[TOC] # 1. 任務全局唯一 每個 JobDetail 都有一個唯一的身份，在全局中該 JobDetail 始終只能存在一個。 ```java JobDetail jobDetail = JobBuilder .newJob(AccountJob.class) //任務ID .withIdentity("job1", "job-group1") .build(); ``` 上面已經創建了 ID 為`job-group1.job1`的任務，如果再重新創建則拋出如下異常，阻止你再重新創建相同的任務。 ``` Unable to store Job : 'job-group1.job1', because one already exists with this identification. org.quartz.ObjectAlreadyExistsException: Unable to store Job : 'job-group1.job1', because one already exists with this identification. at org.quartz.simpl.RAMJobStore.storeJob(RAMJobStore.java:279) ``` >[info]觸發器雖然也有`withIdentity(name, group)`來設置該觸發器的 ID。但如果重復創建，則后創建的觸發器會覆蓋前面創建的觸發器，不會觸發異常。 <br/> # 2. 觸發器與任務的數量綁定關系 * 一個觸發器（Trigger）只能與一個任務（JobDetail）綁定。 * 一個任務（JobDetail）可以與多個觸發器（Trigger）綁定。 下面演示一個任務如何與多個觸發器綁定。 **1. 定時任務要執行的業務代碼** ```java @Slf4j public class UserJob extends QuartzJobBean { @Override protected void executeInternal(JobExecutionContext context) throws JobExecutionException { TriggerKey triggerKey = context.getTrigger().getKey(); JobKey jobKey = context.getJobDetail().getKey(); log.info("觸發器ID: {}", triggerKey.getGroup() + "." + triggerKey.getName()); log.info("任務ID: {}\n", jobKey.getGroup() + "." + jobKey.getName()); } } ``` <br/> **2. 一個任務綁定多個觸發器** ```java public void jobManyTrigger() throws SchedulerException { JobDetail jobDetail = JobBuilder.newJob(UserJob.class) .withIdentity("job4", "job-group1") .build(); Trigger trigger1 = TriggerBuilder.newTrigger() .withIdentity("trigger3", "trigger-group1") .startNow() .withSchedule(SimpleScheduleBuilder.simpleSchedule() .withIntervalInSeconds(4) .repeatForever() ) .build(); Trigger trigger2 = TriggerBuilder.newTrigger() .withIdentity("trigger4", "trigger-group1") //除了第一個觸發器，其余的觸發器用 forJob 綁定 job .forJob(jobDetail) .startNow() .withSchedule(SimpleScheduleBuilder.simpleSchedule() .withIntervalInSeconds(5) .repeatForever() ) .build(); Trigger trigger3 = TriggerBuilder.newTrigger() .withIdentity("trigger5", "trigger-group1") //除了第一個觸發器，其余的觸發器用 forJob 綁定 job .forJob(jobDetail) .startNow() .withSchedule(SimpleScheduleBuilder.simpleSchedule() .withIntervalInSeconds(6) .repeatForever() ) .build(); //第一個觸發器調用 scheduleJob(JobDetail, Trigger) 進行綁定任務 scheduler.scheduleJob(jobDetail, trigger1); //剩余的觸發器調用 scheduleJob(Trigger) 進行綁定，不能再調用 scheduleJob(JobDetail, Trigger) scheduler.scheduleJob(trigger2); scheduler.scheduleJob(trigger3); scheduler.start(); } ``` 啟動后日志打印如下： ``` //同一個任務可以由多個觸發器觸發 2023-03-31T18:07:05.36...job.UserJob : 觸發器ID: trigger-group1.trigger3 2023-03-31T18:07:05.36...job.UserJob : 任務ID: job-group1.job4 ... 2023-03-31T18:07:07.36...job.UserJob : 觸發器ID: trigger-group1.trigger4 2023-03-31T18:07:07.36...job.UserJob : 任務ID: job-group1.job4 ... 2023-03-31T18:07:09.36...job.UserJob : 觸發器ID: trigger-group1.trigger5 2023-03-31T18:07:09.36...job.UserJob : 任務ID: job-group1.job4 ```