Spring Scheduled定时任务动态修改cron参数

使用spring @scheduled注解可以方便的设定定时任务，但是对于定时参数需要变化的情况就会很不方便，如果要实现更改定时参数，就要停止服务，更改参数，重新部署。
对于这种需求， 可以利用TaskScheduler借口来实现,实现方法有两种

• 启动定时,关闭定时，使用新参数启动定时
• 使用自定义的Trigger启动定时，更改参数

范例代码如下

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@SpringBootApplicationpublic 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);    }}

说明 threadPoolTaskScheduler.shutdown();会抛出异常
@PostConstruct 在依赖注入完成后，进行调用
使用

{    sartcron();}

会产生空指针异常，以为依赖注入为完成.
@PostConstruct还可以使用BeanPostProcessor的功能来完成.
或使用

public class StartupListener implements ApplicationListener<ContextRefreshedEvent>

监听事件.

参考
Spring/SpringMVC在启动完成后执行方法
http://blog.csdn.net/renyisheng/article/details/50803875
Spring/SpringMVC在启动完成后执行方法
http://www.cnblogs.com/itjcw/p/5977911.html
Spring @Scheduled定时任务动态修改cron参数
http://blog.csdn.net/xht555/article/details/53121962
Java 定时任务系列（2）-Spring 定时任务的几种实现
https://segmentfault.com/a/1190000002504252
java timer task schedule
http://stackoverflow.com/questions/4044729/java-timer-task-schedule
[Spring笔记]支持注解的Spring调度器
http://www.w2bc.com/article/169011