Spring自问自答系列2Bean生命周期

Z时代
2024-01-10
分类：综合

Spring中bean的声明周期是怎么样的？

Bean初始化

BeanNameAware接口中setBeanName方法说明中说到：

Set the name of the bean in the bean factory that created this bean. Invocked after population of normal bean peoperties but before an init callback such as InitializingBean#afterPropertiesSet()

说明注入属性、invokeAwareMethods、init方法的执行具有先后次序。

注入属性步骤：

doCreateBean:553, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support):
// 该方法注入参数
populateBean(beanName, mbd, instanceWrapper);

属性注入内部实现的话是通过AutowiredAnnotationBeanPostProcessor对象注入参数

通过AbstractAutowireCapableBeanFactory中initializeBean方法部分代码可以判断出BeanPostProcessor中postProcessBeforeInitialization方法是在setBeanName方法之后、init方法前执行：

protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) {
	if (System.getSecurityManager() != null) {
		AccessController.doPrivileged(new PrivilegedAction<Object>() {
			@Override
			public Object run() {
				invokeAwareMethods(beanName, bean);
				return null;
			}
		}, getAccessControlContext());
	} else {
		invokeAwareMethods(beanName, bean);
	}
	Object wrappedBean = bean;
	if (mbd == null || !mbd.isSynthetic()) {
	    // 执行postBeanProcessor的postProcessorBeforeInitialization方法
		wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
	}
	try {
	    // 执行bean的init方法
		invokeInitMethods(beanName, wrappedBean, mbd);
	} catch (Throwable ex) {
		throw new BeanCreationException(
			(mbd != null ? mbd.getResourceDescription() : null),
			beanName, "Invocation of init method failed", ex);
	}
	if (mbd == null || !mbd.isSynthetic()) {
	// 执行postBeanProcessor的postProcessorAfterInitialization方法
		wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
		}
	return wrappedBean;
}