Hello everyone,
in our application (with wicket 1.4.5) we 're using a static
ResourceReferences and pass it into several Wicket Images
(setImageResourceReference) that are displayed in multiple rows of
several DataViews. At the first glanze everything works fine, but during
performancetests we ran occasionally into NullpointerExceptions in the
bind method of the Resource Reference. A deeper look into the wicket
source showed us, that the field "resource" of the ResourceReference has
to be 'null' (see ResourceReference line 141). As the field is checked
for not being 'null' just the line above this seems to be a
multithreading issue.
Actually we thought that ResourceReferences could be shared as statics
through the application. Is this assumption wrong?
Is there a standard mechanism to be used then instead?
Thanks for your help,
andy
_____________Details:
A deeper Look into wicket brought us to the following point:
The Image class is using a LocalizedImageResource. On calling
setImageResourceReference the LocalizedImageResource.bind Method is
called. In there, the resourceReference.bind is called and afterwards
(as the resource is a PackageReource) resource.setLocale. Set Locale is
invalidating the field 'resource' by setting it to 'null' and could be
the root cause of the NullpointerException thrown.
______________The ResourceReference Definition:
class ImageAnchor {
public static final IMAGE = new ResourceReference(ImageAnchor.class,
"image.gif");
}
_______________The Exception thrown:
Root cause: class java.lang.NullPointerException
java.lang.NullPointerException
at
org.apache.wicket.ResourceReference.bind(ResourceReference.java:141)
at
org.apache.wicket.markup.html.image.resource.LocalizedImageResource.bind(LocalizedImageResource.java:180)
at
org.apache.wicket.markup.html.image.resource.LocalizedImageResource.setResourceReference(LocalizedImageResource.java:246)
at
org.apache.wicket.markup.html.image.resource.LocalizedImageResource.setResourceReference(LocalizedImageResource.java:220)
at
org.apache.wicket.markup.html.image.Image.setImageResourceReference(Image.java:166)
[..]
at
org.apache.wicket.markup.repeater.RefreshingView$1.newItem(RefreshingView.java:114)
at
org.apache.wicket.markup.repeater.DefaultItemReuseStrategy$1.next(DefaultItemReuseStrategy.java:71)
at
org.apache.wicket.markup.repeater.DefaultItemReuseStrategy$1.next(DefaultItemReuseStrategy.java:68)
at
org.apache.wicket.markup.repeater.RefreshingView.addItems(RefreshingView.java:186)
at
org.apache.wicket.markup.repeater.RefreshingView.onPopulate(RefreshingView.java:98)
at
org.apache.wicket.markup.repeater.AbstractRepeater.onBeforeRender(AbstractRepeater.java:131)
at
org.apache.wicket.markup.repeater.AbstractPageableView.onBeforeRender(AbstractPageableView.java:116)
_________ ResourceReference.java:138-141:
if ((resource != null) && (resource instanceof PackageResource))
{
// see newResource() as well.
locale = ((PackageResource)resource).getLocale();
[..]
}
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please visit http://www.messagelabs.com/email
______________________________________________________________________
---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org
For additional commands, e-mail: users-h...@wicket.apache.org
