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SpringBoot学习－（十九）SpringBoot定时器#Schedule

时间：2022-10-11 17:00:47浏览次数：55  
标签：INFO 10 定时器 SpringBoot 17 Schedule 16 2017 logback


定时器概述

后台项目开发中经常会用到定时器，现在实现定时器的方式也是多种多样。下面列举几种常见的定时器实现方式：

  1. Quartz：Quartz的使用相当广泛，它是一个功能强大的调度器，当然使用起来也相对麻烦;
  2. java.util包里的Timer，它也可以实现定时任务但是功能过于单一所有使用很少。
  3. 就是我们今天要介绍的Spring自带的定时任务Schedule，其实可以把它看作是一个简化版的，轻量级的Quartz，使用起来也相对方便很多。

使用步骤

  1. 配置Schedule
  2. 书写定时器类

配置Schedule

package com.ahut.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.EnableScheduling;

/**
 * 
 * @ClassName: ScheduleConfig
 * @Description: 配置定时器
 * @author cheng
 * @date
@Configuration
@EnableScheduling
public class ScheduleConfig

书写定时器类

package com.ahut.schedule;

import java.text.MessageFormat;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

/**
 * 
 * @ClassName: ScheduledTasks
 * @Description: 自定义定时器任务
 * @author cheng
 * @date
@Component
public class ScheduledTasks

    // 日志
    private Logger log = LoggerFactory.getLogger(this.getClass());

    private int fixedDelayCount = 1;

    /**
     * 
     * @Title: testFixDelay
     * @Description:表示上一次任务执行完成后多久再次执行，参数类型为long，单位ms;
     */
    @Scheduled(fixedDelay = 5000)
    public void testFixDelay() {
        log.info(MessageFormat.format("fixedDelay()第{0}次执行", fixedDelayCount++));
    }

}

执行结果：

2017-10-16 17:07:36.911 logback [MessageBroker-1] INFO  com.ahut.schedule.ScheduledTasks - fixedDelay()第1次执行
2017-10-16 17:07:36.918 logback [restartedMain] INFO  o.a.coyote.http11.Http11NioProtocol - Initializing ProtocolHandler ["http-nio-8080"]
2017-10-16 17:07:36.940 logback [restartedMain] INFO  o.a.coyote.http11.Http11NioProtocol - Starting ProtocolHandler ["http-nio-8080"]
2017-10-16 17:07:36.963 logback [restartedMain] INFO  o.a.tomcat.util.net.NioSelectorPool - Using a shared selector for servlet write/read
2017-10-16 17:07:37.005 logback [restartedMain] INFO  o.s.b.c.e.t.TomcatEmbeddedServletContainer - Tomcat started on port(s): 8080 (http)
2017-10-16 17:07:37.034 logback [restartedMain] INFO  com.ahut.AhutApplication - Started AhutApplication in 8.228 seconds (JVM running for 9.71)
2017-10-16 17:07:41.912 logback [MessageBroker-2] INFO  com.ahut.schedule.ScheduledTasks - fixedDelay()第2次执行
2017-10-16 17:07:46.914 logback [MessageBroker-3] INFO  com.ahut.schedule.ScheduledTasks - fixedDelay()第3次执行
2017-10-16 17:07:51.915 logback [MessageBroker-3] INFO  com.ahut.schedule.ScheduledTasks - fixedDelay()第4次执行
2017-10-16 17:07:56.920 logback [MessageBroker-3] INFO  com.ahut.schedule.ScheduledTasks - fixedDelay()第5次执行
2017-10-16 17:08:01.923 logback [MessageBroker-3] INFO  com.ahut.schedule.ScheduledTasks - fixedDelay()第6次执行
2017-10-16 17:08:06.924 logback [MessageBroker-2] INFO  com.ahut.schedule.ScheduledTasks - fixedDelay()第7次执行
2017-10-16 17:08:11.926 logback [MessageBroker-2] INFO  com.ahut.schedule.ScheduledTasks - fixedDelay()第8次执行
2017-10-16 17:08:16.928 logback [MessageBroker-2] INFO  com.ahut.schedule.ScheduledTasks - fixedDelay()第9次执行
2017-10-16 17:08:21.928 logback [MessageBroker-2] INFO  com.ahut.schedule.ScheduledTasks - fixedDelay()第10次执行

方法：

private int fixedRateCount = 1;

