上一篇文章中,我们介绍了@scheduled
注解的使用,添加上就可以使用定时任务了
本篇文章,简单解析一下它的源码,看看是如何工作的,怎么就能跑起定时任务
首当其冲的就是这个注解,在开启定时任务第一步就是这个
package org.springframework.scheduling.annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.util.concurrent.Executor;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.scheduling.Trigger;
import org.springframework.scheduling.config.ScheduledTaskRegistrar;
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Import(SchedulingConfiguration.class)
@Documented
public @interface EnableScheduling {
}
注释我没有贴出来,其中有一点很感兴趣,就是线程池。看看昨天的定时任务启动,它的线程名长这样,scheduling
但这边,它可以允许我们手动指定一个线程池,代码如下
package com.banmoon.config;
import cn.hutool.core.thread.ThreadUtil;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.SchedulingConfigurer;
import org.springframework.scheduling.config.ScheduledTaskRegistrar;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
/**
* @author banmoon
* @date 2024/07/24 11:10:28
*/
@Configuration
public class ScheduingConfig implements SchedulingConfigurer {
@Override
public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
taskRegistrar.setScheduler(taskExecutor());
}
@Bean(destroyMethod = "shutdown")
public Executor taskExecutor() {
return Executors.newScheduledThreadPool(100, ThreadUtil.newNamedThreadFactory("定时任务", true));
}
}
运行查看结果,线程名字已改
请注意,这个注解上有个@Import(SchedulingConfiguration.class)
那么下一个类,便是SchedulingConfiguration.java
了
至于
@Import
使用它,可以将指定的类进行导入,使得另一个配置类中定义的bean
可以被当前配置类中的bean
使用
好的,先看源码
package org.springframework.scheduling.annotation;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Role;
import org.springframework.scheduling.config.TaskManagementConfigUtils;
@Configuration(proxyBeanMethods = false)
@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
public class SchedulingConfiguration {
@Bean(name = TaskManagementConfigUtils.SCHEDULED_ANNOTATION_PROCESSOR_BEAN_NAME)
@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
public ScheduledAnnotationBeanPostProcessor scheduledAnnotationProcessor() {
return new ScheduledAnnotationBeanPostProcessor();
}
}
这个类没什么好说 的,创建了ScheduledAnnotationBeanPostProcessor.java
的bean
这个类的源码就不全贴了,我们关注主要的几个方法
这个类实现了BeanPostProcessor.java
这个接口,想必大家都知道这个是干什么的了吧
public class ScheduledAnnotationBeanPostProcessor
implements ScheduledTaskHolder, MergedBeanDefinitionPostProcessor, DestructionAwareBeanPostProcessor,
Ordered, EmbeddedValueResolverAware, BeanNameAware, BeanFactoryAware, ApplicationContextAware,
SmartInitializingSingleton, ApplicationListener<ContextRefreshedEvent>, DisposableBean {
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) {
if (bean instanceof AopInfrastructureBean || bean instanceof TaskScheduler ||
bean instanceof ScheduledExecutorService) {
// Ignore AOP infrastructure such as scoped proxies.
return bean;
}
Class<?> targetClass = AopProxyUtils.ultimateTargetClass(bean);
if (!this.nonAnnotatedClasses.contains(targetClass) &&
AnnotationUtils.isCandidateClass(targetClass, Arrays.asList(Scheduled.class, Schedules.class))) {
Map<Method, Set<Scheduled>> annotatedMethods = MethodIntrospector.selectMethods(targetClass,
(MethodIntrospector.MetadataLookup<Set<Scheduled>>) method -> {
Set<Scheduled> scheduledAnnotations = AnnotatedElementUtils.getMergedRepeatableAnnotations(
method, Scheduled.class, Schedules.class);
return (!scheduledAnnotations.isEmpty() ? scheduledAnnotations : null);
});
if (annotatedMethods.isEmpty()) {
this.nonAnnotatedClasses.add(targetClass);
if (logger.isTraceEnabled()) {
logger.trace("No @Scheduled annotations found on bean class: " + targetClass);
}
}
else {
// Non-empty set of methods
annotatedMethods.forEach((method, scheduledAnnotations) ->
scheduledAnnotations.forEach(scheduled -> processScheduled(scheduled, method, bean)));
if (logger.isTraceEnabled()) {
logger.trace(annotatedMethods.size() + " @Scheduled methods processed on bean '" + beanName +
"': " + annotatedMethods);
}
}
}
return bean;
}
}
这个方法,就是每一个bean
在初始化完成之后,都会进行调用
检查bean
方法上面,有无@Scheduled
或者@Schedules
并生成一个列表集合annotatedMethods
如果为空,就结束了
要是不为空,就进入到后续的逻辑,看这一行
annotatedMethods.forEach((method, scheduledAnnotations) -> scheduledAnnotations.forEach(scheduled -> processScheduled(scheduled, method, bean)));
所以,我们就都看看这个processScheduled(scheduled, method, bean)
方法里面做了什么
protected void processScheduled(Scheduled scheduled, Method method, Object bean) {
try {
Runnable runnable = createRunnable(bean, method);
boolean processedSchedule = false;
String errorMessage =
"Exactly one of the 'cron', 'fixedDelay(String)', or 'fixedRate(String)' attributes is required";
Set<ScheduledTask> tasks = new LinkedHashSet<>(4);
// Determine initial delay
long initialDelay = convertToMillis(scheduled.initialDelay(), scheduled.timeUnit());
