quartz源码-Schedule启动过程分析

本文主要是介绍quartz源码-Schedule启动过程分析，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

演示demo

public class HelloJob implements Job {private String j1;public void setJ1(String j1) {this.j1 = j1;}@Overridepublic void execute(JobExecutionContext context) throws JobExecutionException {System.out.println("************任务开始执行***********");System.out.println(j1);System.out.println("任务执行结束！");}
}

public class Main {public static void main(String[] args) throws Exception {JobDetail job1 = newJob(HelloJob.class)// 往JobDataMap中传入数据.usingJobData("j1", "我是job1")// 给JobDetail定义一个唯一标识，group+name唯一确定一个JobDetail.withIdentity("job1", "group1").build();Trigger trigger = newTrigger()// 给Trigger定义一个唯一标识，group+name唯一确定一个Trigger.withIdentity("trigger1", "group1")// 往JobDataMap中传入数据.usingJobData("t1", "v1")// 规定Trigger触发时间，这里是每秒触发一次.withSchedule(SimpleScheduleBuilder.simpleSchedule().withIntervalInSeconds(1).repeatForever()).build();Scheduler scheduler = StdSchedulerFactory.getDefaultScheduler();// 把Trigger和JobDetail绑定起来scheduler.scheduleJob(job1, trigger);scheduler.start();}
}

我们主要分析这三行代码

Scheduler scheduler = StdSchedulerFactory.getDefaultScheduler();
scheduler.scheduleJob(job1, trigger);
scheduler.start();

Schedule的获取

Scheduler scheduler = StdSchedulerFactory.getDefaultScheduler();

我们跳转到StdSchedulerFactory涉及到的代码，主要操作如下：

1. 解析quartz.properties文件，把其中的数据存储到变量PropertiesParser cfg;中
2. **获取Scheduler。**会从SchedulerRepository获取Scheduler；获取不到就会通过instantiate()实例化一个新的Scheduler，这个新的Scheduler中的属性的值就是从前面变量PropertiesParser cfg中获取，实例化的Schedule会存储到SchedulerRepository中去。

public class StdSchedulerFactory implements SchedulerFactory {public static Scheduler getDefaultScheduler() throws SchedulerException {StdSchedulerFactory fact = new StdSchedulerFactory();return fact.getScheduler();}public Scheduler getScheduler() throws SchedulerException {if (cfg == null) {// 解析quartz.properties文件，存储到变量PropertiesParser cfg;中initialize();}SchedulerRepository schedRep = SchedulerRepository.getInstance();Scheduler sched = schedRep.lookup(getSchedulerName());if (sched != null) {if (sched.isShutdown()) {schedRep.remove(getSchedulerName());} else {return sched;}}// 实例化Schedulersched = instantiate();return sched;}
}

我们看到SchedulerRepository是个单例模式，用HashMap<String, Scheduler> schedulers;变量存储所有实例化的scheduler，能够保证获取到scheduler唯一性。

public class SchedulerRepository {private HashMap<String, Scheduler> schedulers;private static SchedulerRepository inst;private SchedulerRepository() {schedulers = new HashMap<String, Scheduler>();}public static synchronized SchedulerRepository getInstance() {if (inst == null) {inst = new SchedulerRepository();}return inst;}public synchronized Scheduler lookup(String schedName) {return schedulers.get(schedName);}
}

job和trigger的绑定和存储

scheduler.scheduleJob(job1, trigger);

我们跳转到StdScheduler类中，会发现StdScheduler类什么也没做，只是把其中的方法转去调用QuartzScheduler类中对应的方法。

public class StdScheduler implements Scheduler { private QuartzScheduler sched;public Date scheduleJob(JobDetail jobDetail, Trigger trigger) throws SchedulerException {return sched.scheduleJob(jobDetail, trigger);}
}

