https://github.com/spring-projects/spring-framework: Spring Context (Spring IO)
  • Juergen Hoeller 
/*
 * Copyright 2002-2018 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.Annotation;
import java.util.concurrent.Executor;
import java.util.function.Supplier;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.aop.framework.autoproxy.AbstractBeanFactoryAwareAdvisingPostProcessor;
import org.springframework.aop.interceptor.AsyncUncaughtExceptionHandler;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.core.task.TaskExecutor;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.function.SingletonSupplier;


Bean post-processor that automatically applies asynchronous invocation behavior to any bean that carries the Async annotation at class or method-level by adding a corresponding AsyncAnnotationAdvisor to the exposed proxy (either an existing AOP proxy or a newly generated proxy that implements all of the target's interfaces). 
The TaskExecutor responsible for the asynchronous execution may be provided as well as the annotation type that indicates a method should be invoked asynchronously. If no annotation type is specified, this post- processor will detect both Spring's @Async annotation as well as the EJB 3.1 javax.ejb.Asynchronous annotation. 
For methods having a void return type, any exception thrown during the asynchronous method invocation cannot be accessed by the caller. An AsyncUncaughtExceptionHandler can be specified to handle these cases. 
Note: The underlying async advisor applies before existing advisors by default,
in order to switch to async execution as early as possible in the invocation chain.

Author:Mark Fisher, Juergen Hoeller, Stephane Nicoll
See Also:
Since:3.0
/**
 * Bean post-processor that automatically applies asynchronous invocation
 * behavior to any bean that carries the {@link Async} annotation at class or
 * method-level by adding a corresponding {@link AsyncAnnotationAdvisor} to the
 * exposed proxy (either an existing AOP proxy or a newly generated proxy that
 * implements all of the target's interfaces).
 *
 * <p>The {@link TaskExecutor} responsible for the asynchronous execution may
 * be provided as well as the annotation type that indicates a method should be
 * invoked asynchronously. If no annotation type is specified, this post-
 * processor will detect both Spring's {@link Async @Async} annotation as well
 * as the EJB 3.1 {@code javax.ejb.Asynchronous} annotation.
 *
 * <p>For methods having a {@code void} return type, any exception thrown
 * during the asynchronous method invocation cannot be accessed by the
 * caller. An {@link AsyncUncaughtExceptionHandler} can be specified to handle
 * these cases.
 *
 * <p>Note: The underlying async advisor applies before existing advisors by default,
 * in order to switch to async execution as early as possible in the invocation chain.
 *
 * @author Mark Fisher
 * @author Juergen Hoeller
 * @author Stephane Nicoll
 * @since 3.0
 * @see Async
 * @see AsyncAnnotationAdvisor
 * @see #setBeforeExistingAdvisors
 * @see ScheduledAnnotationBeanPostProcessor
 */
@SuppressWarnings("serial")
public class AsyncAnnotationBeanPostProcessor extends AbstractBeanFactoryAwareAdvisingPostProcessor {

	
The default name of the TaskExecutor bean to pick up: "taskExecutor". 
Note that the initial lookup happens by type; this is just the fallback
in case of multiple executor beans found in the context.

See Also:
Since:4.2
/**
	 * The default name of the {@link TaskExecutor} bean to pick up: "taskExecutor".
	 * <p>Note that the initial lookup happens by type; this is just the fallback
	 * in case of multiple executor beans found in the context.
	 * @since 4.2
	 * @see AnnotationAsyncExecutionInterceptor#DEFAULT_TASK_EXECUTOR_BEAN_NAME
	 */
	public static final String DEFAULT_TASK_EXECUTOR_BEAN_NAME =
			AnnotationAsyncExecutionInterceptor.DEFAULT_TASK_EXECUTOR_BEAN_NAME;


	protected final Log logger = LogFactory.getLog(getClass());

	@Nullable
	private Supplier<Executor> executor;

	@Nullable
	private Supplier<AsyncUncaughtExceptionHandler> exceptionHandler;

	@Nullable
	private Class<? extends Annotation> asyncAnnotationType;



	public AsyncAnnotationBeanPostProcessor() {
		setBeforeExistingAdvisors(true);
	}


	
Configure this post-processor with the given executor and exception handler suppliers,
applying the corresponding default if a supplier is not resolvable.

