2016 May 25 Java

Java 定时任务

Timer 和 TimerTask

Timer类可以调度任务，TimerTask则是通过在run()方法里实现具体任务。 Timer实例可以调度多任务，它是线程安全的。

public static void main(String args[]){
    new Timer(false).scheduleAtFixedRate(new TimerTask() {
        @Override
        public void run() {
            System.out.println("do something...");
        }
    },0,500);
}

ScheduledExecutorService

相比于Timer的单线程，ScheduledExecutorService通过线程池的方式来执行任务,是目前原生Java 实现任务定时的最佳方式

public static void main(String args[]){
   Runnable runnable = new Runnable() {
       public void run() {
           System.out.print("do something...");
       }
   };
    ScheduledExecutorService scheduledExecutorService = Executors.newSingleThreadScheduledExecutor();
    scheduledExecutorService.scheduleAtFixedRate(runnable,0,1,TimeUnit.SECONDS);
}

squartz

官网：http://www.quartz-scheduler.org/

Maven库

  <dependency>
      <groupId>org.quartz-scheduler</groupId>
      <artifactId>quartz</artifactId>
      <version>2.2.1</version>
  </dependency>

初始化和启动 Scheduler

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

实现任务逻辑

public class MyJob implements org.quartz.Job {
  public MyJob() {
  }
  public void execute(JobExecutionContext context) throws JobExecutionException {
      System.err.println("Hello World!  MyJob is executing.");
  }
}

设置 JobDetail 和 Trigger

// define the job and tie it to our MyJob class
JobDetail job = newJob(MyJob.class)
  .withIdentity("job1", "group1")
  .build();
// Trigger the job to run now, and then repeat every 40 seconds
Trigger trigger = newTrigger()
  .withIdentity("trigger1", "group1")
  .startNow()
  .withSchedule(simpleSchedule()
          .withIntervalInSeconds(40)
          .repeatForever())
  .build();
// Tell quartz to schedule the job using our trigger
scheduler.scheduleJob(job, trigger);