1.组合：事件集合

2.观察：onEvent驱动具体动作

public class ActiveInstallsInitializerListenerimplements EventListener

{

/**

* The events observed by this event listener.

*/

    private static final ListEVENTS =new ArrayList<>(Arrays.asList(new ApplicationReadyEvent()));

/**

* Used to send the ping to the remote instance.

    * <p>* Note that we use a Provider since the Observation Manager will register listeners very early in the

    * initialization process and some of the components injected transitively by the {@link InstanceIdManager}

* implementation have initialization code that require an Execution Context to be available, which is not the case

* early on in XWiki's initialization since no HTTP request has been made yet...

*/

    @Inject

    private ProviderpingSenderProvider;

/**

* Used to display the remote URL being hit in the logs if the ping fails...

*/

    @Inject

    private ActiveInstallsConfigurationconfiguration;

@Override

    public List getEvents()

{

return EVENTS;

}

@Override

    public String getName()

{

return "ActiveInstallsInitializerListener";

}

@Override

    public void onEvent(Event event, Object source, Object data)

{

// Start a thread to regularly send pings to the active installs server.

        Thread pingThread =new Thread(new ActiveInstallsPingThread(this.configuration,this.pingSenderProvider.get()));

pingThread.setName("Active Installs Ping Thread");

pingThread.start();

}

}