Java Quartz Scheduler状态

Question

我试着用下面的代码检查Quartz Scheduler状态，但是状态返回令人困惑。为什么在我关闭调度器之后，isStarted状态仍然是真的，在我重新启动调度器之后，isShutDown状态是真的。

if (logger.isLoggable(Level.INFO)) {
    logger.info("Before: Stand by: "
        + this.scheduler.isInStandbyMode() + ", Start: "
        + this.scheduler.isStarted() + ", Shutdown: "
        + this.scheduler.isShutdown());
}

this.scheduler.start();

if (logger.isLoggable(Level.INFO)) {
    logger.info("After: Stand by: "
        + this.scheduler.isInStandbyMode() + ", Start: "
        + this.scheduler.isStarted() + ", Shutdown: "
        + this.scheduler.isShutdown());
}

//Shutdown scheduler
this.scheduler.shutdown(true);
if (logger.isLoggable(Level.INFO)) {
    logger.info("Schedule stop: Stand by: "
            + this.scheduler.isInStandbyMode() + ", Start: "
            + this.scheduler.isStarted() + ", Shutdown: "
            + this.scheduler.isShutdown());
}

//Restart scheduler
this.scheduler.start();
if (logger.isLoggable(Level.INFO)) {
    logger.info("schedule start: Stand by: "
            + this.scheduler.isInStandbyMode() + ", Start: "
            + this.scheduler.isStarted() + ", Shutdown: "
            + this.scheduler.isShutdown());
}

结果是

• 信息:准备:真，开始:假，关机:假
• 信息:准备:错误，开始:真，关闭:假
• 计划停止:等待:真，开始:真，关机:真
• 计划开始:准备:真，开始:真，关机:真

Answer 1

虽然这看起来像是一个bug，但实际上是通过设计来实现的。isStarted()和isShutdown()方法不报告Quartz Scheduler的当前状态，而是只用于确定Scheduler在过去某个时候是否已经启动或关闭。请参阅以下Javadoc：

/**
 * Whether the scheduler has been started.  
 * 
 * <p>
 * Note: This only reflects whether <code>{@link #start()}</code> has ever
 * been called on this Scheduler, so it will return <code>true</code> even 
 * if the <code>Scheduler</code> is currently in standby mode or has been 
 * since shutdown.
 * </p>
 * 
 * @see #start()
 * @see #isShutdown()
 * @see #isInStandbyMode()
 */    
boolean isStarted() throws SchedulerException;