scheduledexecutorfactorybean.java

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/*
 * Copyright 2002-2006 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.scheduling.concurrent;

import java.util.concurrent.Executors;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.util.Assert;

/**
 * {@link FactoryBean} that sets up a JDK 1.5 {@link ScheduledExecutorService}
 * (by default: {@link ScheduledThreadPoolExecutor} as implementation)
 * and exposes it for bean references.
 *
 * <p>Allows for registration of {@link ScheduledExecutorTask ScheduledExecutorTasks},
 * automatically starting the {@link ScheduledExecutorService} on initialization and
 * cancelling it on destruction of the context. In scenarios that just require static
 * registration of tasks at startup, there is no need to access the
 * {@link ScheduledExecutorService} instance itself in application code.
 *
 * <p>Note that {@link ScheduledExecutorService} uses a {@link Runnable} instance
 * that is shared between repeated executions, in contrast to Quartz which
 * instantiates a new Job for each execution.
 *
 * <p>This class is the direct analogue of the
 * {@link org.springframework.scheduling.timer.TimerFactoryBean} class for
 * the JDK 1.3 {@link java.util.Timer} mechanism.
 *
 * @author Juergen Hoeller
 * @since 2.0
 * @see ScheduledExecutorTask
 * @see java.util.concurrent.ScheduledExecutorService
 * @see java.util.concurrent.ScheduledThreadPoolExecutor
 * @see org.springframework.scheduling.timer.TimerFactoryBean
 */
public class ScheduledExecutorFactoryBean implements FactoryBean, InitializingBean, DisposableBean {

	protected final Log logger = LogFactory.getLog(getClass());

	private ScheduledExecutorTask[] scheduledExecutorTasks;

	private int poolSize = 1;

	private ThreadFactory threadFactory = Executors.defaultThreadFactory();

	private RejectedExecutionHandler rejectedExecutionHandler = new ThreadPoolExecutor.AbortPolicy();

	private ScheduledExecutorService executor;


	/**
	 * Register a list of ScheduledExecutorTask objects with the ScheduledExecutorService
	 * that this FactoryBean creates. Depending on each ScheduledExecutorTask's settings,
	 * it will be registered via one of ScheduledExecutorService's schedule methods.
	 * @see java.util.concurrent.ScheduledExecutorService#schedule(java.lang.Runnable, long, java.util.concurrent.TimeUnit)
	 * @see java.util.concurrent.ScheduledExecutorService#scheduleWithFixedDelay(java.lang.Runnable, long, long, java.util.concurrent.TimeUnit)
	 * @see java.util.concurrent.ScheduledExecutorService#scheduleAtFixedRate(java.lang.Runnable, long, long, java.util.concurrent.TimeUnit)
	 */
	public void setScheduledExecutorTasks(ScheduledExecutorTask[] scheduledExecutorTasks) {
		this.scheduledExecutorTasks = scheduledExecutorTasks;
	}

	/**
	 * Set the ScheduledExecutorService's pool size.
	 * Default is 1.
	 */
	public void setPoolSize(int poolSize) {
		this.poolSize = poolSize;
	}

	/**
	 * Set the ThreadFactory to use for the ThreadPoolExecutor's thread pool.
	 * Default is the ThreadPoolExecutor's default thread factory.
	 * @see java.util.concurrent.Executors#defaultThreadFactory()
	 */
	public void setThreadFactory(ThreadFactory threadFactory) {
		this.threadFactory = (threadFactory != null ? threadFactory : Executors.defaultThreadFactory());
	}

	/**
	 * Set the RejectedExecutionHandler to use for the ThreadPoolExecutor.
	 * Default is the ThreadPoolExecutor's default abort policy.
	 * @see java.util.concurrent.ThreadPoolExecutor.AbortPolicy
	 */
	public void setRejectedExecutionHandler(RejectedExecutionHandler rejectedExecutionHandler) {
		this.rejectedExecutionHandler =
				(rejectedExecutionHandler != null ? rejectedExecutionHandler : new ThreadPoolExecutor.AbortPolicy());
	}


    public void afterPropertiesSet() {
        Assert.isTrue(this.poolSize > 0, "The [poolSize] property cannot be set to a value less than 0 (zero).");
        Assert.notEmpty(this.scheduledExecutorTasks, "At least one [ScheduledExecutorTask] must be provided via the [scheduledExecutorTasks] property");

        logger.info("Initializing SchedulerExecutorService");

        this.executor = createExecutor(this.poolSize, this.threadFactory, this.rejectedExecutionHandler);
        registerAllScheduledExecutorTasks();
    }

    /**
     * Create a new ScheduledExecutorService instance.
     * Called by <code>afterPropertiesSet</code>.
     * <p>Default implementation creates a ScheduledThreadPoolExecutor.
     * Can be overridden in subclasses to provide custom
     * ScheduledExecutorService instances.
     * @param poolSize the specified pool size
     * @param threadFactory the ThreadFactory to use
     * @param rejectedExecutionHandler the RejectedExecutionHandler to use
     * @return a new ScheduledExecutorService instance
     * @see #afterPropertiesSet()
     * @see java.util.concurrent.ScheduledThreadPoolExecutor#ScheduledThreadPoolExecutor
     */
    protected ScheduledExecutorService createExecutor(
            int poolSize, ThreadFactory threadFactory, RejectedExecutionHandler rejectedExecutionHandler) {

        return new ScheduledThreadPoolExecutor(poolSize, threadFactory, rejectedExecutionHandler);
    }


	public Object getObject() {
		return this.executor;
	}

	public Class getObjectType() {
		return ScheduledExecutorService.class;
	}

	public boolean isSingleton() {
		return true;
	}


	/**
	 * Cancel the ScheduledExecutorService on bean factory shutdown,
	 * stopping all scheduled tasks.
	 * @see java.util.concurrent.ScheduledExecutorService#shutdown()
	 */
	public void destroy() {
		logger.info("Shutting down ScheduledExecutorService");
		this.executor.shutdown();
	}


    private void registerAllScheduledExecutorTasks() {
        for (int i = 0; i < this.scheduledExecutorTasks.length; i++) {
            ScheduledExecutorTask scheduledTask = this.scheduledExecutorTasks[i];
            if (scheduledTask.isOneTimeTask()) {
                this.executor.schedule(
                        scheduledTask.getRunnable(), scheduledTask.getDelay(), scheduledTask.getTimeUnit());
            }
            else {
                if (scheduledTask.isFixedRate()) {
                    this.executor.scheduleAtFixedRate(
                            scheduledTask.getRunnable(), scheduledTask.getDelay(), scheduledTask.getPeriod(),
                            scheduledTask.getTimeUnit());
                }
                else {
                    this.executor.scheduleWithFixedDelay(
                            scheduledTask.getRunnable(), scheduledTask.getDelay(), scheduledTask.getPeriod(),
                            scheduledTask.getTimeUnit());
                }
            }
        }
    }

}