spring-: spring-bean-lifecycle-execution-order

This article comprehensively analyzes the life cycle of Spring Bean, which covers all related life cycle interfaces and methods covering the BeanFactory interface to fully present the operating process of Bean.

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I. Spring Bean Life Cycle logic execution order (from instantiation to destruction)

(instantiated to destruction)

Loading bean definition (metadata processing)

1. Spring from the

   configuration file (@Configuration), XML file or component scan (@Component)
   read bean definition.
   • This is metadata processing steps , no instance has been created.
   • Related method:
   • BeanDefinitionRegistry#registerBeanDefinition()
bean instantiated (created by object)

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2. Create the actual bean object through the following ways:

   The constructive function is instantiated

   Factory method
   • • Related method:
   • Set the bean name InstantiationAwareBeanPostProcessor#postProcessBeforeInstantiation() (
   )

If bean implement

---

, Spring will call

Method to
3. inform Bean's own name

   . This happened before before the injection BeanNameAware#setBeanName(String name).

   Use case:
   • If bean needs to know its name BeanNameAware in the context of the application. setBeanName()
   • Set the bean class loader ()
   If bean needs to access its class loader
   , Spring will call this method.

Usage:

public class MyBean implements BeanNameAware {
    @Override
    public void setBeanName(String name) {
        System.out.println("Bean Name Set: " + name);
    }
}

If bean

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dynamically load the class

at runtime.

4. BeanClassLoaderAware#setBeanClassLoader(ClassLoader classLoader)

   • Set Beanfactory (
   )
   • Spring Injects Beanfactory into Bean.
   Use case:
Allow bean

Get other bean

public class MyBean implements BeanClassLoaderAware {
    @Override
    public void setBeanClassLoader(ClassLoader classLoader) {
        System.out.println("ClassLoader Set!");
    }
}

by programming.

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5. BeanFactoryAware#setBeanFactory(BeanFactory factory)

   Set the environment
   • ()
   • If bean needs to access environment variables and attributes , this method will be called. Use case:
   Used to dynamically access the value in
   .

public class MyBean implements BeanFactoryAware {
    @Override
    public void setBeanFactory(BeanFactory beanFactory) {
        System.out.println("BeanFactory Set!");
    }
}

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6. Set the embedded value parser EnvironmentAware#setEnvironment(Environment environment) (

   )
   • Allowed bean Analyzing the placement of placement ($ {Property})
   .
   • Usage: When bean needs manually parsing the placeholder is useful.

public class MyBean implements BeanNameAware {
    @Override
    public void setBeanName(String name) {
        System.out.println("Bean Name Set: " + name);
    }
}

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8. Set the resource loader () ResourceLoaderAware#setResourceLoader(ResourceLoader loader)

   Only applies to
   • ApplicationContext for dynamic loading resources.
   Use case:
   • Loading files, class path resources or external resources.

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Set the application event publisher
9. (

   ) ApplicationEventPublisherAware#setApplicationEventPublisher(ApplicationEventPublisher publisher) If bean needs

   to publish an event
   , this method will be called.
   • Use case: Used for broadcasting events, such as
   .
   • ContextRefreshedEvent

Set the message source

---

(

)

10. If bean needs Internationalization (I18N) to support MessageSourceAware#setMessageSource(MessageSource source), Spring will inject MessageSource.
Set ApplicationContext

(

---

)

11. If bean needs to access the entire Spring ApplicationContext , this method will be called. ApplicationContextAware#setApplicationContext(ApplicationContext ctx)

    Example:
    Allow dynamic access to
    • other beans, environmental settings, etc. .
    Set the servertContext
    (
)

---

Only applicable to
12. Web applications

    , used to access the Web context information . ServletContextAware#setServletContext(ServletContext ctx)

    • The post -processing before the initialization
    (
    )

---

Allowed

before bean
13. before the

    modified bean. BeanPostProcessor#postProcessBeforeInitialization()

    • Customized initialization

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14. Custom Method

    Custom

    • InitializingBean afterPropertiesSet()
    • @PostConstruct
    After the initialized post -treatment
    • (@Bean) init-method
    Allow bean to initialize
later

modify bean.

public class MyBean implements BeanClassLoaderAware {
    @Override
    public void setBeanClassLoader(ClassLoader classLoader) {
        System.out.println("ClassLoader Set!");
    }
}

---

Example:

Used to create proxy, log records or face -oriented programming (AOP)
15. .

    BeanPostProcessor#postProcessAfterInitialization()

    • bean available
    • Bean has completely initialized and can be used for applications.

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2. Destruction stage (bean close the life cycle)

When the application is closed, Spring will be elegant

destroyed bean

.

The treatment before destroyed
1. (

   ) DestructionAwareBeanPostProcessor#postProcessBeforeDestruction() Allows to clean up before the destroy

   .
   The
Method

2. DisposableBean If bean is implemented, destroy() will be called.

   • DisposableBean destroy()
   Custom
Method (preferred method)

public class MyBean implements BeanNameAware {
    @Override
    public void setBeanName(String name) {
        System.out.println("Bean Name Set: " + name);
    }
}

3. is more modern than , and

   call before bean destroyed . @PreDestroy

   • DisposableBean Custom
   (If defined in
   )

public class MyBean implements BeanClassLoaderAware {
    @Override
    public void setBeanClassLoader(ClassLoader classLoader) {
        System.out.println("ClassLoader Set!");
    }
}

Define the alternative method of cleaning the logic.

4. destroy-method @Bean Three, the complete process summary (final order)

   • ? Bean initialization stage

Load bean definition

---

instantiated bean ()

(

) (

)

1. (
)
2. new Bean() (
)
3. setBeanName() (BeanNameAware)
4. (setBeanClassLoader()) BeanClassLoaderAware
(
5. ) setBeanFactory() BeanFactoryAware (
)
6. setEnvironment() (EnvironmentAware)
7. (setEmbeddedValueResolver()) EmbeddedValueResolverAware
(
8. ) setResourceLoader() ResourceLoaderAware /
9. setApplicationEventPublisher() (ApplicationEventPublisherAware)
10. bean available setMessageSource() MessageSourceAware
11. setApplicationContext() ? Bean's destruction stage ApplicationContextAware
12. setServletContext() (ServletContextAware)
13. (postProcessBeforeInitialization()) BeanPostProcessor
14. @PostConstruct afterPropertiesSet()
15. postProcessAfterInitialization() More information about interface and methods, please visit: BeanPostProcessor https://www.php.cn/link/6759d0996526ddc8e27aa550F0B806B1
16. I wish you a happy coding! ?

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