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/*
* Copyright 2002-2012 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
*
* http://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;
/**
* Annotation that marks a method as a candidate for asynchronous execution.
* Can also be used at the type level, in which case all of the type's methods are
* considered as asynchronous.
*
* 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, the {@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 the return value through: e.g.
* Spring's {@link AsyncResult} or EJB 3.1's {@link javax.ejb.AsyncResult}.
*
* @author Juergen Hoeller
* @author Chris Beams
* @since 3.0
* @see AnnotationAsyncExecutionInterceptor
* @see AsyncAnnotationAdvisor
*/
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
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 this
* method, 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 on a class level {@code @Async} annotation, indicates that the
* given executor should be used for all methods within the class. Method level use
* of {@link Async#value} always overrides any value set at the class level.
* @since 3.1.2
*/
String value() default "";
}