【原创】Quartz代码详解

阅读目录

• 简单介绍
• 章节1：Quartz简单实例
• 章节2：Job、JobDetail、JobBuilder
• 章节3：Trigger、TriggerBuilder
• 章节4：Scheduler
• 章节5：JobListener、SchedulerListener、TriggerListener
• 章节6：Cron表达式
• 章节7：参考链接

简单介绍

在实际编程中，我们经常会遇到定时任务，或是隔一段时间执行指定任务，例如：

1. 在每月的30号9:00统计人员出勤情况；

2. 每隔10分钟执行一次入库操作；

上面的例子中，需要执行的操作就是Job（作业），而在指定时间或者间隔固定时间去触发这个Job的就是Trigger（触发器），而把二者联系在一起的就是Scheduler（调度器）；

Quartz主要要理解三个方面：

1. Scheduler：调度器，将Job和Trigger关联起来；
   
2. Job          ：需要执行的作业；
   
3. Trigger    ：触发器，指定执行的时间，主要包括两种方式：

<1>指定时间：如每月15号9:00，或者每天的12:00等等；

<2>间隔时间：如每隔10分钟执行一次，每隔2h执行一次等等；

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一、Quartz简单实例

下面给出一个简单的示例：

        
        
        
        

         
         
         
         SchedulerFactory schedFact = new org.quartz.impl.StdSchedulerFactory();
        
        
        
        
        
        
        
        

         
         
         
          
        
        
        
        
        
        
        
        

         
         
         
           Scheduler sched = schedFact.getScheduler();
        
        
        
        
        
        
        
        

         
         
         
          
        
        
        
        
        
        
        
        

         
         
         
           sched.start();
        
        
        
        
        
        
        
        

         
         
         
          
        
        
        
        
        
        
        
        

         
         
         
           // define the job and tie it to our HelloJob class
        
        
        
        
        
        
        
        

         
         
         
           JobDetail job = newJob(HelloJob.class)
        
        
        
        
        
        
        
        

         
         
         
               .withIdentity("myJob", "group1")
        
        
        
        
        
        
        
        

         
         
         
               .build();
        
        
        
        
        
        
        
        

         
         
         
          
        
        
        
        
        
        
        
        

         
         
         
           // Trigger the job to run now, and then every 40 seconds
        
        
        
        
        
        
        
        

         
         
         
           trigger = newTrigger()
        
        
        
        
        
        
        
        

         
         
         
               .withIdentity("myTrigger", "group1")
        
        
        
        
        
        
        
        

         
         
         
               .startNow()
        
        
        
        
        
        
        
        

         
         
         
               .withSchedule(simpleSchedule()
        
        
        
        
        
        
        
        

         
         
         
                   .withIntervalInSeconds(40)
        
        
        
        
        
        
        
        

         
         
         
                   .repeatForever())
        
        
        
        
        
        
        
        

         
         
         
               .build();
        
        
        
        
        
        
        
        

         
         
         
          
        
        
        
        
        
        
        
        

         
         
         
           // Tell quartz to schedule the job using our trigger
        
        
        
        
        
        
        
        

         
         
         
           sched.scheduleJob(job, trigger);
        
        
        
        

下面的截图是Java源码给出的示例：

我们在使用Quartz时，一般的操作步骤为：

步骤1：自定义Job类（如：MyJob），实现Job接口；

步骤2：使用 JobBuilder生成JobDetail；

步骤3：定义Trigger类，一般使用TriggerBuilder生成；

步骤4：定义Scheduler类，并 Scheduler . scheduleJob(job, trigger);

步骤5： Scheduler.start();

步骤6：当需要关闭 Scheduler 时，使用 Scheduler. shutdown();

下面将具体进行讲解。

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二、Job、JobDetail、JobBuilder

官方定义：

1. Job - an interface to be implemented by components that you wish to have executed by the scheduler.
   
2. JobDetail - used to define instances of Jobs.
   
3. JobBuilder - used to define/build JobDetail instances, which define instances of Jobs.
   

Job

Job是一个接口类，下面是它的源码：

如果要实现自己的作业（任务），最简单的方式就是实现该接口，并实现接口中的execute()方法，当触发该作业时，就是执行execute()方法；

public class HelloJob implements Job {

    public HelloJob() {
    }

    public void execute(JobExecutionContext context)
      throws JobExecutionException
    {
      System.err.println("Hello!  HelloJob is executing.");
    }
  }

JobDetail 

JobDetail ：用于定义Job的实例，一般该类都是通过JobBuilder生成；

JobBuilder： 用于定义或创建JobDetail实例，使用了建造者模式；

JobDetail job = newJob(HelloJob.class)
      .withIdentity("myJob", "group1") // name "myJob", group "group1"
      .build();

      
      
      
      
 
       //带参数 
      
      
      
      
      
 
       JobDetail job = JobBuilder.newJob(clazz) 
      
      
      
      
      

                            .withIdentity(new JobKey(jobName, groupName)) 
      
      
      
      
      

                            .usingJobData(new JobDataMap(params)) 
      
      
      
      
      

                            .build(); 
      

从上面的接口类中我们可以知道，只要有了JobDetail的实现类，我们就可以获取到：

1. key;
2. JobClass；
3. JobDataMap；等

那我们在自定义的Job中怎么才能获取到JobDetail相关信息呢？？

由上面可知，当自定义的作业被触发时，我们可以通过JobExecutionContext获取到JobDetail，进而获取JobDataMap、JobKey、JobClass等等信息；

JobBuilder

这里JobBuilder使用了建造者模式，下面对其源码进行解析；

对于建造者模式，这里不进行详述，首先看下它的字段：

JobKey:作业的唯一标识，由name和group组成，如下：

jobClass：指定上述我们讲的自定义的Job（如：HelloJob ）；

JobDataMap：可以通过这个属性给自定义的Job（如：HelloJob）传递参数；

因为使用了建造者模式，所以实际创建的对象为：JobDetailImpl

JobDetailImpl类实现了JobDeteil接口，如下：

下图是类的层级结构图：

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三、Trigger、TriggerBuilder

官方定义：

Trigger - a component that defines the schedule upon which a given Job will be executed.

