Package org.springframework.scheduling.annotation

# Annotation Interface EnableScheduling

@Target(TYPE) @Retention(RUNTIME) @Import(SchedulingConfiguration.class) @Documented public @interface EnableScheduling
Enables Spring's scheduled task execution capability, similar to functionality found in Spring's `<task:*>` XML namespace. To be used on `@Configuration` classes as follows:

     @Configuration
     @EnableScheduling
     public class AppConfig {

         // various @Bean definitions
     }

This enables detection of `@Scheduled` annotations on any Spring-managed bean in the container. For example, given a class `MyTask`:

     package com.myco.tasks;

     public class MyTask {

         @Scheduled(fixedRate=1000)
         public void work() {
             // task execution logic
         }
     }

the following configuration would ensure that `MyTask.work()` is called once every 1000 ms:

     @Configuration
     @EnableScheduling
     public class AppConfig {

         @Bean
         public MyTask task() {
             return new MyTask();
         }
     }

Alternatively, if `MyTask` were annotated with `@Component`, the following configuration would ensure that its `@Scheduled` method is invoked at the desired interval:

     @Configuration
     @EnableScheduling
     @ComponentScan(basePackages="com.myco.tasks")
     public class AppConfig {
     }

Methods annotated with `@Scheduled` may even be declared directly within `@Configuration` classes:

     @Configuration
     @EnableScheduling
     public class AppConfig {

         @Scheduled(fixedRate=1000)
         public void work() {
             // task execution logic
         }
     }

By default, Spring will search for an associated scheduler definition: either a unique `TaskScheduler` bean in the context, or a `TaskScheduler` bean named "taskScheduler" otherwise; the same lookup will also be performed for a `ScheduledExecutorService` bean. If neither of the two is resolvable, a local single-threaded default scheduler will be created and used within the registrar.

When more control is desired, a `@Configuration` class may implement `SchedulingConfigurer`. This allows access to the underlying `ScheduledTaskRegistrar` instance. For example, the following example demonstrates how to customize the `Executor` used to execute scheduled tasks:

     @Configuration
     @EnableScheduling
     public class AppConfig implements SchedulingConfigurer {

         @Override
         public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
             taskRegistrar.setScheduler(taskExecutor());
         }

         @Bean(destroyMethod="shutdown")
         public Executor taskExecutor() {
             return Executors.newScheduledThreadPool(100);
         }
     }

Note in the example above the use of `@Bean(destroyMethod="shutdown")`. This ensures that the task executor is properly shut down when the Spring application context itself is closed.

Implementing `SchedulingConfigurer` also allows for fine-grained control over task registration via the `ScheduledTaskRegistrar`. For example, the following configures the execution of a particular bean method per a custom `Trigger` implementation:

     @Configuration
     @EnableScheduling
     public class AppConfig implements SchedulingConfigurer {

         @Override
         public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
             taskRegistrar.setScheduler(taskScheduler());
             taskRegistrar.addTriggerTask(
                 () -> myTask().work(),
                 new CustomTrigger()
             );
         }

         @Bean(destroyMethod="shutdown")
         public Executor taskScheduler() {
             return Executors.newScheduledThreadPool(42);
         }

         @Bean
         public MyTask myTask() {
             return new MyTask();
         }
     }

For reference, the example above can be compared to the following Spring XML configuration:

     <beans>

         <task:annotation-driven scheduler="taskScheduler"/>

         <task:scheduler id="taskScheduler" pool-size="42"/>

         <task:scheduled-tasks scheduler="taskScheduler">
             <task:scheduled ref="myTask" method="work" fixed-rate="1000"/>
         </task:scheduled-tasks>

         <bean id="myTask" class="com.foo.MyTask"/>

     </beans>

The examples are equivalent save that in XML a fixed-rate period is used instead of a custom `Trigger` implementation; this is because the `task:` namespace `scheduled` cannot easily expose such support. This is but one demonstration how the code-based approach allows for maximum configurability through direct access to the actual component.

Note: `@EnableScheduling` applies to its local application context only, allowing for selective scheduling of beans at different levels. Please redeclare `@EnableScheduling` in each individual context, for example, the common root web application context and any separate `DispatcherServlet` application contexts, if you need to apply its behavior at multiple levels.

Since:
  3.1
Author:
  Chris Beams, Juergen Hoeller
See Also:
  - `Scheduled`
  - `SchedulingConfiguration`
  - `SchedulingConfigurer`
  - `ScheduledTaskRegistrar`
  - `Trigger`
  - `ScheduledAnnotationBeanPostProcessor`