学步园

 < bean id = "" 

        class = "" > 

        < property name = "" > 

            < ref bean = "" /> 

        </ property > 

        < property name = "" > 

            < ref local = "" /> 

        </ property > 

    </ bean > 

ref bean 是寻找全局中的
bean; ref local 是寻找同一xml文件中的bean,找不到则报错