j-schedule java 定时执行任务

package org.tiling.scheduling; import java.util.Date; import java.util.Timer; import java.util.TimerTask; /** * A facility for threads to schedule recurring tasks for future execution in a background thread. * <p> * This class is thread-safe: multiple threads can share a single <code>Scheduler</code> object without the need for external synchronization. * <p> * Implementation note: internally <code>Scheduler</code> uses a <code>java.util.Timer</code> to schedule tasks. */ public class Scheduler { class SchedulerTimerTask extends TimerTask { private SchedulerTask schedulerTask; private ScheduleIterator iterator; public SchedulerTimerTask(SchedulerTask schedulerTask, ScheduleIterator iterator) { this.schedulerTask = schedulerTask; this.iterator = iterator; } public void run() { schedulerTask.run(); reschedule(schedulerTask, iterator); } } private final Timer timer = new Timer(); public Scheduler() { } /** * Terminates this <code>Scheduler</code>, discarding any currently scheduled tasks. Does not interfere with a currently executing task (if it exists). Once a scheduler has been terminated, its execution thread terminates gracefully, and no more tasks may be scheduled on it. * <p> * Note that calling this method from within the run method of a scheduler task that was invoked by this scheduler absolutely guarantees that the ongoing task execution is the last task execution that will ever be performed by this scheduler. * <p> * This method may be called repeatedly; the second and subsequent calls have no effect. */ public void cancel() { timer.cancel(); } /** * Schedules the specified task for execution according to the specified schedule. If times specified by the <code>ScheduleIterator</code> are in the past they are scheduled for immediate execution. * <p> * @param schedulerTask task to be scheduled * @param iterator iterator that describes the schedule * @throws IllegalStateException if task was already scheduled or cancelled, scheduler was cancelled, or scheduler thread terminated. */ public void schedule(SchedulerTask schedulerTask, ScheduleIterator iterator) { Date time = iterator.next(); if (time == null) { schedulerTask.cancel(); } else { synchronized(schedulerTask.lock) { if (schedulerTask.state != SchedulerTask.VIRGIN) { throw new IllegalStateException("Task already scheduled " + "or cancelled"); } schedulerTask.state = SchedulerTask.SCHEDULED; schedulerTask.timerTask = new SchedulerTimerTask(schedulerTask, iterator); timer.schedule(schedulerTask.timerTask, time); } } } private void reschedule(SchedulerTask schedulerTask, ScheduleIterator iterator) { Date time = iterator.next(); if (time == null) { schedulerTask.cancel(); } else { synchronized(schedulerTask.lock) { if (schedulerTask.state != SchedulerTask.CANCELLED) { schedulerTask.timerTask = new SchedulerTimerTask(schedulerTask, iterator); timer.schedule(schedulerTask.timerTask, time); } } } } }