Overview | Package | Class | Tree | Deprecated | Index | Help
PREV CLASS NEXT CLASS | FRAMES NO FRAMES
SUMMARY: REQUIRED | OPTIONAL | DETAIL: ELEMENT

## org.springframework.scheduling.annotation
Annotation Type EnableScheduling

    @Target(value=TYPE)
    @Retention(value=RUNTIME)
    @Import(value=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
     @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
         }
     }

In all of the above scenarios, a default single-threaded task executor is used. 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(
                 new Runnable() {
                     public void run() {
                         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-config scheduler="taskScheduler"/>
         <task:scheduler id="taskScheduler" pool-size="42"/>
         <task:scheduled ref="myTask" method="work" fixed-rate="1000"/>
         <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 actual componentry.

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

Overview | Package | Class | Tree | Deprecated | Index | Help
PREV CLASS NEXT CLASS | FRAMES NO FRAMES
SUMMARY: REQUIRED | OPTIONAL | DETAIL: ELEMENT