org.springframework.context.event

Class SimpleApplicationEventMulticaster

java.lang.Object

org.springframework.context.event.AbstractApplicationEventMulticaster

org.springframework.context.event.SimpleApplicationEventMulticaster

All Implemented Interfaces:

Aware, BeanClassLoaderAware, BeanFactoryAware, ApplicationEventMulticaster

public class SimpleApplicationEventMulticaster
extends AbstractApplicationEventMulticaster

Simple implementation of the ApplicationEventMulticaster interface.

Multicasts all events to all registered listeners, leaving it up to the listeners to ignore events that they are not interested in. Listeners will usually perform corresponding instanceof checks on the passed-in event object.

By default, all listeners are invoked in the calling thread. This allows the danger of a rogue listener blocking the entire application, but adds minimal overhead. Specify an alternative task executor to have listeners executed in different threads, for example from a thread pool.

Author:

Rod Johnson, Juergen Hoeller, Stephane Nicoll

See Also:

setTaskExecutor(java.util.concurrent.Executor)

Field Summary

Fields

Modifier and Type	Field and Description
private ErrorHandler	errorHandler
private java.util.concurrent.Executor	taskExecutor

Constructor Summary

Constructors

Constructor and Description
SimpleApplicationEventMulticaster() Create a new SimpleApplicationEventMulticaster.
SimpleApplicationEventMulticaster(BeanFactory beanFactory) Create a new SimpleApplicationEventMulticaster for the given BeanFactory.

Method Summary

Modifier and Type	Method and Description
protected ErrorHandler	getErrorHandler() Return the current error handler for this multicaster.
protected java.util.concurrent.Executor	getTaskExecutor() Return the current task executor for this multicaster.
protected void	invokeListener(ApplicationListener listener, ApplicationEvent event) Invoke the given listener with the given event.
void	multicastEvent(ApplicationEvent event) Multicast the given application event to appropriate listeners.
void	multicastEvent(ApplicationEvent event, ResolvableType eventType) Multicast the given application event to appropriate listeners.
private ResolvableType	resolveDefaultEventType(ApplicationEvent event)
void	setErrorHandler(ErrorHandler errorHandler) Set the ErrorHandler to invoke in case an exception is thrown from a listener.
void	setTaskExecutor(java.util.concurrent.Executor taskExecutor) Set a custom executor (typically a TaskExecutor) to invoke each listener with.

Methods inherited from class org.springframework.context.event.AbstractApplicationEventMulticaster

addApplicationListener, addApplicationListenerBean, getApplicationListeners, getApplicationListeners, removeAllListeners, removeApplicationListener, removeApplicationListenerBean, setBeanClassLoader, setBeanFactory, supportsEvent, supportsEvent

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

taskExecutor

private java.util.concurrent.Executor taskExecutor

errorHandler

private ErrorHandler errorHandler

Constructor Detail

SimpleApplicationEventMulticaster

public SimpleApplicationEventMulticaster()

Create a new SimpleApplicationEventMulticaster.

SimpleApplicationEventMulticaster

public SimpleApplicationEventMulticaster(BeanFactory beanFactory)

Create a new SimpleApplicationEventMulticaster for the given BeanFactory.

Method Detail

setTaskExecutor

public void setTaskExecutor(java.util.concurrent.Executor taskExecutor)

Set a custom executor (typically a TaskExecutor) to invoke each listener with.

Default is equivalent to SyncTaskExecutor, executing all listeners synchronously in the calling thread.

Consider specifying an asynchronous task executor here to not block the caller until all listeners have been executed. However, note that asynchronous execution will not participate in the caller's thread context (class loader, transaction association) unless the TaskExecutor explicitly supports this.

See Also:

SyncTaskExecutor, SimpleAsyncTaskExecutor

getTaskExecutor

protected java.util.concurrent.Executor getTaskExecutor()

Return the current task executor for this multicaster.

setErrorHandler

public void setErrorHandler(ErrorHandler errorHandler)

Set the ErrorHandler to invoke in case an exception is thrown from a listener.

Default is none, with a listener exception stopping the current multicast and getting propagated to the publisher of the current event. If a task executor is specified, each individual listener exception will get propagated to the executor but won't necessarily stop execution of other listeners.

Consider setting an ErrorHandler implementation that catches and logs exceptions (a la TaskUtils.LOG_AND_SUPPRESS_ERROR_HANDLER) or an implementation that logs exceptions while nevertheless propagating them (e.g. TaskUtils.LOG_AND_PROPAGATE_ERROR_HANDLER).

Since:

4.1

getErrorHandler

protected ErrorHandler getErrorHandler()

Return the current error handler for this multicaster.

Since:

4.1

multicastEvent

public void multicastEvent(ApplicationEvent event)

Description copied from interface: ApplicationEventMulticaster

Multicast the given application event to appropriate listeners.

Consider using ApplicationEventMulticaster.multicastEvent(ApplicationEvent, ResolvableType) if possible as it provides a better support for generics-based events.

Parameters:

event - the event to multicast

multicastEvent

public void multicastEvent(ApplicationEvent event,
                           ResolvableType eventType)

Description copied from interface: ApplicationEventMulticaster

Multicast the given application event to appropriate listeners.

If the eventType is null, a default type is built based on the event instance.

Parameters:

event - the event to multicast

eventType - the type of event (can be null)

resolveDefaultEventType

private ResolvableType resolveDefaultEventType(ApplicationEvent event)

invokeListener

protected void invokeListener(ApplicationListener listener,
                              ApplicationEvent event)

Invoke the given listener with the given event.

Parameters:

listener - the ApplicationListener to invoke

event - the current event to propagate

Since:

4.1