Since:5.1
/**
	 * Configure this post-processor with the given executor and exception handler suppliers,
	 * applying the corresponding default if a supplier is not resolvable.
	 * @since 5.1
	 */
	public void configure(
			@Nullable Supplier<Executor> executor, @Nullable Supplier<AsyncUncaughtExceptionHandler> exceptionHandler) {

		this.executor = executor;
		this.exceptionHandler = exceptionHandler;
	}

	
Set the Executor to use when invoking methods asynchronously. 
If not specified, default executor resolution will apply: searching for a unique TaskExecutor bean in the context, or for an Executor bean named "taskExecutor" otherwise. If neither of the two is resolvable, a local default executor will be created within the interceptor. 
See Also:
/**
	 * Set the {@link Executor} to use when invoking methods asynchronously.
	 * <p>If not specified, default executor resolution will apply: searching for a
	 * unique {@link TaskExecutor} bean in the context, or for an {@link Executor}
	 * bean named "taskExecutor" otherwise. If neither of the two is resolvable,
	 * a local default executor will be created within the interceptor.
	 * @see AnnotationAsyncExecutionInterceptor#getDefaultExecutor(BeanFactory)
	 * @see #DEFAULT_TASK_EXECUTOR_BEAN_NAME
	 */
	public void setExecutor(Executor executor) {
		this.executor = SingletonSupplier.of(executor);
	}

	
Set the AsyncUncaughtExceptionHandler to use to handle uncaught exceptions thrown by asynchronous method executions. 
Since:4.1
/**
	 * Set the {@link AsyncUncaughtExceptionHandler} to use to handle uncaught
	 * exceptions thrown by asynchronous method executions.
	 * @since 4.1
	 */
	public void setExceptionHandler(AsyncUncaughtExceptionHandler exceptionHandler) {
		this.exceptionHandler = SingletonSupplier.of(exceptionHandler);
	}

	
Set the 'async' annotation type to be detected at either class or method level. By default, both the Async annotation and the EJB 3.1 javax.ejb.Asynchronous annotation will be detected. 
This setter property exists so that developers can provide their own
(non-Spring-specific) annotation type to indicate that a method (or all
methods of a given class) should be invoked asynchronously.

Params:
  • asyncAnnotationType – the desired annotation type
/**
	 * Set the 'async' annotation type to be detected at either class or method
	 * level. By default, both the {@link Async} annotation and the EJB 3.1
	 * {@code javax.ejb.Asynchronous} annotation will be detected.
	 * <p>This setter property exists so that developers can provide their own
	 * (non-Spring-specific) annotation type to indicate that a method (or all
	 * methods of a given class) should be invoked asynchronously.
	 * @param asyncAnnotationType the desired annotation type
	 */
	public void setAsyncAnnotationType(Class<? extends Annotation> asyncAnnotationType) {
		Assert.notNull(asyncAnnotationType, "'asyncAnnotationType' must not be null");
		this.asyncAnnotationType = asyncAnnotationType;
	}


	@Override
	public void setBeanFactory(BeanFactory beanFactory) {
		super.setBeanFactory(beanFactory);

		AsyncAnnotationAdvisor advisor = new AsyncAnnotationAdvisor(this.executor, this.exceptionHandler);
		if (this.asyncAnnotationType != null) {
			advisor.setAsyncAnnotationType(this.asyncAnnotationType);
		}
		advisor.setBeanFactory(beanFactory);
		this.advisor = advisor;
	}

}