来到QuartzScheduler类中对应方法，主要操作如下：

1. 把trigger和job建立绑定关系
2. 计算trigger的第一次触发时间
3. 存储trigger和job

public class QuartzScheduler implements RemotableQuartzScheduler {// 包含创建QuartzScheduler实例所需的所有资源（JobStore、ThreadPool等）。private QuartzSchedulerResources resources;public Date scheduleJob(JobDetail jobDetail,Trigger trigger) throws SchedulerException {validateState();if (jobDetail == null) {throw new SchedulerException("JobDetail cannot be null");}if (trigger == null) {throw new SchedulerException("Trigger cannot be null");}if (jobDetail.getKey() == null) {throw new SchedulerException("Job's key cannot be null");}if (jobDetail.getJobClass() == null) {throw new SchedulerException("Job's class cannot be null");}OperableTrigger trig = (OperableTrigger)trigger;// 1.把trigger和job建立绑定关系// 判断trigger是不是已经绑定了其他job，没有绑定直接绑定给定的jobif (trigger.getJobKey() == null) {trig.setJobKey(jobDetail.getKey());} else if (!trigger.getJobKey().equals(jobDetail.getKey())) {throw new SchedulerException("Trigger does not reference given job!");}trig.validate();// 2.计算第一次点火时间Calendar cal = null;if (trigger.getCalendarName() != null) {cal = resources.getJobStore().retrieveCalendar(trigger.getCalendarName());}Date ft = trig.computeFirstFireTime(cal);if (ft == null) {throw new SchedulerException("Based on configured schedule, the given trigger '" + trigger.getKey() + "' will never fire.");}// 3.存储JobDetail和Triggerresources.getJobStore().storeJobAndTrigger(jobDetail, trig);notifySchedulerListenersJobAdded(jobDetail);notifySchedulerThread(trigger.getNextFireTime().getTime());notifySchedulerListenersSchduled(trigger);return ft;}
}

启动

scheduler.start();

跳转到StdScheduler类

public class StdScheduler implements Scheduler {private QuartzScheduler sched;public void start() throws SchedulerException {sched.start();}
}

跳转到QuartzScheduler#start()方法。这个方法主要是唤醒QuartzSchedulerThread主线程

public void start() throws SchedulerException {if (shuttingDown|| closed) {throw new SchedulerException("The Scheduler cannot be restarted after shutdown() has been called.");}// QTZ-212 : calling new schedulerStarting() method on the listeners// right after entering start()notifySchedulerListenersStarting();if (initialStart == null) {initialStart = new Date();this.resources.getJobStore().schedulerStarted();            startPlugins();} else {resources.getJobStore().schedulerResumed();}// 唤醒QuartzSchedulerThread主线程schedThread.togglePause(false);getLog().info("Scheduler " + resources.getUniqueIdentifier() + " started.");notifySchedulerListenersStarted();
}

这个QuartzSchedulerThread类会在QuartzScheduler实例化的时候就会被创建并开始运行。

public class QuartzScheduler implements RemotableQuartzScheduler {public QuartzScheduler(QuartzSchedulerResources resources, long idleWaitTime, @Deprecated long dbRetryInterval)throws SchedulerException {// ......(省略其他代码)this.schedThread = new QuartzSchedulerThread(this, resources);ThreadExecutor schedThreadExecutor = resources.getThreadExecutor();schedThreadExecutor.execute(this.schedThread);// ......(省略其他代码)}	
}

跳转到QuartzSchedulerThread#run()方法，这个线程开始执行时，paused && !halted.get()这个条件一直满足，会不断执行sigLock.wait(1000L)。直到togglePause(false)调用时，就会改变paused=false，同时会唤醒sigLock.wait(1000L)这个地方，跳出while (paused && !halted.get())这个循环，去触发定时任务。

public class QuartzSchedulerThread extends Thread {private boolean paused;private final Object sigLock = new Object();private AtomicBoolean halted;void togglePause(boolean pause) {synchronized (sigLock) {paused = pause;if (paused) {signalSchedulingChange(0);} else {sigLock.notifyAll();}}}@Overridepublic void run() {int acquiresFailed = 0;while (!halted.get()) {try {// 检查是否需要暂停，当QuartzScheduleThread实例化时，paused=true，进入等待，// 直到调用QuartzScheduler#start()方法时会调用sigLock.notifyAll()。唤醒该线程synchronized (sigLock) {while (paused && !halted.get()) {try {// wait until togglePause(false) is called...sigLock.wait(1000L);} catch (InterruptedException ignore) {}// 暂停时重置失败计数器，这样我们就不用在取消暂停后再次等待acquiresFailed = 0;}if (halted.get()) {break;}}// ......省略其他代码}}}
}

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