You implement a model listener with a hook. Hooks and model listeners are described in the wiki post I linked to. Also, take a look at the SevenCogs hook that comes with your Liferay bundle to get a more handson grip on how hooks are used.
One thing has changed since Ray wrote the wiki post:
Now you don't register your model listener in the liferay-hook.xml file. You rather specify your model listener in a portal.properties file, and then register the portal.properties file in the liferay-hook.xml file.
1. To register a model listener - create a portal.properties file in your hook and specify your listener:
value.object.listener.com.liferay.portlet.documentlibrary.model.DLFileEntry=my.package.hook.listeners.DLFileEntryListener
2. Add your portal.properties to your liferay-hook.xml file:
<hook>
<portal-properties>portal.properties</portal-properties>
</hook>
3. Add your new listener class to your hook:
package my.package.hook.listeners;
import com.liferay.portal.ModelListenerException;
import com.liferay.portal.model.BaseModelListener;
import com.liferay.portlet.documentlibrary.model.DLFileEntry;
public class DLFileEntryListener extends BaseModelListener<group> {
public void onAfterCreate(DLFileEntry entry) throws ModelListenerException {
// The code you wish to be executed when a new entry has been made
System.out.println("A new document library entry was created");
}
}</group>
Hooks can be tricky to get at first. But play around with them for a while. Learning how they work unveils a lot of possibilities in Liferay.
Cheers,
Erik
