/**
     * Initialize the given bean instance, applying factory callbacks
     * as well as init methods and bean post processors.
     * <p>Called from {@link #createBean} for traditionally defined beans,
     * and from {@link #initializeBean} for existing bean instances.
     * @param beanName the bean name in the factory (for debugging purposes)
     * 
 
@param bean the new bean instance we may need to initialize
     * @param mbd the bean definition that the bean was created with
     * (can also be {@code null}, if given an existing bean instance)
     * @return the initialized bean instance (potentially wrapped)
     * @see BeanNameAware
     * @see
 
 BeanClassLoaderAware
     * @see BeanFactoryAware
     * @see #applyBeanPostProcessorsBeforeInitialization
     * @see #invokeInitMethods
     * @see #applyBeanPostProcessorsAfterInitialization
     */
    protected Object initializeBean(String beanName, Object bean, @Nullable RootBeanDefinition mbd) {
        
 
if (System.getSecurityManager() != null) {
            AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
                invokeAwareMethods(beanName, bean);
                return null;
            }, getAccessControlContext());
        }
        else {
            invokeAwareMethods(beanName, bean);
        }

        Object wrappedBean = bean;
        if (mbd == null || !mbd.isSynthetic()) {
            wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
        }

        try {
　　　　　　　 //#1  先去執行 實現了 InitializingBean 介面的方法
            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()) {
　　　　　　　　//#2. 呼叫 bean 的後置處理器的 after方法
            wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
        }

        return wrappedBean;
    }