Modernize the lazy-initialized beans refdoc section
Closes gh-32767
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@ -10,33 +10,25 @@ pre-instantiation of a singleton bean by marking the bean definition as being
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lazy-initialized. A lazy-initialized bean tells the IoC container to create a bean
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instance when it is first requested, rather than at startup.
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In XML, this behavior is controlled by the `lazy-init` attribute on the `<bean/>`
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element, as the following example shows:
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This behavior is controlled by the `@Lazy` annotation or in XML the `lazy-init` attribute on the `<bean/>` element, as
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the following example shows:
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[source,xml,indent=0,subs="verbatim,quotes"]
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----
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<bean id="lazy" class="com.something.ExpensiveToCreateBean" lazy-init="true"/>
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<bean name="not.lazy" class="com.something.AnotherBean"/>
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----
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include-code::./ApplicationConfiguration[tag=snippet,indent=0]
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When the preceding configuration is consumed by an `ApplicationContext`, the `lazy` bean
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is not eagerly pre-instantiated when the `ApplicationContext` starts,
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whereas the `not.lazy` bean is eagerly pre-instantiated.
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whereas the `notLazy` one is eagerly pre-instantiated.
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However, when a lazy-initialized bean is a dependency of a singleton bean that is
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not lazy-initialized, the `ApplicationContext` creates the lazy-initialized bean at
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startup, because it must satisfy the singleton's dependencies. The lazy-initialized bean
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is injected into a singleton bean elsewhere that is not lazy-initialized.
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You can also control lazy-initialization at the container level by using the
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`default-lazy-init` attribute on the `<beans/>` element, as the following example shows:
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You can also control lazy-initialization for a set of beans by using the `@Lazy` annotation on your `@Configuration`
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annotated class or in XML using the `default-lazy-init` attribute on the `<beans/>` element, as the following example
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shows:
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[source,xml,indent=0,subs="verbatim,quotes"]
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----
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<beans default-lazy-init="true">
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<!-- no beans will be pre-instantiated... -->
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</beans>
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----
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include-code::./LazyConfiguration[tag=snippet,indent=0]
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@ -0,0 +1,20 @@
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/*
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* Copyright 2002-2024 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.docs.core.beans.dependencies.beansfactorylazyinit;
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public class AnotherBean {
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}
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@ -0,0 +1,38 @@
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/*
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* Copyright 2002-2024 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.docs.core.beans.dependencies.beansfactorylazyinit;
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import org.springframework.context.annotation.Bean;
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import org.springframework.context.annotation.Configuration;
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import org.springframework.context.annotation.Lazy;
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@Configuration
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public class ApplicationConfiguration {
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// tag::snippet[]
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@Bean
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@Lazy
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ExpensiveToCreateBean lazy() {
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return new ExpensiveToCreateBean();
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}
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@Bean
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AnotherBean notLazy() {
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return new AnotherBean();
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}
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// end::snippet[]
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}
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@ -0,0 +1,20 @@
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/*
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* Copyright 2002-2024 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.docs.core.beans.dependencies.beansfactorylazyinit;
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public class ExpensiveToCreateBean {
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}
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@ -0,0 +1,28 @@
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/*
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* Copyright 2002-2024 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.docs.core.beans.dependencies.beansfactorylazyinit;
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import org.springframework.context.annotation.Configuration;
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import org.springframework.context.annotation.Lazy;
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// tag::snippet[]
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@Configuration
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@Lazy
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public class LazyConfiguration {
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// No bean will be pre-instantiated...
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}
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// end::snippet[]
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@ -0,0 +1,38 @@
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/*
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* Copyright 2002-2024 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.docs.core.beans.dependencies.beansfactorylazyinit
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import org.springframework.context.annotation.Bean
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import org.springframework.context.annotation.Configuration
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import org.springframework.context.annotation.Lazy
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@Configuration
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class ApplicationConfiguration {
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// tag::snippet[]
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@Bean
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@Lazy
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fun lazy(): ExpensiveToCreateBean {
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return ExpensiveToCreateBean()
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}
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@Bean
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fun notLazy(): AnotherBean {
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return AnotherBean()
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}
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// end::snippet[]
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}
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@ -0,0 +1,27 @@
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/*
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* Copyright 2002-2024 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.docs.core.beans.dependencies.beansfactorylazyinit
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import org.springframework.context.annotation.Configuration
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import org.springframework.context.annotation.Lazy
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// tag::snippet[]
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@Configuration
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@Lazy
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class LazyConfiguration {
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// No bean will be pre-instantiated...
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}
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// end::snippet[]
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@ -0,0 +1,12 @@
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<beans xmlns="http://www.springframework.org/schema/beans"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://www.springframework.org/schema/beans
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https://www.springframework.org/schema/beans/spring-beans.xsd">
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<!-- tag::snippet[] -->
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<bean id="lazy" class="com.something.ExpensiveToCreateBean" lazy-init="true"/>
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<bean name="notLazy" class="com.something.AnotherBean"/>
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<!-- end::snippet[] -->
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</beans>
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@ -0,0 +1,6 @@
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<!-- tag::snippet[] -->
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<beans default-lazy-init="true">
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<!-- No bean will be pre-instantiated... -->
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</beans>
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<!-- end::snippet[] -->
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