由代码注释可以看出来：

postProcessBeforeInitialization() 会在任何的初始化回调之前调用（实现 InitializingBean 或者 自定义的 init-method）

postProcessAfterInitialization() 会在任何的初始化回调之后调用

public interface BeanPostProcessor {

	/**
	 * Apply this {@code BeanPostProcessor} to the given new bean instance <i>before</i> any bean
	 * initialization callbacks (like InitializingBean's {@code afterPropertiesSet}
	 * or a custom init-method). The bean will already be populated with property values.
	 * The returned bean instance may be a wrapper around the original.
	 * <p>The default implementation returns the given {@code bean} as-is.
	 * @param bean the new bean instance
	 * @param beanName the name of the bean
	 * @return the bean instance to use, either the original or a wrapped one;
	 * if {@code null}, no subsequent BeanPostProcessors will be invoked
	 * @throws org.springframework.beans.BeansException in case of errors
	 * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet
	 */
	@Nullable
	default Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
		return bean;
	}

	/**
	 * Apply this {@code BeanPostProcessor} to the given new bean instance <i>after</i> any bean
	 * initialization callbacks (like InitializingBean's {@code afterPropertiesSet}
	 * or a custom init-method). The bean will already be populated with property values.
	 * The returned bean instance may be a wrapper around the original.
	 * <p>In case of a FactoryBean, this callback will be invoked for both the FactoryBean
	 * instance and the objects created by the FactoryBean (as of Spring 2.0). The
	 * post-processor can decide whether to apply to either the FactoryBean or created
	 * objects or both through corresponding {@code bean instanceof FactoryBean} checks.
	 * <p>This callback will also be invoked after a short-circuiting triggered by a
	 * {@link InstantiationAwareBeanPostProcessor#postProcessBeforeInstantiation} method,
	 * in contrast to all other {@code BeanPostProcessor} callbacks.
	 * <p>The default implementation returns the given {@code bean} as-is.
	 * @param bean the new bean instance
	 * @param beanName the name of the bean
	 * @return the bean instance to use, either the original or a wrapped one;
	 * if {@code null}, no subsequent BeanPostProcessors will be invoked
	 * @throws org.springframework.beans.BeansException in case of errors
	 * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet
	 * @see org.springframework.beans.factory.FactoryBean
	 */
	@Nullable
	default Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
		return bean;
	}

}