按下F5快捷键进入finishBeanFactoryInitialization方法里面，如下图所示，可以看到一开始有跟类型转换组件有关的东东，这个嘛玩意我们也勿须深究，故略过。

继续按下F6快捷键让程序往下运行，这不是来判断beanFactory是否有值解析器的吗？这一块我们也没必要深究，也略过。

继续按下F6快捷键让程序往下运行，可以看到有跟AspectJ Weaver有关的东东，这些东东我们也没必要深究，也略过。

当程序运行至finishBeanFactoryInitialization方法的最后一行代码时，可以很清楚地从该行代码上的注释看出，这儿是来初始化所有剩下的单实例bean的。

preInstantiateSingletons

// Trigger initialization of all non-lazy singleton beans…

// Trigger post-initialization callback for all applicable beans…

    @Override
    public void preInstantiateSingletons() throws BeansException {
        if (logger.isTraceEnabled()) {
            logger.trace("Pre-instantiating singletons in " + this);
        }
        // Iterate over a copy to allow for init methods which in turn register new bean definitions.
        // While this may not be part of the regular factory bootstrap, it does otherwise work fine.
        List<String> beanNames = new ArrayList<>(this.beanDefinitionNames);
        // Trigger initialization of all non-lazy singleton beans...
        for (String beanName : beanNames) {
            RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
            if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
                if (isFactoryBean(beanName)) {
                    Object bean = getBean(FACTORY_BEAN_PREFIX + beanName);
                    if (bean instanceof FactoryBean) {
                        FactoryBean<?> factory = (FactoryBean<?>) bean;
                        boolean isEagerInit;
                        if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) {
                            isEagerInit = AccessController.doPrivileged(
                                    (PrivilegedAction<Boolean>) ((SmartFactoryBean<?>) factory)::isEagerInit,
                                    getAccessControlContext());
                        }
                        else {
                            isEagerInit = (factory instanceof SmartFactoryBean &&
                                    ((SmartFactoryBean<?>) factory).isEagerInit());
                        }
                        if (isEagerInit) {
                            getBean(beanName);
                        }
                    }
                }
                else {
                    getBean(beanName);
                }
            }
        }
        // Trigger post-initialization callback for all applicable beans...
        for (String beanName : beanNames) {
            Object singletonInstance = getSingleton(beanName);
            if (singletonInstance instanceof SmartInitializingSingleton) {
                SmartInitializingSingleton smartSingleton = (SmartInitializingSingleton) singletonInstance;
                if (System.getSecurityManager() != null) {
                    AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
                        smartSingleton.afterSingletonsInstantiated();
                        return null;
                    }, getAccessControlContext());
                }
                else {
                    smartSingleton.afterSingletonsInstantiated();
                }
            }
        }
    }