ScheduledExecutorService定时周期执行指定的任务

 public ScheduledFuture<?> scheduleAtFixedRate(Runnable command,
				long initialDelay,
				long period,
				TimeUnit unit);

public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command,
				long initialDelay,
				long delay,
				TimeUnit unit);

/**
 * 以固定周期频率执行任务
 */
public static void executeFixedRate() {
	ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
	executor.scheduleAtFixedRate(
			new EchoServer(),
			0,
			100,
			TimeUnit.MILLISECONDS);
}

/**
 * 以固定延迟时间进行执行
 * 本次任务执行完成后，需要延迟设定的延迟时间，才会执行新的任务
 */
public static void executeFixedDelay() {
	ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
	executor.scheduleWithFixedDelay(
			new EchoServer(),
			0,
			100,
			TimeUnit.MILLISECONDS);
}

/**
 * 每天晚上8点执行一次
 * 每天定时安排任务进行执行
 */
public static void executeEightAtNightPerDay() {
	ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
	long oneDay = 24 * 60 * 60 * 1000;
	long initDelay  = getTimeMillis("20:00:00") - System.currentTimeMillis();
	initDelay = initDelay > 0 ? initDelay : oneDay + initDelay;

	executor.scheduleAtFixedRate(
			new EchoServer(),
			initDelay,
			oneDay,
			TimeUnit.MILLISECONDS);
}

/**
 * 获取指定时间对应的毫秒数
 * @param time "HH:mm:ss"
 * @return
 */
private static long getTimeMillis(String time) {
	try {
		DateFormat dateFormat = new SimpleDateFormat("yy-MM-dd HH:mm:ss");
		DateFormat dayFormat = new SimpleDateFormat("yy-MM-dd");
		Date curDate = dateFormat.parse(dayFormat.format(new Date()) + " " + time);
		return curDate.getTime();
	} catch (ParseException e) {
		e.printStackTrace();
	}
	return 0;
}

class EchoServer implements Runnable {
	@Override
	public void run() {
		try {
			Thread.sleep(50);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		System.out.println("This is a echo server. The current time is " +
				System.currentTimeMillis() + ".");
	}
}

* Creates and executes a periodic action that becomes enabled first
* after the given initial delay, and subsequently with the given
* period; that is executions will commence after
* <tt>initialDelay</tt> then <tt>initialDelay+period</tt>, then
* <tt>initialDelay + 2 * period</tt>, and so on.
* If any execution of the task
* encounters an exception, subsequent executions are suppressed.
* Otherwise, the task will only terminate via cancellation or
* termination of the executor.  If any execution of this task
* takes longer than its period, then subsequent executions
* may start late, but will not concurrently execute.

<bean id="myTimedTask" class="com.study.MyTimedTask"/>

<bean id="doMyTimedTask" class="org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean">
	<property name="targetObject" ref="myTimedTask"/>
	<property name="targetMethod" value="execute"/>
	<property name="concurrent" value="false"/>
</bean>

<bean id="myTimedTaskTrigger" class="org.springframework.scheduling.quartz.CronTriggerBean">
	<property name="jobDetail" ref="doMyTimedTask"/>
	<property name="cronExpression" value="0 0 2 * ?"/>
</bean>

<bean id="doScheduler" class="org.springframework.scheduling.quartz.SchedulerFactoryBean">
	<property name="triggers">
		<list>
			<ref local="myTimedTaskTrigger"/>
		</list>
	</property>
</bean>

<bean id="doScheduler" class="org.springframework.scheduling.quartz.SchedulerFactoryBean">
	<property name="triggers">
		<list>
			<bean class="org.springframework.scheduling.quartz.CronTriggerBean">
				<property name="jobDetail"/>
					<bean id="doMyTimedTask" class="org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean">
						<property name="targetObject">
							<bean class="com.study.MyTimedTask"/>
						</property>
						<property name="targetMethod" value="execute"/>
						<property name="concurrent" value="false"/>
					</bean>
				</property>
				<property name="cronExpression" value="0 0 2 * ?"/>
			</bean>
		</list>
	</property>
</bean>