applicationContext.getBean() 方法用来获取Spring容器已经初始化的bean
初始化之后的原型一共有以下几种类型：
Object getBean(String var1) throws BeansException;<T> T getBean(String var1, Class<T> var2) throws BeansException;Object getBean(String var1, Object... var2) throws BeansException;<T> T getBean(Class<T> var1) throws BeansException;<T> T getBean(Class<T> var1, Object... var2) throws BeansException;