org.zkoss.zk.ui.util

Interface EventInterceptor

public interface EventInterceptor

The event interceptor used to intercept the processing of events.

To register an event interceptor to a desktop, invoke Desktop.addListener(java.lang.Object). To register an event intercepter to a configuration, invoke Configuration.addListener(java.lang.Class<?>).

Since:

3.0.0

Author:

tomyeh

Method Summary

Methods

Modifier and Type	Method and Description
void	afterProcessEvent(Event event) Called after processing an event.
Event	beforePostEvent(Event event) Called before posting an event (with Events.postEvent(org.zkoss.zk.ui.event.Event)).
Event	beforeProcessEvent(Event event) Called before processing an event.
Event	beforeSendEvent(Event event) Called before sending an event (with Events.sendEvent(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event)).

Method Detail

beforeSendEvent

Event beforeSendEvent(Event event)

Called before sending an event (with Events.sendEvent(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event)).

If this method throws an exception, it will abort the execution and shows an error message to the end user (unless it is cleaned up by EventThreadCleanup).

Parameters:

event - the event being sent

Returns:

the event to be sent (so it is usually the same event passed by the event argument). If null, the event is dropped. Note: multiple interceptors might be registered, and the returned value of an interceptor will be used for the following interceptor.

beforePostEvent

Event beforePostEvent(Event event)

Called before posting an event (with Events.postEvent(org.zkoss.zk.ui.event.Event)).

If this method throws an exception, it will abort the execution and shows an error message to the end user (unless it is cleaned up by EventThreadCleanup).

Parameters:

event - the event being posted

Returns:

the event to be posted (so it is usually the same event passed by the event argument). If null, the event is dropped. Note: multiple interceptors might be registered, and the returned value of an interceptor will be used for the following interceptor.

beforeProcessEvent

Event beforeProcessEvent(Event event)

Called before processing an event. By processing, we mean handing over the event to the event listeners and handlers.

Note: it executes in the event processing thread, so you can update the desktop whatever you need. For example, you might create a highlighted window and return null to prevent the user from accessing, if the system is too busy.

If this method throws an exception, it will abort the execution and shows an error message to the end user (unless it is cleaned up by EventThreadCleanup).

Parameters:

event - the event being processed

Returns:

the event to be processed (so it is usually the same event passed by the event argument). If null, the event is dropped. Note: multiple interceptors might be registered, and the returned value of an interceptor will be used for the following interceptor.

afterProcessEvent

void afterProcessEvent(Event event)

Called after processing an event. By processing, we mean handing over the event to the event listeners and handlers.

If this method throws an exception, it will abort the execution and shows an error message to the end user (unless it is cleaned up by EventThreadCleanup).

Parameters:

event - the event being processed