Spring Framework example source code file (SimpleApplicationEventMulticaster.java)

This example Spring Framework source code file (SimpleApplicationEventMulticaster.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Spring Framework tags/keywords

abstractapplicationeventmulticaster, applicationevent, applicationevent, applicationlistener, applicationlistener, iterator, runnable, simpleapplicationeventmulticaster, synctaskexecutor, synctaskexecutor, taskexecutor, taskexecutor, util

The Spring Framework SimpleApplicationEventMulticaster.java source code

/*
 * Copyright 2002-2007 the original author or authors.
 *
 * Licensed 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 org.springframework.context.event;

import java.util.Iterator;

import org.springframework.context.ApplicationEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.core.task.SyncTaskExecutor;
import org.springframework.core.task.TaskExecutor;

/**
 * Simple implementation of the {@link ApplicationEventMulticaster} interface.
 *
 * <p>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 <code>instanceof
 * checks on the passed-in event object.
 *
 * <p>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 TaskExecutor to have
 * listeners executed in different threads, for example from a thread pool.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @see #setTaskExecutor
 * @see #setConcurrentUpdates
 */
public class SimpleApplicationEventMulticaster extends AbstractApplicationEventMulticaster {

	private TaskExecutor taskExecutor = new SyncTaskExecutor();


	/**
	 * Set the TaskExecutor to execute application listeners with.
	 * <p>Default is a SyncTaskExecutor, executing the listeners synchronously
	 * in the calling thread.
	 * <p>Consider specifying an asynchronous TaskExecutor 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 org.springframework.core.task.SyncTaskExecutor
	 * @see org.springframework.core.task.SimpleAsyncTaskExecutor
	 * @see org.springframework.scheduling.timer.TimerTaskExecutor
	 */
	public void setTaskExecutor(TaskExecutor taskExecutor) {
		this.taskExecutor = (taskExecutor != null ? taskExecutor : new SyncTaskExecutor());
	}

	/**
	 * Return the current TaskExecutor for this multicaster.
	 */
	protected TaskExecutor getTaskExecutor() {
		return this.taskExecutor;
	}


	public void multicastEvent(final ApplicationEvent event) {
		for (Iterator it = getApplicationListeners().iterator(); it.hasNext();) {
			final ApplicationListener listener = (ApplicationListener) it.next();
			getTaskExecutor().execute(new Runnable() {
				public void run() {
					listener.onApplicationEvent(event);
				}
			});
		}
	}

}