourceHelper
extends Object

Implementations of this class contain the knowledge for finding and serving web application resources.

Since:

2.0

Constructor Summary

Constructors

Constructor	Description
ResourceHelper()

Method Summary

Modifier and Type	Method	Description
protected boolean	clientAcceptsCompression(FacesContext ctx)	This method attempt to verify that the user agent can accept a gzip encoded response by interrogating the Accept-Encoding requester header.
protected boolean	compressContent(ClientResourceInfo info)	Utility method to compress the content of the original resource to the temporary directory specified by ClientResourceInfo.getCompressedPath().
abstract LibraryInfo	findLibrary(String libraryName, String localePrefix, String contract, FacesContext ctx)	Search for the specified library/localPrefix combination in an implementation dependent manner.
abstract ResourceInfo	findResource(LibraryInfo library, String resourceName, String localePrefix, boolean compressable, FacesContext ctx)	Search for the specified resource based in the library/localePrefix/resourceName combination in an implementation dependent manner.
abstract String	getBaseContractsPath()
protected String	getBasePath(String contract)
abstract String	getBaseResourcePath()
InputStream	getInputStream(ResourceInfo toStream, FacesContext ctx)	If the resource is compressable, return an InputStream to read the compressed content, otherwise, call getNonCompressedInputStream(ResourceInfo, jakarta.faces.context.FacesContext) to return the content of the original resource.
long	getLastModified(ResourceInfo resource, FacesContext ctx)	The default implementation of this method will call through to getURL(ResourceInfo, jakarta.faces.context.FacesContext) and leverage the URL to obtain the date information of the resource and return the value of URLConnection.getLastModified()
protected List<String>	getLocalizedPaths(String path, FacesContext ctx)
protected abstract InputStream	getNonCompressedInputStream(ResourceInfo info, FacesContext ctx)	If a ResourceInfo is not compressable, getInputStream(ResourceInfo, jakarta.faces.context.FacesContext) will call this method to return a stream to the actual resource.
abstract URL	getURL(ResourceInfo resource, FacesContext ctx)
protected VersionInfo	getVersion(Collection<String> resourcePaths, boolean isResource)	Given a collection of path names:
protected ClientResourceInfo	handleCompression(ClientResourceInfo resource)	Utility method to peform the necessary actions to compress content.
protected boolean	resourceSupportsEL(String resourceName, String libraryName, FacesContext ctx)
protected String	trimLeadingSlash(String s)

Methods inherited from class java.lang.Object

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

Constructor Details

ResourceHelper

public ResourceHelper()

Method Details

getBaseResourcePath

public abstract String getBaseResourcePath()

Returns:

the base path in which resources will be stored

getBaseContractsPath

public abstract String getBaseContractsPath()

getBasePath

protected String getBasePath(String contract)

getInputStream

public InputStream getInputStream(ResourceInfo toStream,
 FacesContext ctx)
                           throws IOException

If the resource is compressable, return an InputStream to read the compressed content, otherwise, call getNonCompressedInputStream(ResourceInfo, jakarta.faces.context.FacesContext) to return the content of the original resource.

Implementation Note: If any exception occurs trying to return a stream to the compressed content, log the exception, and instead try to return a stream to the original content.

Parameters:

toStream - the resource to obtain an InputStream to

ctx - the FacesContext for the current request

Returns:

an InputStream to the resource, or null if no resource is found

Throws:

IOException - if an error occurs obtaining the stream

getURL

public abstract URL getURL(ResourceInfo resource,
 FacesContext ctx)

Parameters:

resource - the resource to obtain a URL reference to

ctx - the FacesContext for the current request

Returns:

a URL to the specified resource, otherwise null if no resource is found

findLibrary

public abstract LibraryInfo findLibrary(String libraryName,
 String localePrefix,
 String contract,
 FacesContext ctx)

Search for the specified library/localPrefix combination in an implementation dependent manner.

