如果在單例beanA裏引入多例beanB，那麼實際上引入的B還是一個，因爲單例A初始化的時候只創建了一次，自然也只引了一次B。
如果想正確使用多例B，應當使用applicationContext.getBean(XXX.class);工具類來獲取。
以下是spring官方文檔。
1.5.3. Singleton Beans with Prototype-bean Dependencies
When you use singleton-scoped beans with dependencies on prototype beans, be aware that dependencies are resolved at instantiation time. Thus, if you dependency-inject a prototype-scoped bean into a singleton-scoped bean, a new prototype bean is instantiated and then dependency-injected into the singleton bean. The prototype instance is the sole instance that is ever supplied to the singleton-scoped bean.
However, suppose you want the singleton-scoped bean to acquire a new instance of the prototype-scoped bean repeatedly at runtime. You cannot dependency-inject a prototype-scoped bean into your singleton bean, because that injection occurs only once, when the Spring container instantiates the singleton bean and resolves and injects its dependencies. If you need a new instance of a prototype bean at runtime more than once, see Method Injection