/**

     * Initialize the given bean instance, applying factory callbacks

     * as well as init methods and bean post processors.

     * 生成bean实例，并且回调诸如init methods，bean post processors方法

     * <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(final String beanName, final Object bean, @Nullable RootBeanDefinition mbd) {

        if (System.getSecurityManager() != null) {

            AccessController.doPrivileged((PrivilegedAction<Object>) () -> {

                invokeAwareMethods(beanName, bean);

                return null;

            }, getAccessControlContext());

        }

        else {

            // 执行BeanNameAware，BeanClassLoaderAware，BeanFactoryAware接口方法

            invokeAwareMethods(beanName, bean);

        }

        Object wrappedBean = bean;

        if (mbd == null || !mbd.isSynthetic()) {

            // 执行BeanPostProcessor的postProcessBeforeInitialization方法，包括@PostConstruct注解方法

            wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);

        }

        try {

            // 执行InitializingBean的afterPropertiesSet方法，包括init-method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BeanPostProcessor的postProcessAfterInitialization方法

            wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);

        }

        return wrappedBean;

    }