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316 lines
12 KiB
316 lines
12 KiB
# Spring 定时任务
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- Author: [HuiFer](https://github.com/huifer)
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- 源码阅读仓库: [SourceHot-spring](https://github.com/SourceHot/spring-framework-read)
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## EnableScheduling
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- 首先关注的类为启动定时任务的注解`@EnableScheduling`
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```java
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@Target(ElementType.TYPE)
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@Retention(RetentionPolicy.RUNTIME)
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@Import(SchedulingConfiguration.class)
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@Documented
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public @interface EnableScheduling {
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}
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```
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## SchedulingConfiguration
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- 注册定时任务相关信息
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```java
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@Configuration
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@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
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public class SchedulingConfiguration {
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/**
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* 开启定时任务
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* @return
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*/
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@Bean(name = TaskManagementConfigUtils.SCHEDULED_ANNOTATION_PROCESSOR_BEAN_NAME)
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@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
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public ScheduledAnnotationBeanPostProcessor scheduledAnnotationProcessor() {
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// 注册 ScheduledAnnotationBeanPostProcessor
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return new ScheduledAnnotationBeanPostProcessor();
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}
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}
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```
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## ScheduledAnnotationBeanPostProcessor
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- 关注 application 事件,以及 spring 生命周期相关的接口实现
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```java
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/**
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* application 事件
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* @param event the event to respond to
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*/
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@Override
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public void onApplicationEvent(ContextRefreshedEvent event) {
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if (event.getApplicationContext() == this.applicationContext) {
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// Running in an ApplicationContext -> register tasks this late...
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// giving other ContextRefreshedEvent listeners a chance to perform
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// their work at the same time (e.g. Spring Batch's job registration).
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// 注册定时任务
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finishRegistration();
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}
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}
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```
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```java
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@Override
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public Object postProcessAfterInitialization(Object bean, String beanName) {
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if (bean instanceof AopInfrastructureBean || bean instanceof TaskScheduler ||
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bean instanceof ScheduledExecutorService) {
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// Ignore AOP infrastructure such as scoped proxies.
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return bean;
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}
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// 当前类
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Class<?> targetClass = AopProxyUtils.ultimateTargetClass(bean);
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if (!this.nonAnnotatedClasses.contains(targetClass)) {
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// 方法扫描,存在 Scheduled、Schedules 注解的全部扫描
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Map<Method, Set<Scheduled>> annotatedMethods = MethodIntrospector.selectMethods(targetClass,
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(MethodIntrospector.MetadataLookup<Set<Scheduled>>) method -> {
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Set<Scheduled> scheduledMethods = AnnotatedElementUtils.getMergedRepeatableAnnotations(
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method, Scheduled.class, Schedules.class);
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return (!scheduledMethods.isEmpty() ? scheduledMethods : null);
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});
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if (annotatedMethods.isEmpty()) {
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this.nonAnnotatedClasses.add(targetClass);
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if (logger.isTraceEnabled()) {
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logger.trace("No @Scheduled annotations found on bean class: " + targetClass);
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}
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}
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else {
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// Non-empty set of methods
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annotatedMethods.forEach((method, scheduledMethods) ->
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// 处理 scheduled 相关信息
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scheduledMethods.forEach(scheduled -> processScheduled(scheduled, method, bean)));
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if (logger.isTraceEnabled()) {
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logger.trace(annotatedMethods.size() + " @Scheduled methods processed on bean '" + beanName +
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"': " + annotatedMethods);
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}
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}
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}
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return bean;
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}
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```
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- 处理定时任务注解
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```java
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protected void processScheduled(Scheduled scheduled, Method method, Object bean) {
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try {
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Runnable runnable = createRunnable(bean, method);
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boolean processedSchedule = false;
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String errorMessage =
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"Exactly one of the 'cron', 'fixedDelay(String)', or 'fixedRate(String)' attributes is required";
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Set<ScheduledTask> tasks = new LinkedHashSet<>(4);
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// Determine initial delay
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// 是否延迟执行
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long initialDelay = scheduled.initialDelay();
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// 延迟执行时间
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String initialDelayString = scheduled.initialDelayString();
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// 是否有延迟执行的时间
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if (StringUtils.hasText(initialDelayString)) {
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Assert.isTrue(initialDelay < 0, "Specify 'initialDelay' or 'initialDelayString', not both");
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if (this.embeddedValueResolver != null) {
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initialDelayString = this.embeddedValueResolver.resolveStringValue(initialDelayString);
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}
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if (StringUtils.hasLength(initialDelayString)) {
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try {
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initialDelay = parseDelayAsLong(initialDelayString);
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}
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catch (RuntimeException ex) {
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throw new IllegalArgumentException(
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"Invalid initialDelayString value \"" + initialDelayString + "\" - cannot parse into long");
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}
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}
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}
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// Check cron expression
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// 获取cron表达式
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String cron = scheduled.cron();
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// cron表达式是否存在
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if (StringUtils.hasText(cron)) {
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// 获取时区
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String zone = scheduled.zone();
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if (this.embeddedValueResolver != null) {
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// 字符串转换
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cron = this.embeddedValueResolver.resolveStringValue(cron);
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zone = this.embeddedValueResolver.resolveStringValue(zone);
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}
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if (StringUtils.hasLength(cron)) {
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// cron 是否延迟
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Assert.isTrue(initialDelay == -1, "'initialDelay' not supported for cron triggers");
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processedSchedule = true;
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if (!Scheduled.CRON_DISABLED.equals(cron)) {
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TimeZone timeZone;
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if (StringUtils.hasText(zone)) {
