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1 02-Dec-2023 19:46 2 KB Juan Pablo custom wiki event listener docs - first version
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HowToWriteACustomWikiEventListener
HowToWriteACustomWikiEventListener

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[{TableOfContents title='How to write a custom wiki event listener'}]
See also:
* [JSPWikiPublicAPI]
* [DevelopmentEnvironment]
A custom wiki event listener is another JSPWiki extension point, in this case an specialization of a {{WikiEventListener}} that allows custom components be aware of all kind of events fired by JSPWiki. You may also be aware of these by registering a normal {{WikiEventListener}}, but custom wiki event listeners take care themselves of registering inside JSPWiki, which itself requires some deep knowledge of JSPWiki internals.
!! Code
Custom Wiki Event Listeners are implemented as {{[SPI|https://www.baeldung.com/java-spi]}}s.
Coding a custom wiki event listener is pretty straightforward, just needs two things:
* A {{CustomWikiEventListener}} class that implements the __{{org.apache.wiki.api.events.CustomWikiEventListener< T >}}__ interface. Implementations of the following methods are expected to be provided:
** {{void initialize( Engine engine, Properties props ) throws WikiException}}: to locate and store, the object firing the events you are interested in, so the listener can be attached to it later on.
** {{T client()}}: which returns the object located by the previous method, on which the {{CustomWikiEventListener}} will be registered.
** {{void actionPerformed( WikiEvent event )}}: in which the action related to the event is done.
* A {{META-INF/services/org.apache.wiki.api.events.CustomWikiEventListener}} file which contains the fully qualified class name of the {{CustomWikiEventListener}} implementation.
and that's it!
! What kinds of events are available?
There are lots of different types of events. The easiest way to see all them is by inspecting the {{org.apache.wiki.event.WikiEvent}} class and all of its subclasses. The {{actionPerformed}} method should take care of downcasting to the appropiate class, if needed, to the appropiate subtype(s) handled by the listener.
Also, each and every of these classes contain a handful of constants that act as event identifiers related to each kind of event, available at {{WikiEvent#getType()}}, so you may use this to discern the concrete event for a given {{WikiEvent}}subtype.
! Unit testing
See [JSPWikiPublicAPI#Testing]
!! Package
* Engine lifecycle extensions are usually bundled with another custom component. If it is needed to bundle the extension on a separate jar, see [StartingPointForCustomExtensions#Packaging]
!! Deploy
As engine lifecycle extensions are coded as {{[SPI|https://www.baeldung.com/java-spi]}}s, JSPWiki is automatically aware about the engine lifecycles extensions present, so there is no need of any further configuration.
[Category.Documentation]
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This page (revision-1) was last changed on 02-Dec-2023 19:46 by Juan Pablo  Top