/*
 * 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.context.annotation;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import org.springframework.core.env.AbstractEnvironment;
import org.springframework.core.env.ConfigurableEnvironment;

/**
 * Indicates that a component is eligible for registration when one or more {@linkplain
 * #value specified profiles} are active.
 *
 * <p>A <em>profile</em> is a named logical grouping that may be activated
 * programmatically via {@link ConfigurableEnvironment#setActiveProfiles} or declaratively
 * through setting the {@link AbstractEnvironment#ACTIVE_PROFILES_PROPERTY_NAME
 * spring.profiles.active} property, usually through JVM system properties, as an
 * environment variable, or for web applications as a Servlet context parameter in
 * {@code web.xml}.
 *
 * <p>The {@code @Profile} annotation may be used in any of the following ways:
 * <ul>
 * <li>as a type-level annotation on any class directly or indirectly annotated with
 * {@code @Component}, including {@link Configuration @Configuration} classes
 * <li>as a meta-annotation, for the purpose of composing custom stereotype annotations
 * </ul>
 *
 * <p>If a {@code @Configuration} class is marked with {@code @Profile}, all of the
 * {@code @Bean} methods and {@link Import @Import} annotations associated with that class
 * will be bypassed unless one or more the specified profiles are active. This is very
 * similar to the behavior in Spring XML: if the {@code profile} attribute of the
 * {@code beans} element is supplied e.g., {@code <beans profile="p1,p2">}, the
 * {@code beans} element will not be parsed unless profiles 'p1' and/or 'p2' have been
 * activated.  Likewise, if a {@code @Component} or {@code @Configuration} class is marked
 * with {@code @Profile({"p1", "p2"})}, that class will not be registered/processed unless
 * profiles 'p1' and/or 'p2' have been activated.
 *
 * <p>If a given profile is prefixed with the NOT operator ({@code !}), the annotated
 * will be registered if the profile is <em>not</em> active. e.g., for
 * {@code @Profile({"p1", "!p2"})}, registration will occur if profile 'p1' is active or
 * if profile 'p2' is not active.
 *
 * <p>If the {@code @Profile} annotation is omitted, registration will occur, regardless
 * of which (if any) profiles are active.
 *
 * <p>When defining Spring beans via XML, the {@code "profile"} attribute of the
 * {@code <beans>} element may be used. See the documentation in
 * {@code spring-beans} XSD (version 3.1 or greater) for details.
 *
 * @author Chris Beams
 * @since 3.1
 * @see ConfigurableEnvironment#setActiveProfiles
 * @see ConfigurableEnvironment#setDefaultProfiles
 * @see AbstractEnvironment#ACTIVE_PROFILES_PROPERTY_NAME
 * @see AbstractEnvironment#DEFAULT_PROFILES_PROPERTY_NAME
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface Profile {

	/**
	 * The set of profiles for which this component should be registered.
	 */
	String[] value();

}
