org.springframework.scheduling.annotation.Async Maven / Gradle / Ivy
/*
* Copyright 2002-2022 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
*
* https://www.apache.org/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.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.springframework.aot.hint.annotation.Reflective;
/**
* Annotation that marks a method as a candidate for asynchronous execution.
*
* Can also be used at the type level, in which case all the type's methods are
* considered as asynchronous. Note, however, that {@code @Async} is not supported
* on methods declared within a
* {@link org.springframework.context.annotation.Configuration @Configuration} class.
*
*
In terms of target method signatures, any parameter types are supported.
* However, the return type is constrained to either {@code void} or
* {@link java.util.concurrent.Future}. In the latter case, you may declare the
* more specific {@link org.springframework.util.concurrent.ListenableFuture} or
* {@link java.util.concurrent.CompletableFuture} types which allow for richer
* interaction with the asynchronous task and for immediate composition with
* further processing steps.
*
*
A {@code Future} handle returned from the proxy will be an actual asynchronous
* {@code Future} that can be used to track the result of the asynchronous method
* execution. However, since the target method needs to implement the same signature,
* it will have to return a temporary {@code Future} handle that just passes a value
* through: for example, Spring's {@link AsyncResult}, EJB 3.1's {@link jakarta.ejb.AsyncResult},
* or {@link java.util.concurrent.CompletableFuture#completedFuture(Object)}.
*
* @author Juergen Hoeller
* @author Chris Beams
* @since 3.0
* @see AnnotationAsyncExecutionInterceptor
* @see AsyncAnnotationAdvisor
*/
@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Reflective
public @interface Async {
/**
* A qualifier value for the specified asynchronous operation(s).
*
May be used to determine the target executor to be used when executing
* the asynchronous operation(s), matching the qualifier value (or the bean
* name) of a specific {@link java.util.concurrent.Executor Executor} or
* {@link org.springframework.core.task.TaskExecutor TaskExecutor}
* bean definition.
*
When specified in a class-level {@code @Async} annotation, indicates that the
* given executor should be used for all methods within the class. Method-level use
* of {@code Async#value} always overrides any qualifier value configured at
* the class level.
*
The qualifier value will be resolved dynamically if supplied as a SpEL
* expression (for example, {@code "#{environment['myExecutor']}"}) or a
* property placeholder (for example, {@code "${my.app.myExecutor}"}).
* @since 3.1.2
*/
String value() default "";
}