TriggerBuilder - used to define/build Trigger instances.

下面是触发器层次结构，常用的有SimpleTrigger、CronTrigger等；

SimpleTrigger

主要属性：

CronTrigger

使用CronTrigger可以进行很强大的控制，关于Cron表达式，下面的章节会介绍；

主要的参数：

TriggerBuilder

首先看下实现的例子：使用的也是建造者模式（建造者模式可自行搜索）；

TriggerBuilder的属性如下：

通过withIdentity方法设定trigger唯一标识：

通过方法withSchedule设置调度器：

从上面可以看出，这个方法传递进去的实际上是一个调度器Scheduler的Builder，真正的调度器Scheduler还是需要通过ScheduleBuilder去创建，这里使用的还是建造者模式，从下面的层次可以看出，已经实现了4种ScheduleBuilder，这里以SimplesCheduleBuilder进行分析，其他类似

下面我们看看SimplesCheduleBuilder的源码实现；

上面是build方法，可以看出，真正创建的是：SimpleTriggerImpl类，这个类在上面已经介绍过，它是Trigger的一个实现类；

我们接着看TriggerBuilder的build方法：

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四、Scheduler

官方定义：

Scheduler - the main API for interacting with the scheduler.

与调度程序交互的主要API。

主要的用法：

     
     
     
     

      
      
      
      
Scheduler  scheduler = StdSchedulerFactory.getDefaultScheduler();
      
      
      
      
scheduler.start();
      
      
      
      
scheduler.shutdown();
     
     
     
     

说明：

只有在scheduler.start();之后，trigger以及Job才能有效运行；

shutdown用于关闭；

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五、JobListener、SchedulerListener、TriggerListener

对监听进行注册：

      

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六、Cron表达式

语法格式：

示例：

• * ("all values") - used to select all values within a field. For example, "" in the minute field means *"every minute".

• ? ("no specific value") - useful when you need to specify something in one of the two fields in which the character is allowed, but not the other. For example, if I want my trigger to fire on a particular day of the month (say, the 10th), but don't care what day of the week that happens to be, I would put "10" in the day-of-month field, and "?" in the day-of-week field. See the examples below for clarification.

• - - used to specify ranges. For example, "10-12" in the hour field means "the hours 10, 11 and 12".

• , - used to specify additional values. For example, "MON,WED,FRI" in the day-of-week field means "the days Monday, Wednesday, and Friday".

• / - used to specify increments. For example, "0/15" in the seconds field means "the seconds 0, 15, 30, and 45". And "5/15" in the seconds field means "the seconds 5, 20, 35, and 50". You can also specify '/' after the '' character - in this case '' is equivalent to having '0' before the '/'. '1/3' in the day-of-month field means "fire every 3 days starting on the first day of the month".

• L ("last") - has different meaning in each of the two fields in which it is allowed. For example, the value "L" in the day-of-month field means "the last day of the month" - day 31 for January, day 28 for February on non-leap years. If used in the day-of-week field by itself, it simply means "7" or "SAT". But if used in the day-of-week field after another value, it means "the last xxx day of the month" - for example "6L" means "the last friday of the month". You can also specify an offset from the last day of the month, such as "L-3" which would mean the third-to-last day of the calendar month. When using the 'L' option, it is important not to specify lists, or ranges of values, as you'll get confusing/unexpected results.

• W ("weekday") - used to specify the weekday (Monday-Friday) nearest the given day. As an example, if you were to specify "15W" as the value for the day-of-month field, the meaning is: "the nearest weekday to the 15th of the month". So if the 15th is a Saturday, the trigger will fire on Friday the 14th. If the 15th is a Sunday, the trigger will fire on Monday the 16th. If the 15th is a Tuesday, then it will fire on Tuesday the 15th. However if you specify "1W" as the value for day-of-month, and the 1st is a Saturday, the trigger will fire on Monday the 3rd, as it will not 'jump' over the boundary of a month's days. The 'W' character can only be specified when the day-of-month is a single day, not a range or list of days.

The 'L' and 'W' characters can also be combined in the day-of-month field to yield 'LW', which translates to *"last weekday of the month"*.

• # - used to specify "the nth" XXX day of the month. For example, the value of "6#3" in the day-of-week field means"the third Friday of the month" (day 6 = Friday and "#3" = the 3rd one in the month). Other examples: "2#1" = the first Monday of the month and "4#5" = the fifth Wednesday of the month. Note that if you specify "#5" and there is not 5 of the given day-of-week in the month, then no firing will occur that month.

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七、参考链接

http://www.cnblogs.com/ssslinppp 

http://www.quartz-scheduler.org/

http://www.quartz-scheduler.org/documentation/quartz-2.1.x/tutorials/crontrigger 

来自为知笔记(Wiz)

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