SpringBoot学习－（十九）SpringBoot定时器#Schedule

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SpringBoot学习－（十九）SpringBoot定时器#Schedule

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：

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;

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。

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

配置Schedule

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 2017年10月16日 上午10:25:16 */ @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 2017年10月16日 上午10:07:03 */ @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.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.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 * * www.apache/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 Schedules */ @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 org.springframework.scheduling.support.CronSequenceGenerator */ 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 java.util.TimeZone */ 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 the delay in milliseconds */ 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 3.2.2 */ String fixedDelayString() default ""; /** * Execute the annotated method with a fixed period in milliseconds between * invocations. * @return the period in milliseconds */ 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 3.2.2 */ 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 3.2 */ 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 3.2.2 */ 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。

本文标签： 定时器SpringBootschedule