Spring Scheduled定時任務動態修改cron參數

使用spring @scheduled注解可以方便的設定定時任務，但是對於定時參數需要變化的情況就會很不方便，如果要實現更改定時參數，就要停止服務，更改參數，重新部署。
對於這種需求， 可以利用TaskScheduler借口來實現,實現方法有兩種

• 啟動定時,關閉定時，使用新參數啟動定時
• 使用自定義的Trigger啟動定時，更改參數

范例代碼如下

package schedule;

import java.util.Date;

public class Say implements Runnable {
	
	@Override
	public void run(){
		System.out.println("" + new Date() + " hello");
	}
}

 

package schedule;

import java.util.Date;
import java.util.concurrent.ScheduledFuture;

import javax.annotation.PostConstruct;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.scheduling.Trigger;
import org.springframework.scheduling.TriggerContext;
import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
import org.springframework.scheduling.support.CronTrigger;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
@SpringBootApplication
public class ScheduleApplication {
	
	@Autowired
	private ThreadPoolTaskScheduler threadPoolTaskScheduler;
	
	@Bean
	public ThreadPoolTaskScheduler threadPoolTaskScheduler(){
		return new ThreadPoolTaskScheduler();
	}
	
	private ScheduledFuture<?> future;
	
	@RequestMapping("/")
	@ResponseBody
	public String home(){
		return "home";
	}
	
	///方法一
	
	@RequestMapping("/startCron")
	@ResponseBody
	public String startCron(){
		System.out.println("x0");
		//threadPoolTaskScheduler.shutdown();
		future = threadPoolTaskScheduler.schedule(new Say(), new CronTrigger("*/5 * * * * *"));
		System.out.println("x1");
		return "x";
	}
	
	@RequestMapping("/stopCron")
	@ResponseBody
	public String stopCron(){
		System.out.println("stop >>>>>");
		if(future != null) {
			future.cancel(true);
		}
		//future = threadPoolTaskScheduler.schedule(new Say(), new CronTrigger("*/5 * * * * *"));
		System.out.println("stop <<<<<");
		return "stop cron";
	}
	
	@RequestMapping("/startCron10")
	@ResponseBody
	public String startCron10(){
		System.out.println("x100");
		future = threadPoolTaskScheduler.schedule(new Say10(), new CronTrigger("*/12 * * * * *"));
		System.out.println("x101");
		return "x10";
	}

	
	///方法二
	
	private String cronStr = "*/5 * * * * *";
	@RequestMapping("/startCron1")
	@ResponseBody
	public String startCron1(){
		System.out.println("startCron1 >>>>");
		threadPoolTaskScheduler.schedule(new Say(), new Trigger(){
			@Override
			public Date nextExecutionTime(TriggerContext triggerContext){
				return new CronTrigger(cronStr).nextExecutionTime(triggerContext);
			}
		});
		System.out.println("startCron1 <<<<");
		return "*****";
	}
	
	
	@PostConstruct
	public void start(){
		startCron1();
	}
	
	@RequestMapping("/changeCronStr")
	@ResponseBody
	public String changeCronStr(){
		cronStr = "*/12 * * * * *";
		System.out.println("change "  + cronStr);
		return  cronStr;
	}
	
	@RequestMapping("/changeCronStr5")
	@ResponseBody
	public String changeCronStr5(){
		cronStr = "*/5 * * * * *";
		System.out.println("change "  + cronStr);
		return  cronStr;
	}
	
	
	public static void main(String[] args) {
		SpringApplication.run(ScheduleApplication.class, args);
	}
}

 說明 threadPoolTaskScheduler.shutdown();會拋出異常
@PostConstruct 在依賴注入完成后，進行調用
使用

{
    sartcron();
}

會產生空指針異常，以為依賴注入為完成.
@PostConstruct還可以使用BeanPostProcessor的功能來完成.
或使用

public class StartupListener implements ApplicationListener<ContextRefreshedEvent>

 

監聽事件.

參考
Spring/SpringMVC在啟動完成后執行方法
http://blog.csdn.net/renyisheng/article/details/50803875
Spring/SpringMVC在啟動完成后執行方法
http://www.cnblogs.com/itjcw/p/5977911.html
Spring @Scheduled定時任務動態修改cron參數
http://blog.csdn.net/xht555/article/details/53121962
Java 定時任務系列（2）-Spring 定時任務的幾種實現
https://segmentfault.com/a/1190000002504252
Java timer task schedule
http://stackoverflow.com/questions/4044729/java-timer-task-schedule
[Spring筆記]支持注解的Spring調度器

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