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/*
 * Copyright 2002-2021 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.context.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;

/**
 * Enables support for handling components marked with AspectJ's {@code @Aspect} annotation,
 * similar to functionality found in Spring's {@code } XML element.
 * To be used on @{@link Configuration} classes as follows:
 *
 * 
 * @Configuration
 * @EnableAspectJAutoProxy
 * public class AppConfig {
 *
 *     @Bean
 *     public FooService fooService() {
 *         return new FooService();
 *     }
 *
 *     @Bean
 *     public MyAspect myAspect() {
 *         return new MyAspect();
 *     }
 * }
* * Where {@code FooService} is a typical POJO component and {@code MyAspect} is an * {@code @Aspect}-style aspect: * *
 * public class FooService {
 *
 *     // various methods
 * }
* *
 * @Aspect
 * public class MyAspect {
 *
 *     @Before("execution(* FooService+.*(..))")
 *     public void advice() {
 *         // advise FooService methods as appropriate
 *     }
 * }
* * In the scenario above, {@code @EnableAspectJAutoProxy} ensures that {@code MyAspect} * will be properly processed and that {@code FooService} will be proxied mixing in the * advice that it contributes. * *

Users can control the type of proxy that gets created for {@code FooService} using * the {@link #proxyTargetClass()} attribute. The following enables CGLIB-style 'subclass' * proxies as opposed to the default interface-based JDK proxy approach. * *

 * @Configuration
 * @EnableAspectJAutoProxy(proxyTargetClass=true)
 * public class AppConfig {
 *     // ...
 * }
* *

Note that {@code @Aspect} beans may be component-scanned like any other. * Simply mark the aspect with both {@code @Aspect} and {@code @Component}: * *

 * package com.foo;
 *
 * @Component
 * public class FooService { ... }
 *
 * @Aspect
 * @Component
 * public class MyAspect { ... }
* * Then use the @{@link ComponentScan} annotation to pick both up: * *
 * @Configuration
 * @ComponentScan("com.foo")
 * @EnableAspectJAutoProxy
 * public class AppConfig {
 *
 *     // no explicit @Bean definitions required
 * }
* * Note: {@code @EnableAspectJAutoProxy} applies to its local application context only, * allowing for selective proxying of beans at different levels. Please redeclare * {@code @EnableAspectJAutoProxy} in each individual context, e.g. the common root web * application context and any separate {@code DispatcherServlet} application contexts, * if you need to apply its behavior at multiple levels. * *

This feature requires the presence of {@code aspectjweaver} on the classpath. * While that dependency is optional for {@code spring-aop} in general, it is required * for {@code @EnableAspectJAutoProxy} and its underlying facilities. * * @author Chris Beams * @author Juergen Hoeller * @since 3.1 * @see org.aspectj.lang.annotation.Aspect */ @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) @Documented @Import(AspectJAutoProxyRegistrar.class) public @interface EnableAspectJAutoProxy { /** * Indicate whether subclass-based (CGLIB) proxies are to be created as opposed * to standard Java interface-based proxies. The default is {@code false}. */ boolean proxyTargetClass() default false; /** * Indicate that the proxy should be exposed by the AOP framework as a {@code ThreadLocal} * for retrieval via the {@link org.springframework.aop.framework.AopContext} class. * Off by default, i.e. no guarantees that {@code AopContext} access will work. * @since 4.3.1 */ boolean exposeProxy() default false; }





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