一、这个是利用jdk自带的Thread类的sleep方法实现定时执行任务。
package tasker; import java.util.Date; public class tasker01 extends Thread { private static Date date; public static void main(String[] args) { while (true) { try { Thread.sleep((int) (Math.random() * 1000)); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println("休眠一秒"); date = new Date(); System.out.println(date); // 定时执行任务 } } }
二、利用 Java 自带的定时器任务执行类 java.util.Timer 和 java.util.TimerTask ,实现方式有两种,一种是用java匿名内部类实现,只需一个类即可,关于匿名内部类请参考,使用匿名内部类还有个前提条件:必须继承一个父类或实现一个接口。
package tasker; import java.util.Date; import java.util.Timer; public class tasker02 { public static void main(String[] args) { Timer timer = new Timer(); timer.schedule(task, 5000, 2000); } static java.util.TimerTask task = new java.util.TimerTask() { @Override public void run() { System.out.println("i am running"); Date date = new Date(); System.out.println(date); } }; }
第二种方式是新建一个类去继承TimerTask类,需要用两个类解决
Tasker类
package tasker; import java.util.Date; import java.util.TimerTask; public class Tasker extends TimerTask{ @Override public void run() { System.out.println("i am running"); Date date=new Date(); System.out.println(date); } }
main方法类
package tasker; import java.util.Timer; public class tasker02 { public static void main(String[] args) { Timer timer = new Timer(); timer.schedule(new Tasker(), 5000, 2000); } }
再举个例子
package timer; import java.util.Timer; import java.util.TimerTask; public class TestTimer { public static void main(String[] args) { System.out.println("About to schedule task."); new Reminder(10); System.out.println("Task scheduled..."); Timer timer=new Timer(); timer.schedule(new TaskTimer(), 3000); } public static class Reminder{ Timer timer; public Reminder(int sec){ timer = new Timer(); timer.schedule(new TimerTask(){ public void run(){ System.out.println("Time's up..."); timer.cancel(); } }, sec*1000); } } }
package timer; import java.util.TimerTask; public class TaskTimer extends TimerTask{ @Override public void run() { int m=4; if(m==4){ System.out.println("===="); }else{ System.out.println("定时器运行....."); } } }
三、使用ScheduledExecutorService类,此类改进了简陋的Timer类,Java提供的Time类可以周期性地或者延期执行任务,但是有时我们需要并行执行同样的任务,这个时候如果创建多个Time对象会给系统带来负担,解决办法是将定时任务放到线程池中执行。Java的ScheduledThreadPoolExecutor类实现了ScheduledExecutorService接口中定义的以不同方法执行任务的方法。
。
package tasker; import java.util.Date; import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; public class tasker03 { public static void main(String[] args) throws InterruptedException { ScheduledExecutorService scheduledThreadPool = Executors.newScheduledThreadPool(5); System.out.println("Current Time = " + new Date()); for (int i = 0; i < 3; i++) { Thread.sleep(1000); scheduledThreadPool.scheduleWithFixedDelay(task, 10000,2000, TimeUnit.SECONDS); } Thread.sleep(30000); scheduledThreadPool.shutdown(); while (!scheduledThreadPool.isTerminated()) { } System.out.println("Finished all threads"); } static java.util.TimerTask task = new java.util.TimerTask() { @Override public void run() { System.out.println("i am running"); Date date = new Date(); System.out.println(date); } }; }
改进版的和多线程有关的定时器,有两个类
WorkerThread类
package tasker; import java.util.Date; public class WorkerThread implements Runnable { private String command; public WorkerThread(){}; public WorkerThread(String command){ this.command=command; } @Override public void run() { System.out.println(Thread.currentThread().getName()+"start time:"+new Date()); processCommand(); System.out.println(Thread.currentThread().getName()+"end time:"+new Date()); } private void processCommand(){ try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } public String toString(){ return this.command; } }
main类
package tasker; import java.util.Date; import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; public class tasker03 { public static void main(String[] args) throws InterruptedException { ScheduledExecutorService scheduledThreadPool = Executors.newScheduledThreadPool(5); System.out.println("Current Time = " + new Date()); for (int i = 0; i < 3; i++) { Thread.sleep(1000); WorkerThread task=new WorkerThread("do something"); scheduledThreadPool.scheduleWithFixedDelay(task, 10000,2000, TimeUnit.SECONDS); } Thread.sleep(30000); scheduledThreadPool.shutdown(); while (!scheduledThreadPool.isTerminated()) { } System.out.println("Finished all threads"); } }
四、使用任务调度框架Quartz,官网 http://www.quartz-scheduler.org
在Spring中的用法:
引入jar包
java代码
package com.coalmine.desktop; import java.text.SimpleDateFormat; import java.util.Date; public class QuartzJob { public void work() { SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); Date date = new Date(); System.out.println(sdf.format(date) + " 执行Quartz定时器"); } }
applicationContext.xml配置如下:
<!-- 要调用的工作类 --> <bean id="quartzJob" class="com.coalmine.desktop.QuartzJob"></bean> <!-- 定义调用对象和调用对象的方法 --> <bean id="jobtask" class="org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean"> <!-- 调用的类 --> <property name="targetObject"> <ref bean="quartzJob" /> </property> <!-- 调用类中的方法 --> <property name="targetMethod"> <value>work</value> </property> </bean> <!-- 定义触发时间 --> <bean id="doTime" class="org.springframework.scheduling.quartz.CronTriggerBean"> <property name="jobDetail"> <ref bean="jobtask" /> </property> <!-- cron表达式 --> <property name="cronExpression"> <!-- 第 10秒 隔 5秒执行一次--> <value>10/5 * * * * ?</value> </property> </bean> <!-- 总管理类 如果将lazy-init='false'那么容器启动就会执行调度程序 --> <bean id="startQuertz" lazy-init="false" autowire="no" class="org.springframework.scheduling.quartz.SchedulerFactoryBean"> <property name="triggers"> <list> <ref bean="doTime" /> </list> </property> </bean>
启动服务后从第10秒开始每隔5秒执行一次work方法
参考文档:http://www.quartz-scheduler.org/generated/2.2.2/pdf/Quartz_Scheduler_Developer_Guide.pdf
首先创建要执行的类。
然后初始化Scheduler,
SchedulerFactory schedFact = new org.quartz.impl.StdSchedulerFactory();
Scheduler sched = schedFact.getScheduler();
sched.start();
创建job
JobDetail job = newJob(HelloJob.class).withIdentity("myJob", "group1").build();
创建任务执行触发器
Trigger trigger = newTrigger().withIdentity("myTrigger", "group1").startNow()
.withSchedule(simpleSchedule()
.withIntervalInSeconds(40)
.repeatForever())
.build();
安排工作
// Tell quartz to schedule the job using our trigger
sched.scheduleJob(job, trigger);
关闭计划
sched.shutdown(true);
============================================================
The key interfaces of the Quar API are:
Scheduler - the main API for interacting with the Scheduler.
Job - an interface to be implemented by components that you want the Scheduler to execute.
JobDetail - used to define instances of Jobs.
Trigger - a component that defines the schedule upon which a given Job will be executed.
JobBuilder - used to define/build JobDetail instances, which define instances of Jobs.
TriggerBuilder - used to define/build Trigger instances.