/spring-annotation

spring annotation

Primary LanguageJava

Spring 注解

根据 link 的学习记录

  • 基于 spring 5.3.15

1. 思维导图

思维导图

img.png

2. Scope

Scope

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3. life cycle

doCreateBean

  • 真正创建 bena 的地方: org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean
// https://juejin.cn/post/6844904065457979405
// AbstractAutowireCapableBeanFactory.java
protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final @Nullable Object[] args)
    throws BeanCreationException {

    // 1. 实例化
    BeanWrapper instanceWrapper = null;
    if (instanceWrapper == null) {
        instanceWrapper = createBeanInstance(beanName, mbd, args);
    }
    
    Object exposedObject = bean;
    try {
        // 2. 属性赋值
        populateBean(beanName, mbd, instanceWrapper);
        // 3. 初始化
        exposedObject = initializeBean(beanName, exposedObject, mbd);
    }

    // 4. 销毁-注册回调接口
    try {
        registerDisposableBeanIfNecessary(beanName, bean, mbd);
    }

    return exposedObject;
}

initializeBean

// AbstractAutowireCapableBeanFactory.java
protected Object initializeBean(final String beanName, final Object bean, @Nullable RootBeanDefinition mbd) {
    // 3. 检查 Aware 相关接口并设置相关依赖
    if (System.getSecurityManager() != null) {
        AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
            invokeAwareMethods(beanName, bean);
            return null;
        }, getAccessControlContext());
    }
    else {
        invokeAwareMethods(beanName, bean);
    }

    // 4. BeanPostProcessor 前置处理
    Object wrappedBean = bean;
    if (mbd == null || !mbd.isSynthetic()) {
        wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
    }

    // 5. 若实现 InitializingBean 接口，调用 afterPropertiesSet() 方法
    // 6. 若配置自定义的 init-method方法，则执行
    try {
        invokeInitMethods(beanName, wrappedBean, mbd);
    }
    catch (Throwable ex) {
        throw new BeanCreationException(
            (mbd != null ? mbd.getResourceDescription() : null),
            beanName, "Invocation of init method failed", ex);
    }
    // 7. BeanPostProceesor 后置处理
    if (mbd == null || !mbd.isSynthetic()) {
        wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
    }

    return wrappedBean;
}

invokInitMethods

// DisposableBeanAdapter.java
public void destroy() {
    // 9. 若实现 DisposableBean 接口，则执行 destory()方法
    if (this.invokeDisposableBean) {
        try {
            if (System.getSecurityManager() != null) {
                AccessController.doPrivileged((PrivilegedExceptionAction<Object>) () -> {
                    ((DisposableBean) this.bean).destroy();
                    return null;
                }, this.acc);
            }
            else {
                ((DisposableBean) this.bean).destroy();
            }
        }
    }
    
	// 10. 若配置自定义的 detory-method 方法，则执行
    if (this.destroyMethod != null) {
        invokeCustomDestroyMethod(this.destroyMethod);
    }
    else if (this.destroyMethodName != null) {
        Method methodToInvoke = determineDestroyMethod(this.destroyMethodName);
        if (methodToInvoke != null) {
            invokeCustomDestroyMethod(ClassUtils.getInterfaceMethodIfPossible(methodToInvoke));
        }
    }
}

bean 的生命周期 来自

img.png

总结: spring 中的 *Aware 接口及对应的功能

aware 接口有两个执行时机

protected Object initializeBean(String beanName, Object bean, @Nullable RootBeanDefinition mbd) {
    
    // 第一次
    invokeAwareMethods(beanName, bean);
    
    // 第二次
    wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);

    // ...
    return wrappedBean;
}
  • 第一次执行
    • BeanNameAware：注入当前 bean 对应 beanName；
    • BeanClassLoaderAware：注入加载当前 bean 的 ClassLoader；
    • BeanFactoryAware：注入 当前BeanFactory容器 的引用。
// AbstractAutowireCapableBeanFactory.java
private void invokeAwareMethods(final String beanName, final Object bean) {
    if (bean instanceof Aware) {
        if (bean instanceof BeanNameAware) {
            ((BeanNameAware) bean).setBeanName(beanName);
        }
        if (bean instanceof BeanClassLoaderAware) {
            ((BeanClassLoaderAware) bean).setBeanClassLoader(bcl);
            