String initialDelayString = scheduled.initialDelayString();
if (StringUtils.hasText(initialDelayString)) {
Assert.isTrue(initialDelay < 0, "Specify 'initialDelay' or 'initialDelayString', not both");
if (this.embeddedValueResolver != null) {
initialDelayString = this.embeddedValueResolver.resolveStringValue(initialDelayString);
}
if (StringUtils.hasLength(initialDelayString)) {
try {
initialDelay = convertToMillis(initialDelayString, scheduled.timeUnit());
}
catch (RuntimeException ex) {
throw new IllegalArgumentException(
"Invalid initialDelayString value \"" + initialDelayString + "\" - cannot parse into long");
}
}
}
// Check cron expression
String cron = scheduled.cron();
if (StringUtils.hasText(cron)) {
String zone = scheduled.zone();
if (this.embeddedValueResolver != null) {
cron = this.embeddedValueResolver.resolveStringValue(cron);
zone = this.embeddedValueResolver.resolveStringValue(zone);
}
if (StringUtils.hasLength(cron)) {
Assert.isTrue(initialDelay == -1, "'initialDelay' not supported for cron triggers");
processedSchedule = true;
if (!Scheduled.CRON_DISABLED.equals(cron)) {
TimeZone timeZone;
if (StringUtils.hasText(zone)) {
timeZone = StringUtils.parseTimeZoneString(zone);
}
else {
timeZone = TimeZone.getDefault();
}
tasks.add(this.registrar.scheduleCronTask(new CronTask(runnable, new CronTrigger(cron, timeZone))));
}
}
}
// At this point we don't need to differentiate between initial delay set or not anymore
if (initialDelay < 0) {
initialDelay = 0;
}
// Check fixed delay
long fixedDelay = convertToMillis(scheduled.fixedDelay(), scheduled.timeUnit());
if (fixedDelay >= 0) {
Assert.isTrue(!processedSchedule, errorMessage);
processedSchedule = true;
tasks.add(this.registrar.scheduleFixedDelayTask(new FixedDelayTask(runnable, fixedDelay, initialDelay)));
}
String fixedDelayString = scheduled.fixedDelayString();
if (StringUtils.hasText(fixedDelayString)) {
if (this.embeddedValueResolver != null) {
fixedDelayString = this.embeddedValueResolver.resolveStringValue(fixedDelayString);
}
if (StringUtils.hasLength(fixedDelayString)) {
Assert.isTrue(!processedSchedule, errorMessage);
processedSchedule = true;
try {
fixedDelay = convertToMillis(fixedDelayString, scheduled.timeUnit());
}
catch (RuntimeException ex) {
throw new IllegalArgumentException(
"Invalid fixedDelayString value \"" + fixedDelayString + "\" - cannot parse into long");
}
tasks.add(this.registrar.scheduleFixedDelayTask(new FixedDelayTask(runnable, fixedDelay, initialDelay)));
}
}
// Check fixed rate
long fixedRate = convertToMillis(scheduled.fixedRate(), scheduled.timeUnit());
if (fixedRate >= 0) {
Assert.isTrue(!processedSchedule, errorMessage);
processedSchedule = true;
tasks.add(this.registrar.scheduleFixedRateTask(new FixedRateTask(runnable, fixedRate, initialDelay)));
}
String fixedRateString = scheduled.fixedRateString();
if (StringUtils.hasText(fixedRateString)) {
if (this.embeddedValueResolver != null) {
fixedRateString = this.embeddedValueResolver.resolveStringValue(fixedRateString);
}
if (StringUtils.hasLength(fixedRateString)) {
Assert.isTrue(!processedSchedule, errorMessage);
processedSchedule = true;
try {
fixedRate = convertToMillis(fixedRateString, scheduled.timeUnit());
}
catch (RuntimeException ex) {
throw new IllegalArgumentException(
"Invalid fixedRateString value \"" + fixedRateString + "\" - cannot parse into long");
}
tasks.add(this.registrar.scheduleFixedRateTask(new FixedRateTask(runnable, fixedRate, initialDelay)));
}
}
// Check whether we had any attribute set
Assert.isTrue(processedSchedule, errorMessage);
// Finally register the scheduled tasks
synchronized (this.scheduledTasks) {
Set<ScheduledTask> regTasks = this.scheduledTasks.computeIfAbsent(bean, key -> new LinkedHashSet<>(4));
regTasks.addAll(tasks);
}
}
catch (IllegalArgumentException ex) {
throw new IllegalStateException(
"Encountered invalid @Scheduled method '" + method.getName() + "': " + ex.getMessage());
}
}
首先是转换了下initialDelay
然后检查了cron
表达式,fixedDelay
,fixedRate
无论使用上面哪种方式指定,都会创建一个ScheduledTask
加入到tasks
的列表中,如下
cron
表达式:tasks.add(this.registrar.scheduleCronTask(new CronTask(runnable, new CronTrigger(cron, timeZone))));
fixedDelay
:tasks.add(this.registrar.scheduleFixedDelayTask(new FixedDelayTask(runnable, fixedDelay, initialDelay)));
fixedRate
:tasks.add(this.registrar.scheduleFixedDelayTask(new FixedDelayTask(runnable, fixedDelay, initialDelay)));
当然啦,如果 tasks
为空,则代表上面的三种属性你都没有指定,那么就会报错了
Assert.isTrue(processedSchedule, errorMessage);
最后,将收集到的tasks
放入scheduledTasks
的Map
容器中
只讲了Spring
是如何解析注解,生成任务的
还差如何对这些任务进行执行,下篇再见
原创声明:本文系作者授权腾讯云开发者社区发表,未经许可,不得转载。
如有侵权,请联系 cloudcommunity@tencent.com 删除。
原创声明:本文系作者授权腾讯云开发者社区发表,未经许可,不得转载。
如有侵权,请联系 cloudcommunity@tencent.com 删除。