spring配置文件中的动态依赖项注入

I need to know how to inject a dependency dynamically in spring configuration file. For an example I have a business logic class called 'Class A'. Inside that class, it handle a method called 'doSomething()'. According to the application this method can perform in two different ways(two type of implementations for same method). So I have declared a interface called 'Manager' with this method and create two implementation classes for same interface. Lets called them 'Impl1' and 'Impl2' which implement interface 'Manager'.I need to know how to inject a dependency dynam