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// 时区解析
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timeZone = StringUtils.parseTimeZoneString(zone);
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}
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else {
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// 默认时区获取
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timeZone = TimeZone.getDefault();
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}
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// 创建任务
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tasks.add(this.registrar.scheduleCronTask(new CronTask(runnable, new CronTrigger(cron, timeZone))));
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}
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}
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}
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// At this point we don't need to differentiate between initial delay set or not anymore
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if (initialDelay < 0) {
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initialDelay = 0;
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}
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// Check fixed delay
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// 获取间隔调用时间
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long fixedDelay = scheduled.fixedDelay();
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// 间隔时间>0
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if (fixedDelay >= 0) {
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Assert.isTrue(!processedSchedule, errorMessage);
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processedSchedule = true;
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// 创建任务,间隔时间定时任务
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tasks.add(this.registrar.scheduleFixedDelayTask(new FixedDelayTask(runnable, fixedDelay, initialDelay)));
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}
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// 延迟时间
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String fixedDelayString = scheduled.fixedDelayString();
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if (StringUtils.hasText(fixedDelayString)) {
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if (this.embeddedValueResolver != null) {
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fixedDelayString = this.embeddedValueResolver.resolveStringValue(fixedDelayString);
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}
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if (StringUtils.hasLength(fixedDelayString)) {
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Assert.isTrue(!processedSchedule, errorMessage);
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processedSchedule = true;
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try {
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fixedDelay = parseDelayAsLong(fixedDelayString);
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}
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catch (RuntimeException ex) {
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throw new IllegalArgumentException(
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"Invalid fixedDelayString value \"" + fixedDelayString + "\" - cannot parse into long");
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}
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// 创建延迟时间任务
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tasks.add(this.registrar.scheduleFixedDelayTask(new FixedDelayTask(runnable, fixedDelay, initialDelay)));
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}
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}
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// Check fixed rate
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// 获取调用频率
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long fixedRate = scheduled.fixedRate();
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if (fixedRate >= 0) {
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Assert.isTrue(!processedSchedule, errorMessage);
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processedSchedule = true;
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// 创建调用频率的定时任务
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tasks.add(this.registrar.scheduleFixedRateTask(new FixedRateTask(runnable, fixedRate, initialDelay)));
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}
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String fixedRateString = scheduled.fixedRateString();
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if (StringUtils.hasText(fixedRateString)) {
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if (this.embeddedValueResolver != null) {
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fixedRateString = this.embeddedValueResolver.resolveStringValue(fixedRateString);
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}
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if (StringUtils.hasLength(fixedRateString)) {
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Assert.isTrue(!processedSchedule, errorMessage);
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processedSchedule = true;
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try {
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fixedRate = parseDelayAsLong(fixedRateString);
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}
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catch (RuntimeException ex) {
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throw new IllegalArgumentException(
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"Invalid fixedRateString value \"" + fixedRateString + "\" - cannot parse into long");
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}
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tasks.add(this.registrar.scheduleFixedRateTask(new FixedRateTask(runnable, fixedRate, initialDelay)));
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}
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}
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// Check whether we had any attribute set
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Assert.isTrue(processedSchedule, errorMessage);
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// Finally register the scheduled tasks
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synchronized (this.scheduledTasks) {
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// 定时任务注册
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Set<ScheduledTask> regTasks = this.scheduledTasks.computeIfAbsent(bean, key -> new LinkedHashSet<>(4));
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regTasks.addAll(tasks);
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}
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}
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catch (IllegalArgumentException ex) {
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throw new IllegalStateException(
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"Encountered invalid @Scheduled method '" + method.getName() + "': " + ex.getMessage());
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}
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}
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```
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## 定时任务
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- CronTask
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- cron 定时任务
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- FixedDelayTask
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- 间隔时间的定时任务
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- FixedRateTask
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- 调用频率的定时任务
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- ScheduledTask
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- 定时任务对象
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### cron 表达式解析
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- `org.springframework.scheduling.support.CronSequenceGenerator.doParse`
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```java
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private void doParse(String[] fields) {
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setNumberHits(this.seconds, fields[0], 0, 60);
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setNumberHits(this.minutes, fields[1], 0, 60);
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setNumberHits(this.hours, fields[2], 0, 24);
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setDaysOfMonth(this.daysOfMonth, fields[3]);
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setMonths(this.months, fields[4]);
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setDays(this.daysOfWeek, replaceOrdinals(fields[5], "SUN,MON,TUE,WED,THU,FRI,SAT"), 8);
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if (this.daysOfWeek.get(7)) {
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// Sunday can be represented as 0 or 7
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this.daysOfWeek.set(0);
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this.daysOfWeek.clear(7);
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}
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}
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```
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### 执行定时任务
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- 这里以 CronTask 任务进行分析,其他定时任务同理
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- `org.springframework.scheduling.config.ScheduledTaskRegistrar.scheduleCronTask`
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```java
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@Nullable
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public ScheduledTask scheduleCronTask(CronTask task) {
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// 从未执行的任务列表中删除,并且获取这个任务
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ScheduledTask scheduledTask = this.unresolvedTasks.remove(task);
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boolean newTask = false;
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// 没有这个任务
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if (scheduledTask == null) {
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scheduledTask = new ScheduledTask(task);
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newTask = true;
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}
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// 任务调度器是否为空
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if (this.taskScheduler != null) {
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scheduledTask.future = this.taskScheduler.schedule(task.getRunnable(), task.getTrigger());
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}
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else {
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// 添加到cron任务列表
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addCronTask(task);
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// 保存到没有执行的任务中
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this.unresolvedTasks.put(task, scheduledTask);
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}
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return (newTask ? scheduledTask : null);
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}
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```
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