[VELOCITY-439] Improve Resource existence detection

• Type: Improvement
• Status: Resolved
• Priority: Trivial
• Resolution: Fixed
• Affects Version/s: 1.4, 1.5
• Fix Version/s: 1.6
• Component/s: Engine
• Assignee: Unassigned
• Reporter: Tassos Bassoukos
• Created: 12/May/06 21:50
• Updated: 20/Aug/08 21:16
• Resolved: 20/Aug/08 21:16

Description

Depending on the ResourceLoader used, testing the existence of a resource is
somewhat expensive, as the resource has to be opened to test for its existence.

I'm proposing the following changes:
1.
Add a new method to org.apache.velocity.runtime.resource.loader.ResourceLoader:
public boolean resourceExists(String source) {
InputStream is = null;
try {
is = resourceLoader.getResourceStream(resourceName);
if (is != null)

{ return true; }

} catch (ResourceNotFoundException e) {
} finally {
if (is != null) {
try

{ is.close(); }

catch (Exception e) {
}
}
}
return false;
}

This method keeps compatibility with all current ResourceLoaders, and can be overriden by subclasses.

2. org.apache.velocity.runtime.resource.ResourceManagerImpl
Modify the String getLoaderNameForResource(String resourceName) method to use
the new ResourceLoader.resourceExists(String) method.