BeanPostProcessor在显示调用初始化方法前修改bean详解

public interface BeanPostProcessor {
    /**
     * 在bean实例的初始化方法（例如InitializingBean的afterPropertiesSet或自定义的init-method）回调之前，
     * spring会应用此方法到bean实例上。一般用于bean实例的属性值的填充
     */
    @Nullable
    default Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        return bean;
    }
    /**
     * 在bean实例的初始化方法（例如InitializingBean的afterPropertiesSet或自定义的init-method）回调之后，
     * spring会应用此方法到bean实例上。
     * 在有FactoryBean时，此方法会在FactoryBean实例与FactoryBean的目标对象创建时各调用一次
     */
    @Nullable
    default Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        return bean;
    }
}

@Component
public class MyBeanPostProcessor implements BeanPostProcessor {
    public MyBeanPostProcessor () {
        System.out.println("MyBeanPostProcessor 实例化......");
    }
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("spring中bean实例:" + beanName + " 初始化之前处理......");
        return bean;
    }
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("spring中bean实例:" + beanName + " 初始化之后处理......");
        return bean;
    }
}