Quartz.net官方开发指南 第二课:Jobs And Triggers
正如前面所提到的那样,通过实现IJob接口来使你的.NET组件可以很简单地被scheduler执行。下面是IJob接口:
{
/// <summary>
/// The interface to be implemented by classes which represent a 'job' to be
/// performed.
/// </summary>
/// <remarks>
/// Instances of this interface must have a <see langword="public" />
/// no-argument constructor. <see cref="JobDataMap" /> provides a mechanism for 'instance member data'
/// that may be required by some implementations of this interface.
/// </remarks>
/// <seealso cref="JobDetail" />
/// <seealso cref="IStatefulJob" />
/// <seealso cref="Trigger" />
/// <seealso cref="IScheduler" />
/// <author>James House</author>
/// <author>Marko Lahma (.NET)</author>
public interface IJob
{
/// <summary>
/// Called by the <see cref="IScheduler" /> when a <see cref="Trigger" />
/// fires that is associated with the <see cref="IJob" />.
/// </summary>
/// <remarks>
/// The implementation may wish to set a result object on the
/// JobExecutionContext before this method exits. The result itself
/// is meaningless to Quartz, but may be informative to
/// <see cref="IJobListener" />s or
/// <see cref="ITriggerListener" />s that are watching the job's
/// execution.
/// </remarks>
/// <param name="context">The execution context.</param>
void Execute(JobExecutionContext context);
}
}
log.Info("------- Initializing -------------------");
// First we must get a reference to a scheduler
ISchedulerFactory sf = new StdSchedulerFactory();
IScheduler sched = sf.GetScheduler();
log.Info("------- Initialization Complete --------");
log.Info("------- Scheduling Jobs ----------------");
// jobs can be scheduled before sched.start() has been called
// get a "nice round" time a few seconds in the future
DateTime ts = TriggerUtils.GetNextGivenSecondDate(null, 15);
// job1 will only fire once at date/time "ts"
JobDetail job = new JobDetail("job1", "group1", typeof (SimpleJob));
SimpleTrigger trigger = new SimpleTrigger("trigger1", "group1", ts);
// schedule it to run!
DateTime ft = sched.ScheduleJob(job, trigger);
log.Info(string.Format("{0} will run at: {1} and repeat: {2} times, every {3} seconds",
job.FullName, ft.ToString("r"), trigger.RepeatCount, (trigger.RepeatInterval/1000)));
// job2 will only fire once at date/time "ts"
job = new JobDetail("job2", "group1", typeof (SimpleJob));
trigger = new SimpleTrigger("trigger2", "group1", "job2", "group1", ts, null, 0, 0);
ft = sched.ScheduleJob((job), trigger);
log.Info(string.Format("{0} will run at: {1} and repeat: {2} times, every {3} seconds",
job.FullName, ft.ToString("r"), trigger.RepeatCount, (trigger.RepeatInterval/1000)));
// job3 will run 11 times (run once and repeat 10 more times)
// job3 will repeat every 10 seconds (10000 ms)
job = new JobDetail("job3", "group1", typeof (SimpleJob));
trigger = new SimpleTrigger("trigger3", "group1", "job3", "group1", ts, null, 10, 10000L);
ft = sched.ScheduleJob(job, trigger);
log.Info(string.Format("{0} will run at: {1} and repeat: {2} times, every {3} seconds",
job.FullName, ft.ToString("r"), trigger.RepeatCount, (trigger.RepeatInterval/1000)));
// the same job (job3) will be scheduled by a another trigger
// this time will only run every 70 seocnds (70000 ms)
trigger = new SimpleTrigger("trigger3", "group2", "job3", "group1", ts, null, 2, 70000L);
ft = sched.ScheduleJob(trigger);
log.Info(string.Format("{0} will [also] run at: {1} and repeat: {2} times, every {3} seconds",
job.FullName, ft.ToString("r"), trigger.RepeatCount, (trigger.RepeatInterval/1000)));
// job4 will run 6 times (run once and repeat 5 more times)
// job4 will repeat every 10 seconds (10000 ms)
job = new JobDetail("job4", "group1", typeof (SimpleJob));
trigger = new SimpleTrigger("trigger4", "group1", "job4", "group1", ts, null, 5, 10000L);
ft = sched.ScheduleJob(job, trigger);
log.Info(string.Format("{0} will run at: {1} and repeat: {2} times, every {3} seconds",
job.FullName, ft.ToString("r"), trigger.RepeatCount, (trigger.RepeatInterval/1000)));
// job5 will run once, five minutes past "ts" (300 seconds past "ts")
