Java定时任务

Thread实现定时任务

public class TestDemo {
    private static int count = 0;
    public static void main(String[] args) {
        // 基于Thread实现定时任务
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                while (true) {
                    try {
                        // 每隔 1s 执行任务
                        Thread.sleep(1000);
                        System.out.println(“count: ” + count);
                        count ++;
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }
        };
        new Thread(runnable).start();
    }
}

TimeTask实现定时任务

private static int count = 0;
public static void timerTaskTest() {
    // 基于Thread实现定时任务
    TimerTask timerTask = new TimerTask() {
        @Override
        public void run() {
            System.out.println("count: " + count);
            count ++;
        }
    };
    // 定义触发规则
    Timer timer = new Timer();
    // 天数
    long delay = 0;
    // 秒数
    long period = 1000;
    timer.scheduleAtFixedRate(timerTask, delay, period);
}

线程池实现定时任务

private static int count = 0;
public static void threadSchedulerTest() {
    // 基于Thread实现定时任务
    Runnable runnable = new Runnable() {
        @Override
        public void run() {
            System.out.println("count: " + count);
            count ++;
        }
    };
    ScheduledExecutorService service = Executors.newSingleThreadScheduledExecutor();
    service.scheduleAtFixedRate(runnable, 1, 1, TimeUnit.SECONDS);
}

Quartz实现定时任务

引入依赖

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

编写任务

public class MyJob implements Job {
    public void execute(JobExecutionContext context) throws JobExecutionException {
        System.out.println("quartz MyJob date:" + new Date().getTime());
    }
}

编写调度器

public static void test4() throws Exception {
    //1.创建Scheduler的工厂
    SchedulerFactory sf = new StdSchedulerFactory();
    //2.从工厂中获取调度器实例
    Scheduler scheduler = sf.getScheduler();
    //3.创建JobDetail
    JobDetail jobDetail = JobBuilder.newJob(MyJob.class)
            .withDescription("this is a ram job") //job的描述
            .withIdentity("ramJob", "ramGroup") //job 的name和group
            .build();
    //任务运行的时间，SimpleSchedle类型触发器有效
    long time=  System.currentTimeMillis() + 3*1000L; //3秒后启动任务
    Date statTime = new Date(time);
    //4.创建Trigger
    //使用SimpleScheduleBuilder或者CronScheduleBuilder
    Trigger trigger = TriggerBuilder.newTrigger()
            .withDescription("")
            .withIdentity("ramTrigger", "ramTriggerGroup")
            //.withSchedule(SimpleScheduleBuilder.simpleSchedule())
            .startAt(statTime)  //默认当前时间启动
            .withSchedule(CronScheduleBuilder.cronSchedule("0/2 * * * * ?")) //两秒执行一次
            .build();
    //5.注册任务和定时器
    scheduler.scheduleJob(jobDetail, trigger);
    //6.启动 调度器
    scheduler.start();
}