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Spring Framework example source code file (SourceFilteringListener.java)

This example Spring Framework source code file (SourceFilteringListener.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

applicationlistener, applicationlistener, illegalstateexception, must, must, object, object, sourcefilteringlistener, sourcefilteringlistener

The Spring Framework SourceFilteringListener.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 org.springframework.context.ApplicationEvent;
import org.springframework.context.ApplicationListener;

/**
 * {@link org.springframework.context.ApplicationListener} decorator that filters
 * events from a specified event source, invoking its delegate listener for
 * matching {@link org.springframework.context.ApplicationEvent} objects only.
 *
 * <p>Can also be used as base class, overriding the {@link #onApplicationEventInternal}
 * method instead of specifying a delegate listener.
 *
 * @author Juergen Hoeller
 * @since 2.0.5
 */
public class SourceFilteringListener implements ApplicationListener {

	private final Object source;

	private ApplicationListener delegate;


	/**
	 * Create a SourceFilteringListener for the given event source.
	 * @param source the event source that this listener filters for,
	 * only processing events from this source
	 * @param delegate the delegate listener to invoke with event
	 * from the specified source
	 */
	public SourceFilteringListener(Object source, ApplicationListener delegate) {
		this.source = source;
		this.delegate = delegate;
	}

	/**
	 * Create a SourceFilteringListener for the given event source,
	 * expecting subclasses to override the {@link #onApplicationEventInternal}
	 * method (instead of specifying a delegate listener).
	 * @param source the event source that this listener filters for,
	 * only processing events from this source
	 */
	protected SourceFilteringListener(Object source) {
		this.source = source;
	}


	public void onApplicationEvent(ApplicationEvent event) {
		if (event.getSource() == this.source) {
			onApplicationEventInternal(event);
		}
	}

	/**
	 * Actually process the event, after having filtered according to the
	 * desired event source already.
	 * <p>The default implementation invokes the specified delegate, if any.
	 * @param event the event to process (matching the specified source)
	 */
	protected void onApplicationEventInternal(ApplicationEvent event) {
		if (this.delegate == null) {
			throw new IllegalStateException(
					"Must specify a delegate object or override the onApplicationEventInternal method");
		}
		this.delegate.onApplicationEvent(event);
	}

}

Other Spring Framework examples (source code examples)

Here is a short list of links related to this Spring Framework SourceFilteringListener.java source code file:

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