有四個：（要學會去檢視spring的api）

1： <T> T getBean(Class<T> requiredType)

Return the bean instance that uniquely matches the given object type, if any.

2： Object getBean(String name)

Return an instance, which may be shared or independent, of the specified bean.

3：<T> T getBean(String name, Class<T> requiredType)

Return an instance, which may be shared or independent, of the specified bean.

4： Object getBean(String name, Object... args)

Return an instance, which may be shared or independent, of the specified bean.