在启动类上增加注解@EnableScheduling ( springboot2 不加也可以)
使用 ScheduledThreadPoolExecutor 执行定时任务  工作线程数默认1
任务执行抛出异常，下一次会继续执行
注意与  JDK ScheduledExecutorService 的区别  
JDK ScheduledExecutorService  任务抛出异常，任务不会再执行
 ScheduledThreadPoolExecutor使用介绍 



线程数配置
@Configuration
public class ScheduleConfig implements SchedulingConfigurer {

    @Override
    public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
        // 7个工作线程
        taskRegistrar.setScheduler(Executors.newScheduledThreadPool(7));
    }
}


任务不会重叠执行 ，只有执行完了 ， 才会触发下一次执行


pool-3-thread-3 TaskBean.task2() run 2020-06-30T07:50:36.776
pool-3-thread-1 TaskBean.task1() run 2020-06-30T07:50:37.005
pool-3-thread-5 TaskBean.task2() run 2020-06-30T07:50:38.778
pool-3-thread-1 TaskBean.task1() run 2020-06-30T07:50:40.003
pool-3-thread-5 TaskBean.task2() run 2020-06-30T07:50:40.782
pool-3-thread-5 TaskBean.task2() run 2020-06-30T07:50:42.786
pool-3-thread-6 TaskBean.task1() run 2020-06-30T07:50:43.003
pool-3-thread-2 TaskBean.task2() run 2020-06-30T07:50:44.788



@Component 
public class TaskBean {
	// 定时任务 
	
	private static final Random rand = new Random();
	
	@Scheduled(cron="* * * * * ?")
	public void task1(){	
	    // 模拟执行抛异常	
		if(rand.nextInt(10)%3 ==0){
			throw new RuntimeException("TaskBean.task1() run error,"+LocalDateTime.now());
		}
		
	    System.out.println(Thread.currentThread().getName() + " TaskBean.task1() run " + LocalDateTime.now());
	    try{
	        Thread.sleep(2000);
	    }catch(Throwable e){
	    	System.out.println("sleep error,"+e);
	    }
	}
	
	@Scheduled(fixedDelayString = "2000")
	  public void task2() {
	    System.out.println(Thread.currentThread().getName() + " TaskBean.task2() run " + LocalDateTime.now());
	  }

}



cron 每隔10秒执行一次
@Scheduled(cron = "0/10 * * * * *")
第0秒开始执行，方法执行了15秒，下一次执行时间第20秒
执行时间超过调度频率时，在下个周期执行


固定间隔
@Scheduled(fixedDelay = 1000*10) 
第0秒开始执行，方法执行了15秒，下一次执行时间 第25秒 

@Scheduled(initialDelay = 0, fixedDelay = 10*1000L)



固定频率 
@Scheduled(fixedRate = 1000*10)
第0秒开始执行，方法执行了15秒，下一次执行时间 第15秒
执行时间超过调度频率时，立即执行 下一次



2020-06-30 18:26:50 [pool-3-thread-6] ERROR org.springframework.scheduling.support.TaskUtils$LoggingErrorHandler TaskUtils.java 96 handleError -Unexpected error occurred in scheduled task.  
java.lang.RuntimeException: TaskBean.task1() run error,2020-06-30T18:26:50.003
	at demo.bean.TaskBean.task1(TaskBean.java:20)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:65)
	at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54)
	at org.springframework.scheduling.concurrent.ReschedulingRunnable.run(ReschedulingRunnable.java:93)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)



完整代码
https://gitee.com/dyyx/springboothello/blob/master/src/main/java/demo/bean/TaskBean.java



 ScheduledThreadPoolExecutor使用介绍 
 Timer和ScheduledExecutorService的区别  
 cron表达式实例