javax.enterprise.inject.spi.ObserverMethod Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package javax.enterprise.inject.spi;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.util.Set;
import javax.enterprise.event.Reception;
import javax.enterprise.event.TransactionPhase;
/**
* ObserverMethod is the SPI to handle an observer method, which is
* an event consumer for an event of the given type T. An instance of
* ObserverMethod exists for every observer method of every enabled bean.
*
* A class may have n observer methods.
* Each observer method must have a void return value and exactly one parameter
* which defines which event it {@code javax.enterprise.event.Observes}.
* The observed event may be further specified by using an optional Qualifier.
*
* Sample:
*
* public class UserHandler
* {
* public void afterUserLogin(@Observes UserLoginEvent userHasLoggedIn)
* {
* // prepare some data for the user, ...
* int userId = userHadLoggedIn.getUserId();
* ...
* }
*
* public void afterAdminLogin(@Observes @Admin UserLoginEvent userHasLoggedIn)
* {
* // prepare stuff for the admin user
* ...
* }
*
* public void afterUserLogout(@Observes UserLogoutEvent userHasLoggedOut)
* {
* // cleanup afterwards
* ...
* }
* }
*
*
* @param the event which should be observed
* @see javax.enterprise.event.Observes
*/
public interface ObserverMethod extends Prioritized
{
/**
* The default Priority of any ObserverMethod without a @Priority annotation.
*/
int DEFAULT_PRIORITY = 2500;
Class getBeanClass();
/**
* @return the type of the observed event
*/
Type getObservedType();
/**
* @return the defined Qualifiers plus {@code javax.enterprise.inject.Any}
*/
Set getObservedQualifiers();
/**
* @return either {@code Reception#IF_EXISTS} if the observed method must only be called if an instance
* of the bean which defines the observer method aready exists in the specified context or {@code Reception#ALWAYS}.
*/
Reception getReception();
/**
* @return the appropriate {@code TransactionPhase} for a transactional observer method or
* {@code TransactionPhase#IN_PROGRESS} otherwise.
*/
TransactionPhase getTransactionPhase();
/**
* will actually call the underlying observer method
* @param event
*/
default void notify(T event)
{
// empty by default
}
/**
* Call the observer method with the given eventContext.
* @param eventContext
*/
default void notify(EventContext eventContext)
{
if (eventContext != null)
{
notify(eventContext.getEvent());
}
}
/**
* @return Whether or not this observer method is an async observer. defaults to false for compatibility
*/
default boolean isAsync()
{
return false;
}
/**
* Only synchronous ObserverMethods can be ordered!
*
* @return The @Priority of this ObserverMethod
*/
default int getPriority()
{
return DEFAULT_PRIORITY;
}
}