Life Cycle Listener
You could have some custom initialization and cleanup when an application, a session, a desktop or an execution is instantiated or about to be destroyed.
There are two steps:
- Implements the corresponding interface. For example, org.zkoss.zk.ui.util.WebAppInit for application’s initialization
- Register it in
WEB-INF/zk.xml, or in Java.
Interfaces
| Task | Interface |
|---|---|
| Application Init | org.zkoss.zk.ui.util.WebAppInit |
| Application Cleanup | org.zkoss.zk.ui.util.WebAppCleanup |
| Session Init | org.zkoss.zk.ui.util.SessionInit |
| Session Cleanup | org.zkoss.zk.ui.util.SessionCleanup |
| Desktop Init | org.zkoss.zk.ui.util.DesktopInit |
| Desktop Cleanup | org.zkoss.zk.ui.util.DesktopCleanup |
| Execution Init | org.zkoss.zk.ui.util.ExecutionInit |
| Execution Cleanup | org.zkoss.zk.ui.util.ExecutionCleanup |
Notice that ZK will instantiate an object from the class you registered for each callback. For example, an object is instantiated to invoke org.zkoss.zk.ui.util.DesktopInit#init(org.zkoss.zk.ui.Desktop, java.lnag.Object), and another object instantiated to invoke org.zkoss.zk.ui.util.DesktopCleanup#cleanup(org.zkoss.zk.ui.Desktop), even if you register a class that implements both org.zkoss.zk.ui.util.DesktopInit and org.zkoss.zk.ui.util.DesktopCleanup.
If you have something that is initialized in the init callback and have to clean it up in the cleanup callback, you cannot store it as a data member. Rather, you have to maintain it by yourself, such as storing it in the desktop’s attributes (org.zkoss.zk.ui.Desktop#setAttribute(java.lang.String, java.lang.Object)), session’s attributes or application’s attributes.
Registration
The registration in WEB-INF/zk.xml is the same, no matter what
interface you implement:
<listener>
<listener-class>my.MyImplementation</listener-class>
</listener>
The registration in Java is done by org.zkoss.zk.ui.util.Configuration#addListener(java.lang.Class).
webapp.getConfiguration().addListener(my.MyImplementation.class);