Parameters:

libraryName - the name of the library

localePrefix - the logicial identifier for a locale specific library. if no localePrefix is configured, pass null

contract - the name of the contract

ctx - the FacesContext for the current request @return a LibraryInfo if a matching library based off the inputs can be found, otherwise returns null

Returns:

library info

findResource

public abstract ResourceInfo findResource(LibraryInfo library,
 String resourceName,
 String localePrefix,
 boolean compressable,
 FacesContext ctx)

Search for the specified resource based in the library/localePrefix/resourceName combination in an implementation dependent manner.

If the resource is found, and is compressable, call handleCompression(com.sun.faces.application.resource.ClientResourceInfo) to compress the content.

Parameters:

library - the library this resource should be a part of. If the the resource that is being searched for isn't part of a library, then pass null

resourceName - the name of the resource that is being searched for

localePrefix - the logicial identifier for a locale specific library. if no localePrefix is configured, pass null

compressable - true if the resource can be compressed

ctx - the FacesContext for the current request

Returns:

a ResourceInfo if a matching resource based off the inputs can be found, otherwise returns null

getLastModified

public long getLastModified(ResourceInfo resource,
 FacesContext ctx)

The default implementation of this method will call through to getURL(ResourceInfo, jakarta.faces.context.FacesContext) and leverage the URL to obtain the date information of the resource and return the value of URLConnection.getLastModified()

Parameters:

resource - the resource in question

ctx - the FacesContext for the current request

Returns:

the date of the resource in milliseconds (since epoch), or 0 if the date cannot be determined

getNonCompressedInputStream

protected abstract InputStream getNonCompressedInputStream(ResourceInfo info,
 FacesContext ctx)
                                                    throws IOException

If a ResourceInfo is not compressable, getInputStream(ResourceInfo, jakarta.faces.context.FacesContext) will call this method to return a stream to the actual resource.

Parameters:

info - the resource to obtain an InputStream to

ctx - the FacesContext for the current request

Returns:

an InputStream to the resource

Throws:

IOException - if an error occurs obtaining the stream

getVersion

protected VersionInfo getVersion(Collection<String> resourcePaths,
 boolean isResource)

Given a collection of path names:

   1.1, scripts, images, 1.2
 

this method will pick out the directories that represent a library or resource version and return the latest version found, if any.

Parameters:

resourcePaths - a collection of paths (consisting of single path elements)

isResource - true if the version being looked up is for a reource, otherwise, pass false if the version is a library version

Returns:

the latest version or if no version can be detected, otherwise this method returns null

compressContent

protected boolean compressContent(ClientResourceInfo info)
                           throws IOException

Utility method to compress the content of the original resource to the temporary directory specified by ClientResourceInfo.getCompressedPath().

Parameters:

info - the resource to be compressed

Returns:

true if compression succeeded and the compressed result is smaller than the original content, otherwise false

Throws:

IOException - if any error occur reading/writing

clientAcceptsCompression

protected boolean clientAcceptsCompression(FacesContext ctx)

This method attempt to verify that the user agent can accept a gzip encoded response by interrogating the Accept-Encoding requester header. If it is determined safe to send a gzip encoded response, send the Content-Encoding header with a value of gzip.

See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html RFC 2616, sec. 14 for details on the accept-encoding header.

Implementation Note: It is safe to cast to a HttpServletResponse as this method will only be called when handling a resource request. Resource serving is outside of the Faces and Portlet lifecycle.

Parameters:

ctx - the FacesContext for the current request

Returns:

true if compressed content can be sent to the client, otherwise false

handleCompression

protected ClientResourceInfo handleCompression(ClientResourceInfo resource)

Utility method to peform the necessary actions to compress content.

Implmentation Note: If an exception occurs while compressing the content, log the IOException and rebuilt the ResourceInfo as non-compressable.

Parameters:

resource - the resource to compression

Returns:

the ResourceInfo after compression is complete. If compression was successful, this should be the same instance. If compression was not successful, it will be a different instance than what was passed.

resourceSupportsEL

protected boolean resourceSupportsEL(String resourceName,
 String libraryName,
 FacesContext ctx)

trimLeadingSlash

protected String trimLeadingSlash(String s)

Parameters:

s - input String

Returns:

the String without a leading slash if it has one.

getLocalizedPaths

protected List<String> getLocalizedPaths(String path,
 FacesContext ctx)