job = new JobDetail("job5", "group1", typeof (SimpleJob));
trigger = new SimpleTrigger("trigger5", "group1", "job5", "group1", ts.AddMilliseconds(300*1000), null, 0, 0);
ft = sched.ScheduleJob(job, trigger);
log.Info(string.Format("{0} will run at: {1} and repeat: {2} times, every {3} seconds",
job.FullName, ft.ToString("r"), trigger.RepeatCount, (trigger.RepeatInterval/1000)));
// job6 will run indefinitely, every 50 seconds
job = new JobDetail("job6", "group1", typeof (SimpleJob));
trigger =
new SimpleTrigger("trigger6", "group1", "job6", "group1", ts, null, SimpleTrigger.REPEAT_INDEFINITELY,
50000L);
ft = sched.ScheduleJob(job, trigger);
log.Info(string.Format("{0} will run at: {1} and repeat: {2} times, every {3} seconds",
job.FullName, ft.ToString("r"), trigger.RepeatCount, (trigger.RepeatInterval/1000)));
log.Info("------- Starting Scheduler ----------------");
// All of the jobs have been added to the scheduler, but none of the jobs
// will run until the scheduler has been started
sched.Start();
log.Info("------- Started Scheduler -----------------");
// jobs can also be scheduled after start() has been called
// job7 will repeat 20 times, repeat every five minutes
job = new JobDetail("job7", "group1", typeof (SimpleJob));
trigger = new SimpleTrigger("trigger7", "group1", "job7", "group1", ts, null, 20, 300000);
ft = sched.ScheduleJob(job, trigger);
log.Info(string.Format("{0} will run at: {1} and repeat: {2} times, every {3} seconds",
job.FullName, ft.ToString("r"), trigger.RepeatCount, (trigger.RepeatInterval/1000)));
// jobs can be fired directly (rather than waiting for a trigger)
job = new JobDetail("job8", "group1", typeof (SimpleJob));
job.Durable = (true);
sched.AddJob(job, true);
log.Info("'Manually' triggering job8");
sched.TriggerJob("job8", "group1");
log.Info("------- Waiting 30 seconds --------------");
try
{
// wait 30 seconds to show jobs
Thread.Sleep(30*1000);
// executing
}
catch (ThreadInterruptedException)
{
}
// jobs can be re-scheduled
// job 7 will run immediately and repeat 10 times for every second
log.Info("------- Rescheduling --------------------");
trigger = new SimpleTrigger("trigger7", "group1", "job7", "group1", DateTime.Now, null, 10, 1000L);
NullableDateTime ft2 = sched.RescheduleJob("trigger7", "group1", trigger);
if (ft2.HasValue)
{
log.Info("job7 rescheduled to run at: " + ft2.Value.ToString("r"));
}
else
{
log.Error("Reschedule failed, date was null");
}
log.Info("------- Waiting five minutes ------------");
try
{
// wait five minutes to show jobs
Thread.Sleep(2*1000);
// executing
}
catch (ThreadInterruptedException)
{
}
log.Info("------- Shutting Down ---------------------");
sched.Shutdown(true);
log.Info("------- Shutdown Complete -----------------");
// display some stats about the schedule that just ran
SchedulerMetaData metaData = sched.GetMetaData();
log.Info(string.Format("Executed {0} jobs.", metaData.NumJobsExecuted));
这样,你会猜想出,当Job触发器触发时(在某个时刻),Execute (..)就被scheduler所调用。JobExecutionContext对象被传递给这个方法,它为Job实例提供了它的“运行时”环境-一个指向执行这个IJob实例的Scheduler句柄,一个指向触发该次执行的触发器的句柄,IJob的JobDetail对象以及一些其他的条目。
JobDetail对象由Quartz客户端在Job被加入到scheduler时创建。它包含了Job的各种设置属性以及一个JobDataMap对象,这个对象被用来存储给定Job类实例的状态信息。
Trigger对象被用来触发jobs的执行。你希望将任务纳入到进度,要实例化一个Trigger并且“调整”它的属性以满足你想要的进度安排。Triggers也有一个JobDataMap与之关联,这非常有利于向触发器所触发的Job传递参数。Quartz打包了很多不同类型的Trigger,但最常用的Trigge类是SimpleTrigger和CronTrigger。
SimpleTrigger用来触发只需执行一次或者在给定时间触发并且重复N次且每次执行延迟一定时间的任务。CronTrigger按照日历触发,例如“每个周五”,每个月10日中午或者10:15分。
为什么要分为Jobs和Triggers?很多任务日程管理器没有将Jobs和Triggers进行区分。一些产品中只是将“job”简单地定义为一个带有一些小任务标识的执行时间。其他产品则更像Quartz中job和trigger的联合。而开发Quartz的时候,我们决定对日程和按照日程执行的工作进行分离。(从我们的观点来看)这有很多好处。
例如:jobs可以被创建并且存储在job scheduler中,而不依赖于trigger,而且,很多triggers可以关联一个job.另外的好处就是这种“松耦合”能使与日程中的Job相关的trigger过期后重新配置这些Job,这样以后就能够重新将这些Job纳入日程而不必重新定义它们。这样就可以更改或者替换trigger而不必重新定义与之相连的job标识符。
当向Quartz scheduler中注册Jobs 和Triggers时,它们要给出标识它们的名字。Jobs 和Triggers也可以被放入“组”中。“组”对于后续维护过程中,分类管理Jobs和Triggers非常有用。Jobs和Triggers的名字在组中必须唯一,换句话说,Jobs和Triggers真实名字是它的名字+组。如果使Job或者Trigger的组为‘null’,这等价于将其放入缺省的Scheduler.DEFAULT_GROUP组中。
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