[转]用 Quartz 开展作业调度

[转]用 Quartz 进行作业调度

?Quartz API 采用多面方式在 Java 应用程序中进行任务调度

package com.ibm.developerworks.quartz;import java.util.Date;import org.quartz.Job;import org.quartz.JobExecutionContext;import org.quartz.JobExecutionException;public class SimpleQuartzJob implements Job{public SimpleQuartzJob(){}public void execute(JobExecutionContext context)throws JobExecutionException{System.out.println("In SimpleQuartzJob - executing its JOB at "+ new Date() + " by " + context.getTrigger().getName());}}

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请注意，execute 方法接受一个 JobExecutionContext 对象作为参数。这个对象提供了作业实例的运行时上下文。特别地，它提供了对调度器和触发器的访问，这两者协作来启动作业以及作业的 JobDetail 对象的执行。Quartz 通过把作业的状态放在 JobDetail 对象中并让 JobDetail 构造函数启动一个作业的实例，分离了作业的执行和作业周围的状态。JobDetail 对象储存作业的侦听器、群组、数据映射、描述以及作业的其他属性。

public void task() throws SchedulerException { // Initiate a Schedule Factory SchedulerFactory schedulerFactory = new StdSchedulerFactory(); // Retrieve a scheduler from schedule factory Scheduler scheduler = schedulerFactory.getScheduler(); // current time long ctime = System.currentTimeMillis(); // Initiate JobDetail with job name, job group, and executable job class JobDetail jobDetail = new JobDetail("jobDetail-s1", "jobDetailGroup-s1", SimpleQuartzJob.class); // Initiate SimpleTrigger with its name and group name SimpleTrigger simpleTrigger = new SimpleTrigger("simpleTrigger", "triggerGroup-s1"); // set its start up time simpleTrigger.setStartTime(new Date(ctime)); // set the interval, how often the job should run (10 seconds here) simpleTrigger.setRepeatInterval(10000); // set the number of execution of this job, set to 10 times. // It will run 10 time and exhaust. simpleTrigger.setRepeatCount(100); // set the ending time of this job. // We set it for 60 seconds from its startup time here // Even if we set its repeat count to 10, // this will stop its process after 6 repeats as it gets it endtime by// then. // simpleTrigger.setEndTime(new Date(ctime + 60000L)); // set priority of trigger. If not set, the default is 5 // simpleTrigger.setPriority(10); // schedule a job with JobDetail and Trigger scheduler.scheduleJob(jobDetail, simpleTrigger); // start the scheduler scheduler.start(); }

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public void task() throws SchedulerException { // Initiate a Schedule Factory SchedulerFactory schedulerFactory = new StdSchedulerFactory(); // Retrieve a scheduler from schedule factory Scheduler scheduler = schedulerFactory.getScheduler(); // current time long ctime = System.currentTimeMillis(); // Initiate JobDetail with job name, job group, and executable job class JobDetail jobDetail = new JobDetail("jobDetail2", "jobDetailGroup2", SimpleQuartzJob.class); // Initiate CronTrigger with its name and group name CronTrigger cronTrigger = new CronTrigger("cronTrigger", "triggerGroup2"); try { // setup CronExpression CronExpression cexp = new CronExpression("0/5 * * * * ?"); // Assign the CronExpression to CronTrigger cronTrigger.setCronExpression(cexp); } catch (Exception e) { e.printStackTrace(); } // schedule a job with JobDetail and Trigger scheduler.scheduleJob(jobDetail, cronTrigger); // start the scheduler scheduler.start(); }?属性名称值public void task() throws SchedulerException { // Initiate a Schedule Factory SchedulerFactory schedulerFactory = new StdSchedulerFactory(); // Retrieve a scheduler from schedule factory Scheduler scheduler = schedulerFactory.getScheduler(); String[] triggerGroups; String[] triggers; triggerGroups = scheduler.getTriggerGroupNames(); for (int i = 0; i < triggerGroups.length; i++) { triggers = scheduler.getTriggerNames(triggerGroups[i]); for (int j = 0; j < triggers.length; j++) { Trigger tg = scheduler.getTrigger(triggers[j], triggerGroups[i]); if (tg instanceof SimpleTrigger && tg.getName().equals("simpleTrigger")) { ((SimpleTrigger)tg).setRepeatCount(100); // reschedule the job scheduler.rescheduleJob(triggers[j], triggerGroups[i], tg); // unschedule the job // scheduler.unscheduleJob(triggersInGroup[j],// triggerGroups[i]); } } } // start the scheduler scheduler.start(); }?

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图 2 显示了数据库在应用程序停止后的情况。在这个图中，TIMES_TRIGGERED 被设为 19，表示作业运行的次数。

图 2. 同一数据在 19 次迭代之后


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当再次启动应用程序时，REPEAT_COUNT 被更新。这在图 3 中很明显。在图 3 中可以看到 REPEAT_COUNT 被更新为 81，所以新的 REPEAT_COUNT 等于前面的 REPEAT_COUNT 值减去前面的 TIMES_TRIGGERED 值。而且，在图 3 中还看到新的 TIMES_TRIGGERED 值是 7，表示作业从应用程序重新启动以来，又触发了 7 次。

图 3. 第 2 次运行 7 次迭代之后的数据


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当再次停止应用程序之后，REPEAT_COUNT 值再次更新。如图 4 所示，应用程序已经停止，还没有重新启动。同样，REPEAT_COUNT 值更新成前一个 REPEAT_COUNT 值减去前一个 TIMES_TRIGGERED 值。

图 4. 再次运行触发器之前的初始数据


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org.quartz.threadPool.class = org.quartz.simpl.SimpleThreadPoolorg.quartz.threadPool.threadCount = 10org.quartz.threadPool.threadPriority = 5org.quartz.threadPool.threadsInheritContextClassLoaderOfInitializingThread = true# Using RAMJobStore## if using RAMJobStore, please be sure that you comment out the following## - org.quartz.jobStore.tablePrefix, ## - org.quartz.jobStore.driverDelegateClass, ## - org.quartz.jobStore.dataSource#org.quartz.jobStore.class = org.quartz.simpl.RAMJobStore# Using JobStoreTX## Be sure to run the appropriate script(under docs/dbTables) first to create tablesorg.quartz.jobStore.class = org.quartz.impl.jdbcjobstore.JobStoreTX# Configuring JDBCJobStore with the Table Prefixorg.quartz.jobStore.tablePrefix = QRTZ_# Using DriverDelegateorg.quartz.jobStore.driverDelegateClass = org.quartz.impl.jdbcjobstore.StdJDBCDelegate# Using datasourceorg.quartz.jobStore.dataSource = qzDS# Define the datasource to useorg.quartz.dataSource.qzDS.driver = com.ibm.db2.jcc.DB2Driverorg.quartz.dataSource.qzDS.URL = jdbc:db2://localhost:50000/dbnameorg.quartz.dataSource.qzDS.user = dbuseridorg.quartz.dataSource.qzDS.password = passwordorg.quartz.dataSource.qzDS.maxConnections = 30?

结束语

Quartz 作业调度框架所提供的 API 在两方面都表现极佳：既全面强大，又易于使用。Quartz 可以用于简单的作业触发，也可以用于复杂的 JDBC 持久的作业存储和执行。OpenSymphony 在开放源码世界中成功地填补了一个空白，过去繁琐的作业调度现在对开发人员来说不过是小菜一碟。

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