    /**
     * 
     * @Title: testFixedRate
     * @Description:fixedRate = 5000表示当前方法开始执行5000ms后，Spring scheduling会再次调用该方法
     */
    @Scheduled(fixedRate = 5000)
    public void testFixedRate() {
        log.info(MessageFormat.format("fixedRate: 第{0}次执行方法", fixedRateCount++));
    }

执行结果：

2017-10-16 17:10:41.629 logback [MessageBroker-1] INFO  com.ahut.schedule.ScheduledTasks - fixedRate: 第1次执行方法
2017-10-16 17:10:41.636 logback [restartedMain] INFO  o.a.coyote.http11.Http11NioProtocol - Initializing ProtocolHandler ["http-nio-8080"]
2017-10-16 17:10:41.655 logback [restartedMain] INFO  o.a.coyote.http11.Http11NioProtocol - Starting ProtocolHandler ["http-nio-8080"]
2017-10-16 17:10:41.685 logback [restartedMain] INFO  o.a.tomcat.util.net.NioSelectorPool - Using a shared selector for servlet write/read
2017-10-16 17:10:41.720 logback [restartedMain] INFO  o.s.b.c.e.t.TomcatEmbeddedServletContainer - Tomcat started on port(s): 8080 (http)
2017-10-16 17:10:41.729 logback [restartedMain] INFO  com.ahut.AhutApplication - Started AhutApplication in 6.266 seconds (JVM running for 7.315)
2017-10-16 17:10:46.628 logback [MessageBroker-2] INFO  com.ahut.schedule.ScheduledTasks - fixedRate: 第2次执行方法
2017-10-16 17:10:51.629 logback [MessageBroker-3] INFO  com.ahut.schedule.ScheduledTasks - fixedRate: 第3次执行方法
2017-10-16 17:10:56.629 logback [MessageBroker-2] INFO  com.ahut.schedule.ScheduledTasks - fixedRate: 第4次执行方法
2017-10-16 17:11:01.629 logback [MessageBroker-2] INFO  com.ahut.schedule.ScheduledTasks - fixedRate: 第5次执行方法
2017-10-16 17:11:06.630 logback [MessageBroker-4] INFO  com.ahut.schedule.ScheduledTasks - fixedRate: 第6次执行方法
2017-10-16 17:11:11.631 logback [MessageBroker-3] INFO  com.ahut.schedule.ScheduledTasks - fixedRate: 第7次执行方法
2017-10-16 17:11:16.630 logback [MessageBroker-3] INFO  com.ahut.schedule.ScheduledTasks - fixedRate: 第8次执行方法
2017-10-16 17:11:21.631 logback [MessageBroker-3] INFO  com.ahut.schedule.ScheduledTasks - fixedRate: 第9次执行方法

方法：

private int initialDelayCount = 1;

    /**
     * 
     * @Title: testInitialDelay
     * @Description:initialDelay =1000表示延迟1000ms执行第一次任务
     */
    @Scheduled(initialDelay = 1000, fixedRate = 5000)
    public void testInitialDelay() {
        log.info(MessageFormat.format("initialDelay: 第{0}次执行方法", initialDelayCount++));
    }

执行结果：

2017-10-16 17:44:11.217 logback [MessageBroker-1] INFO  com.ahut.schedule.ScheduledTasks - initialDelay: 第1次执行方法
2017-10-16 17:44:16.216 logback [MessageBroker-2] INFO  com.ahut.schedule.ScheduledTasks - initialDelay: 第2次执行方法
2017-10-16 17:44:21.217 logback [MessageBroker-3] INFO  com.ahut.schedule.ScheduledTasks - initialDelay: 第3次执行方法
2017-10-16 17:44:26.217 logback [MessageBroker-3] INFO  com.ahut.schedule.ScheduledTasks - initialDelay: 第4次执行方法
2017-10-16 17:44:31.217 logback [MessageBroker-3] INFO  com.ahut.schedule.ScheduledTasks - initialDelay: 第5次执行方法

方法：

private int cronCount = 1;

    /**
     * 
     * @Title: testCron
     * @Description:cron接受cron表达式，根据cron表达式确定定时规则
     */
    @Scheduled(cron = "*/6 * * * * ?")
    public void testCron() {
        log.info(MessageFormat.format("core: 第{0}次执行方法", cronCount++));
    }

