一分钟掌握Java Quartz定时任务

package org.quartz.examples.example1;
import java.util.Date;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.quartz.Job;
import org.quartz.JobExecutionContext;
import org.quartz.JobExecutionException;
/**
 * <p>
 * This is just a simple job that says "Hello" to the world.
 * </p>
 * 
 * @author Bill Kratzer
 */
public class HelloJob implements Job {
    private static Logger _log = LoggerFactory.getLogger(HelloJob.class);
    /**
     * <p>
     * Empty constructor for job initilization
     * </p>
     * <p>
     * Quartz requires a public empty constructor so that the
     * scheduler can instantiate the class whenever it needs.
     * </p>
     */
    public HelloJob() {
    }
    /**
     * <p>
     * Called by the <code>{@link org.quartz.Scheduler}</code> when a
     * <code>{@link org.quartz.Trigger}</code> fires that is associated with
     * the <code>Job</code>.
     * </p>
     * 
     * @throws JobExecutionException
     *             if there is an exception while executing the job.
     */
    public void execute(JobExecutionContext context)
        throws JobExecutionException {
        // Say Hello to the World and display the date/time
        _log.info("Hello World! - " + new Date());
    }
}

 package org.quartz.examples.example1;
 import org.quartz.JobDetail;
 import org.quartz.Scheduler;
 import org.quartz.SchedulerFactory;
 import org.quartz.Trigger;
 import org.quartz.impl.StdSchedulerFactory;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import java.util.Date;
 import static org.quartz.DateBuilder.evenMinuteDate;
 import static org.quartz.JobBuilder.newJob;
 import static org.quartz.TriggerBuilder.newTrigger;
 /**
  * This Example will demonstrate how to start and shutdown the Quartz scheduler and how to schedule a job to run in
  * Quartz.
  *
  * @author Bill Kratzer
  */
 public class SimpleExample {
     public void run() throws Exception {
         Logger log = LoggerFactory.getLogger(SimpleExample.class);
         log.info("------- Initializing ----------------------");
         // 1. 创建一个scheduler
         SchedulerFactory sf = new StdSchedulerFactory();
         Scheduler sched = sf.getScheduler();
         log.info("------- Initialization Complete -----------");
         // computer a time that is on the next round minute
         Date runTime = evenMinuteDate(new Date());
         log.info("------- Scheduling Job  -------------------");
         // 2. 指定一个job
         JobDetail job = newJob(HelloJob.class).withIdentity("job1", "group1").build();
         // 3. 指定一个trigger
         Trigger trigger = newTrigger().withIdentity("trigger1", "group1").startAt(runTime).build();
         // 4. 绑定job和trigger
         sched.scheduleJob(job, trigger);
         log.info(job.getKey() + " will run at: " + runTime);
         // 5. 执行
         sched.start();
         log.info("------- Started Scheduler -----------------");
         // wait long enough so that the scheduler as an opportunity to
         // run the job!
         log.info("------- Waiting 65 seconds... -------------");
         try {
             // wait 65 seconds to show job
             Thread.sleep(65L * 1000L);
             // executing...
         } catch (Exception e) {
             //
         }
         // shut down the scheduler
         log.info("------- Shutting Down ---------------------");
         sched.shutdown(true);
         log.info("------- Shutdown Complete -----------------");
     }
     public static void main(String[] args) throws Exception {
         SimpleExample example = new SimpleExample();
         example.run();
     }
 }

public void run() {
    qs.addInternalSchedulerListener(this);
    try {
        // ...省略很多源代码
        do {
            // ...省略很多源代码
            try {
                begin();
            } catch (SchedulerException se) {
                // ... 省略源代码
            }
            // ... 省略源代码
            try {
                log.debug("Calling execute on job " + jobDetail.getKey());
                // 这里负责执行job的execute函数
                job.execute(jec);
                endTime = System.currentTimeMillis();
            } catch (JobExecutionException jee) {
                // ... 省略源代码
            } catch (Throwable e) {
                // ... 省略源代码
            }
            // ...省略很多源代码
            try {
                complete(true);
            } catch (SchedulerException se) {
                // ... 省略源代码
            }
            // ...省略很多源代码
        } while (true);
    } finally {
        qs.removeInternalSchedulerListener(this);
    }
}

