16、生命周期-BeanPostProcessor原理

16、生命周期-BeanPostProcessor原理

16.1 打断点运行postProcessBeforeInitialization

可以看到先执行的顺序为：

1. applyBeanPostProcessorsBeforeInitialization
2. invokeInitMethods
3. applyBeanPostProcessorsAfterInitialization

16.2 BeanPostProcessor原理

• 遍历得到容器中所有的BeanPostProcessor ，挨个执行 postProcessBeforeInitialization，一旦返回null，跳出for循环，不会执行后面的BeanPostProcessor

populateBean() 给bean进行属性赋值
initializeBean(){
    applyBeanPostProcessorsBeforeInitialization();
    invokeInitMethods();    // 执行自定义初始化
    applyBeanPostProcessorsAfterInitialization();
}

@Override
public Object applyBeanPostProcessorsBeforeInitialization(Object existingBean, String beanName)
		throws BeansException {

	Object result = existingBean;
	for (BeanPostProcessor processor : getBeanPostProcessors()) {
		Object current = processor.postProcessBeforeInitialization(result, beanName);
		if (current == null) {
			return result;
		}
		result = current;
	}
	return result;
}