譬如說我程序中有一個Spring bean如下，它會被一個自定義的Util普通類（里面都是靜態(tài)方法）所用，

@Component
public class SpringContextUtil implements ApplicationContextAware {

    private static ApplicationContext context = null;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext)
        throws BeansException {
    this.context = applicationContext;
    }

    public static <T> T getBean(String beanName) {
        return (T) context.getBean(beanName);
    }

    public static String getActiveProfile() {
        return context.getEnvironment().getActiveProfiles()[0];
    }
}

那假如這個Spring Bean在Util類初始化后再初始化肯定不行，那么像這種問題，spring是如何解決的？譬如Util類對Spring Bean的SpringContextUtil.getActiveProfile()的調(diào)用會觸發(fā)該bean的初始化？或者因為該bean未初始化，只是SpringContextUtil類加載了，然后因為applicationContext未注入，導(dǎo)致Null pointer Exception?