执行结果：

2017-10-16 17:47:06.009 logback [MessageBroker-1] INFO  com.ahut.schedule.ScheduledTasks - core: 第1次执行方法
2017-10-16 17:47:12.007 logback [MessageBroker-2] INFO  com.ahut.schedule.ScheduledTasks - core: 第2次执行方法
2017-10-16 17:47:18.001 logback [MessageBroker-3] INFO  com.ahut.schedule.ScheduledTasks - core: 第3次执行方法
2017-10-16 17:47:24.001 logback [MessageBroker-2] INFO  com.ahut.schedule.ScheduledTasks - core: 第4次执行方法
2017-10-16 17:47:30.002 logback [MessageBroker-2] INFO  com.ahut.schedule.ScheduledTasks - core: 第5次执行方法

分析

@Scheduled 注解源码如下

/*
 * Copyright 2002-2016 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.scheduling.annotation;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Repeatable;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * An annotation that marks a method to be scheduled. Exactly one of
 * the {@link #cron()}, {@link #fixedDelay()}, or {@link #fixedRate()}
 * attributes must be specified.
 *
 * <p>The annotated method must expect no arguments. It will typically have
 * a {@code void} return type; if not, the returned value will be ignored
 * when called through the scheduler.
 *
 * <p>Processing of {@code @Scheduled} annotations is performed by
 * registering a {@link ScheduledAnnotationBeanPostProcessor}. This can be
 * done manually or, more conveniently, through the {@code <task:annotation-driven/>}
 * element or @{@link EnableScheduling} annotation.
 *
 * <p>This annotation may be used as a <em>meta-annotation</em> to create custom
 * <em>composed annotations</em> with attribute overrides.
 *
 * @author Mark Fisher
 * @author Dave Syer
 * @author Chris Beams
 * @since 3.0
 * @see EnableScheduling
 * @see ScheduledAnnotationBeanPostProcessor
 * @see
@Target({ElementType.METHOD, ElementType.ANNOTATION_TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Repeatable(Schedules.class)
public @interface Scheduled {

    /**
     * A cron-like expression, extending the usual UN*X definition to include
     * triggers on the second as well as minute, hour, day of month, month
     * and day of week.  e.g. {@code "0 * * * * MON-FRI"} means once per minute on
     * weekdays (at the top of the minute - the 0th second).
     * @return an expression that can be parsed to a cron schedule
     * @see
    String cron() default "";

    /**
     * A time zone for which the cron expression will be resolved. By default, this
     * attribute is the empty String (i.e. the server's local time zone will be used).
     * @return a zone id accepted by {@link java.util.TimeZone#getTimeZone(String)},
     * or an empty String to indicate the server's default time zone
     * @since 4.0
     * @see org.springframework.scheduling.support.CronTrigger#CronTrigger(String, java.util.TimeZone)
     * @see
    String zone() default "";

    /**
     * Execute the annotated method with a fixed period in milliseconds between the
     * end of the last invocation and the start of the next.
     * @return
    long fixedDelay() default -1;

    /**
     * Execute the annotated method with a fixed period in milliseconds between the
     * end of the last invocation and the start of the next.
     * @return the delay in milliseconds as a String value, e.g. a placeholder
     * @since
    String fixedDelayString() default "";

    /**
     * Execute the annotated method with a fixed period in milliseconds between
     * invocations.
     * @return
    long fixedRate() default -1;

    /**
     * Execute the annotated method with a fixed period in milliseconds between
     * invocations.
     * @return the period in milliseconds as a String value, e.g. a placeholder
     * @since
    String fixedRateString() default "";

    /**
     * Number of milliseconds to delay before the first execution of a
     * {@link #fixedRate()} or {@link #fixedDelay()} task.
     * @return the initial delay in milliseconds
     * @since
    long initialDelay() default -1;

    /**
     * Number of milliseconds to delay before the first execution of a
     * {@link #fixedRate()} or {@link #fixedDelay()} task.
     * @return the initial delay in milliseconds as a String value, e.g. a placeholder
     * @since
    String initialDelayString() default "";

}
  • cron：cron表达式，指定任务在特定时间执行;
  • fixedDelay：表示上一次任务执行完成后多久再次执行，参数类型为long，单位ms;
  • fixedDelayString：与fixedDelay含义一样，只是参数类型变为String;
  • fixedRate：表示按一定的频率执行任务，参数类型为long，单位ms;
  • fixedRateString: 与fixedRate的含义一样，只是将参数类型变为String;
  • initialDelay：表示延迟多久再第一次执行任务，参数类型为long，单位ms;
  • initialDelayString：与initialDelay的含义一样，只是将参数类型变为String;
  • zone：时区，默认为当前时区，一般没有用到。


标签：INFO,10,定时器,SpringBoot,17,Schedule,16,2017,logback
From： https://blog.51cto.com/u_15824687/5747163

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