org.springframework.context.annotation.Lazy Maven / Gradle / Ivy
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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;
/**
* Indicates whether a bean is to be lazily initialized.
*
* May be used on any class directly or indirectly annotated with {@link
* org.springframework.stereotype.Component @Component} or on methods annotated with
* {@link Bean @Bean}.
*
*
If this annotation is not present on a {@code @Component} or {@code @Bean} definition,
* eager initialization will occur. If present and set to {@code true}, the {@code @Bean} or
* {@code @Component} will not be initialized until referenced by another bean or explicitly
* retrieved from the enclosing {@link org.springframework.beans.factory.BeanFactory
* BeanFactory}. If present and set to {@code false}, the bean will be instantiated on
* startup by bean factories that perform eager initialization of singletons.
*
*
If Lazy is present on a {@link Configuration @Configuration} class, this
* indicates that all {@code @Bean} methods within that {@code @Configuration}
* should be lazily initialized. If {@code @Lazy} is present and false on a {@code @Bean}
* method within a {@code @Lazy}-annotated {@code @Configuration} class, this indicates
* overriding the 'default lazy' behavior and that the bean should be eagerly initialized.
*
*
In addition to its role for component initialization, this annotation may also be placed
* on injection points marked with {@link org.springframework.beans.factory.annotation.Autowired}
* or {@link jakarta.inject.Inject}: In that context, it leads to the creation of a
* lazy-resolution proxy for all affected dependencies, as an alternative to using
* {@link org.springframework.beans.factory.ObjectFactory} or {@link jakarta.inject.Provider}.
* Please note that such a lazy-resolution proxy will always be injected; if the target
* dependency does not exist, you will only be able to find out through an exception on
* invocation. As a consequence, such an injection point results in unintuitive behavior
* for optional dependencies. For a programmatic equivalent, allowing for lazy references
* with more sophistication, consider {@link org.springframework.beans.factory.ObjectProvider}.
*
* @author Chris Beams
* @author Juergen Hoeller
* @since 3.0
* @see Primary
* @see Bean
* @see Configuration
* @see org.springframework.stereotype.Component
*/
@Target({ElementType.TYPE, ElementType.METHOD, ElementType.CONSTRUCTOR, ElementType.PARAMETER, ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Lazy {
/**
* Whether lazy initialization should occur.
*/
boolean value() default true;
}