        }
        if (bean instanceof BeanFactoryAware) {
            ((BeanFactoryAware) bean).setBeanFactory(AbstractAutowireCapableBeanFactory.this);
        }
    }
}
  • 第二次注入
    • EnvironmentAware：注入 Enviroment，一般用于获取配置属性；
    • EmbeddedValueResolverAware：注入 EmbeddedValueResolver（Spring EL解析器），一般用于参数解析；
    • ApplicationContextAware（ResourceLoader、ApplicationEventPublisherAware、MessageSourceAware）：注入 ApplicationContext 容器本身。
private void invokeAwareInterfaces(Object bean) {
    if (bean instanceof EnvironmentAware) {
        ((EnvironmentAware) bean).setEnvironment(this.applicationContext.getEnvironment());
    }
    if (bean instanceof EmbeddedValueResolverAware) {
        ((EmbeddedValueResolverAware) bean).setEmbeddedValueResolver(this.embeddedValueResolver);
    }
    if (bean instanceof ResourceLoaderAware) {
        ((ResourceLoaderAware) bean).setResourceLoader(this.applicationContext);
    }
    if (bean instanceof ApplicationEventPublisherAware) {
        ((ApplicationEventPublisherAware) bean).setApplicationEventPublisher(this.applicationContext);
    }
    if (bean instanceof MessageSourceAware) {
        ((MessageSourceAware) bean).setMessageSource(this.applicationContext);
    }
    if (bean instanceof ApplicationStartupAware) {
        ((ApplicationStartupAware) bean).setApplicationStartup(this.applicationContext.getApplicationStartup());
    }
    if (bean instanceof ApplicationContextAware) {
        ((ApplicationContextAware) bean).setApplicationContext(this.applicationContext);
    }
}
Aware interface Method to override Purpose
ApplicationContextAware void setApplicationContext (ApplicationContext applicationContext) throws BeansException; Interface to be implemented by any object that wishes to be notified of the ApplicationContext that it runs in.
可以向组件中注入IOC容器, 用于获取 ApplicationContext
ApplicationEventPublisherAware void setApplicationEventPublisher (ApplicationEventPublisher applicationEventPublisher); Set the ApplicationEventPublisher that this object runs in.
BeanClassLoaderAware void setBeanClassLoader (ClassLoader classLoader); Callback that supplies the bean class loader to a bean instance.
注入加载当前 bean 的 ClassLoader
BeanFactoryAware void setBeanFactory (BeanFactory beanFactory) throws BeansException; Callback that supplies the owning factory to a bean instance.
注入 当前 BeanFactory 容器 的引用
BeanNameAware void setBeanName(String name); Set the name of the bean in the bean factory that created this bean.
注入当前 bean 对应 beanName
BootstrapContextAware void setBootstrapContext (BootstrapContext bootstrapContext); Set the BootstrapContext that this object runs in.
LoadTimeWeaverAware void setLoadTimeWeaver (LoadTimeWeaver loadTimeWeaver); Set the LoadTimeWeaver of this object’s containing ApplicationContext.
MessageSourceAware void setMessageSource (MessageSource messageSource); Set the MessageSource that this object runs in.
NotificationPublisherAware void setNotificationPublisher (NotificationPublisher notificationPublisher); Set the NotificationPublisher instance for the current managed resource instance.
PortletConfigAware void setPortletConfig (PortletConfig portletConfig); Set the PortletConfig this object runs in.
PortletContextAware void setPortletContext (PortletContext portletContext); Set the PortletContext that this object runs in.
ResourceLoaderAware void setResourceLoader (ResourceLoader resourceLoader); Set the ResourceLoader that this object runs in.
ServletConfigAware void setServletConfig (ServletConfig servletConfig); Set the ServletConfig that this object runs in.
ServletContextAware void setServletContext (ServletContext servletContext); Set the ServletContext that this object runs in.

参考 sring-bean-life-cycle

// 1.容器启动
AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfigOfLifeCycle.class);

// 2.
org.springframework.context.support.AbstractApplicationContext.refresh

// 3. 
org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization

// 4. 
org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons

// 5. 
org.springframework.beans.factory.support.AbstractBeanFactory.getBean(java.lang.String)

// 6.
org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean

// 7.
org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(java.lang.String, org.springframework.beans.factory.ObjectFactory<?>)

// 8.
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(java.lang.String, org.springframework.beans.factory.support.RootBeanDefinition, java.lang.Object[])

// 9.
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean

// 10.
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(java.lang.String, java.lang.Object, org.springframework.beans.factory.support.RootBeanDefinition)

// 11.
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization
        
// 12. 执行初始化方法 initMethod
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods

// 13.
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsAfterInitialization

// 之后循环依赖检查 afterPropertiesSet