scheduledexecutortask.java

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/*
 * Copyright 2002-2005 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.TimeUnit;

/**
 * JavaBean that describes a scheduled executor task, consisting of
 * the Runnable and a delay plus period. Period needs to be specified;
 * there is no point in a default for it.
 *
 * <p>The JDK 1.5 ScheduledExecutorService does not offer more sophisticated
 * scheduling options such as cron expressions. Consider using Quartz for
 * such advanced needs.
 *
 * <p>Note that ScheduledExecutorService uses a Runnable instance that is
 * shared between repeated executions, in contrast to Quartz which
 * instantiates a new Job for each execution.
 *
 * <p>This is the direct analogon of the ScheduledTimerListener class for
 * the JDK 1.3 Timer mechanism.
 *
 * @author Juergen Hoeller
 * @since 2.0
 * @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)
 * @see org.springframework.scheduling.timer.ScheduledTimerTask
 */
public class ScheduledExecutorTask {

	private Runnable runnable;

	private long delay = 0;

	private long period = 0;

	private TimeUnit timeUnit = TimeUnit.MILLISECONDS;

	private boolean fixedRate = false;


	/**
	 * Create a new ScheduledExecutorTask,
	 * to be populated via bean properties.
	 * @see #setDelay
	 * @see #setPeriod
	 * @see #setFixedRate
	 */
	public ScheduledExecutorTask() {
	}

	/**
	 * Create a new ScheduledExecutorTask, with default
	 * one-time execution without delay.
	 * @param executorTask the Runnable to schedule
	 */
	public ScheduledExecutorTask(Runnable executorTask) {
		this.runnable = executorTask;
	}

	/**
	 * Create a new ScheduledExecutorTask, with default
	 * one-time execution with the given delay.
	 * @param executorTask the Runnable to schedule
	 * @param delay the delay before starting the task for the first time (ms)
	 */
	public ScheduledExecutorTask(Runnable executorTask, long delay) {
		this.runnable = executorTask;
		this.delay = delay;
	}

	/**
	 * Create a new ScheduledExecutorTask.
	 * @param executorTask the Runnable to schedule
	 * @param delay the delay before starting the task for the first time (ms)
	 * @param period the period between repeated task executions (ms)
	 * @param fixedRate whether to schedule as fixed-rate execution
	 */
	public ScheduledExecutorTask(Runnable executorTask, long delay, long period, boolean fixedRate) {
		this.runnable = executorTask;
		this.delay = delay;
		this.period = period;
		this.fixedRate = fixedRate;
	}


	/**
	 * Set the Runnable to schedule as executor task.
	 */
	public void setRunnable(Runnable executorTask) {
		this.runnable = executorTask;
	}

	/**
	 * Return the Runnable to schedule as executor task.
	 */
	public Runnable getRunnable() {
		return runnable;
	}

	/**
	 * Set the delay before starting the task for the first time,
	 * in milliseconds. Default is 0, immediately starting the
	 * task after successful scheduling.
	 */
	public void setDelay(long delay) {
		this.delay = delay;
	}

	/**
	 * Return the delay before starting the job for the first time.
	 */
	public long getDelay() {
		return delay;
	}

	/**
	 * Set the period between repeated task executions, in milliseconds.
	 * Default is 0, leading to one-time execution. In case of a positive
	 * value, the task will be executed repeatedly, with the given interval
	 * inbetween executions.
	 * <p>Note that the semantics of the period vary between fixed-rate
	 * and fixed-delay execution.
	 * @see #setFixedRate
     * @see #isOneTimeTask() 
	 */
	public void setPeriod(long period) {
		this.period = period;
	}

	/**
	 * Return the period between repeated task executions.
	 */
	public long getPeriod() {
		return period;
	}

	/**
	 * Specify the time unit for the delay and period values.
	 * Default is milliseconds (<code>TimeUnit.MILLISECONDS</code>).
	 * @see java.util.concurrent.TimeUnit#MILLISECONDS
	 * @see java.util.concurrent.TimeUnit#SECONDS
	 */
	public void setTimeUnit(TimeUnit timeUnit) {
		this.timeUnit = (timeUnit != null ? timeUnit : TimeUnit.MILLISECONDS);
	}

	/**
	 * Return the time unit for the delay and period values.
	 */
	public TimeUnit getTimeUnit() {
		return timeUnit;
	}

	/**
	 * Set whether to schedule as fixed-rate execution, rather than
	 * fixed-delay execution. Default is "false", i.e. fixed delay.
	 * <p>See ScheduledExecutorService javadoc for details on those execution modes.
	 * @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 setFixedRate(boolean fixedRate) {
		this.fixedRate = fixedRate;
	}

	/**
	 * Return whether to schedule as fixed-rate execution.
	 */
	public boolean isFixedRate() {
		return fixedRate;
	}


    /**
     * Is this task only ever going to execute once?
     * @return <code>true</code> if this task is only ever going to execute once.
     * @see #getPeriod() 
     */
    public boolean isOneTimeTask() {
        return this.period < 1;
    }

}