Eclipse
Eclipse
IDEA
IntelliJ
NetBeans
NetBeans
XpoLog
XpoLog
org.apache.tapestry.asset
Class AssetExternalizer
Tab mode
public class AssetExternalizer
Responsible for copying assets from the classpath to an external directory that is visible to the web server. The externalizer is stored inside the ServletContext as a named attribute.

The externalizer uses the name org.apache.tapestry.AssetExternalizer.application name . It configures itself using two additional properties (searching in getPropertySource() .

Parameter Description
org.apache.tapestry.asset.dir The directory to which assets will be copied.
org.apache.tapestry.asset.URL The corresponding URL for the asset directory.

If either of these parameters is null, then no externalization occurs. Private assets will still be available, just less efficiently, as the application will be invoked via its servlet and, ultimately, the AssetService will need to retrieve the asset.

Assets maintain thier directory structure when copied. For example, an asset with a resource path of /com/skunkworx/Banner.gif would be copied to the file system as dir/com/skunkworx/Banner.gif and would have a URL of URL/com/skunkworx/Banner.gif.

The externalizer will create any directories as needed.

The externalizer will not overwrite existing files. When a new version of the application is deployed with changed assets, there are two deployment stategies:

  • Delete the existing asset directory and allow the externalizer to recreate and repopulate it.
  • Change the asset directory and URL, allowing the old and new assets to exist side-by-side.

When using the second approach, it is best to use a directory that has a version number in it, for example, D:/inetpub/assets/0 mapped to the URL /assets/0. When a new version of the application is deployed, the trailing version number is incremented from 0 to 1.

SinceNot specified.
Version$Id: Asset
AuthorHoward Lewis Ship
Wiki javadoc Use textile entry format.
Add your comments here.
Constructor Summary
AssetExternalizer( IRequestCycle cycle )
No description provided.
Method Summary
protected void externalize( String resourcePath )
No description provided.
static AssetExternalizer get( IRequestCycle cycle )
Gets the externalizer singleton for the application.
String getURL( String resourcePath )
Gets the URL to a private resource.
Methods inherited from java.langObject
Constructor Detail
AssetExternalizer
protected AssetExternalizer ( IRequestCycle cycle )
No description provided.
Parameters
TypeNameDescription
IRequestCycle cycle No description provided.
Wiki javadoc Use textile entry format.
Add your comments here.
Method Detail
externalize
protected void externalize ( String resourcePath )
throws
No description provided.
Parameters
TypeNameDescription
String resourcePath No description provided.
Returns void No description provided.
Exceptions
IOException No description provided.
Wiki javadoc Use textile entry format.
Add your comments here.
get
public static AssetExternalizer get ( IRequestCycle cycle )
Gets the externalizer singleton for the application. If it does not already exist, it is created and stored into the ServletContext .

Each Tapestry application within a single ServletContext will have its own externalizer; they are differentiated by the application name.

Parameters
TypeNameDescription
IRequestCycle cycle No description provided.
See also
Wiki javadoc Use textile entry format.
Add your comments here.
getURL
public String getURL ( String resourcePath )
Gets the URL to a private resource. If the resource was previously copied out of the classpath, the previously generated URL is returned.

If the asset directory and URL are not configured, then returns null.

Otherwise, the asset is copied out to the asset directory, the URL is constructed (and recorded for later) and the URL is returned.

This method is not explicitly synchronized but should work multi-threaded. It synchronizes on the internal Map used to map resource paths to URLs.

Parameters
TypeNameDescription
String resourcePath The full path of the resource within the classpath. This is expected to include a leading slash. For example: /com/skunkworx/Banner.gif.
Wiki javadoc Use textile entry format.
Add your comments here.