@Override
public void run() {
    int acquiresFailed = 0;
    while (!halted.get()) {
        // ...省略很多源代码
        // 源代码279行
        int availThreadCount = qsRsrcs.getThreadPool().blockForAvailableThreads();
        // ...省略很多源代码
        if(availThreadCount > 0) { 
            // ...省略很多源代码
            // 取下一个trigger，周期是30秒取一次
            triggers = qsRsrcs.getJobStore().acquireNextTriggers(
                now + idleWaitTime, Math.min(availThreadCount, qsRsrcs.getMaxBatchSize()), qsRsrcs.getBatchTimeWindow());
            // ...省略很多源代码
            // 触发trigger
            List<TriggerFiredResult> res = qsRsrcs.getJobStore().triggersFired(triggers);
            // ...省略很多源代码
            // 释放trigger，当bndle的结果是null就释放trigger
            if (bndle == null) {
                qsRsrcs.getJobStore().releaseAcquiredTrigger(triggers.get(i));
                continue;
            }
            // ...省略很多源代码
            JobRunShell shell = null;
            try {
                shell = qsRsrcs.getJobRunShellFactory().createJobRunShell(bndle);
                shell.initialize(qs);
            } catch (SchedulerException se) {
                qsRsrcs.getJobStore().triggeredJobComplete(triggers.get(i), bndle.getJobDetail(), CompletedExecutionInstruction.SET_ALL_JOB_TRIGGERS_ERROR);
                continue;
            }
            // 这里调用JobRunShell
            if (qsRsrcs.getThreadPool().runInThread(shell) == false) {
                // ...省略很多源代码
            }
        }  
    }
}

    /**
     * Execute the given callback having optionally acquired the given lock.
     * This uses the non-managed transaction connection.
     * 
     * @param lockName The name of the lock to acquire, for example
     * "TRIGGER_ACCESS".  If null, then no lock is acquired, but the
     * lockCallback is still executed in a non-managed transaction. 
     */
    protected <T> T executeInNonManagedTXLock(
            String lockName, 
            TransactionCallback<T> txCallback, final TransactionValidator<T> txValidator) throws JobPersistenceException {
        boolean transOwner = false;
        Connection conn = null;
        try {
            if (lockName != null) {
                // If we aren't using db locks, then delay getting DB connection 
                // until after acquiring the lock since it isn't needed.
                if (getLockHandler().requiresConnection()) {
                    conn = getNonManagedTXConnection();
                }
                transOwner = getLockHandler().obtainLock(conn, lockName);
            }
            if (conn == null) {
                conn = getNonManagedTXConnection();
            }
            final T result = txCallback.execute(conn);
            try {
                commitConnection(conn);
            } catch (JobPersistenceException e) {
                rollbackConnection(conn);
                if (txValidator == null || !retryExecuteInNonManagedTXLock(lockName, new TransactionCallback<Boolean>() {
                    @Override
                    public Boolean execute(Connection conn) throws JobPersistenceException {
                        return txValidator.validate(conn, result);
                    }
                })) {
                    throw e;
                }
            }
            Long sigTime = clearAndGetSignalSchedulingChangeOnTxCompletion();
            if(sigTime != null && sigTime >= 0) {
                signalSchedulingChangeImmediately(sigTime);
            }
            return result;
        } catch (JobPersistenceException e) {
            rollbackConnection(conn);
            throw e;
        } catch (RuntimeException e) {
            rollbackConnection(conn);
            throw new JobPersistenceException("Unexpected runtime exception: "
                    + e.getMessage(), e);
        } finally {
            try {
                releaseLock(lockName, transOwner);
            } finally {
                cleanupConnection(conn);
            }
        }
    }