How to get the Routing stack?

[sds311]

I want register the 's backAndroidHandler event , like Following Code:

<Router backAndroidHandler={
(navProps)=>{ console.log(navProps.navigationState); }
} />,

but , this function Not a bit of navProps , why not injection this parameters, so, how I get the navigationState in backAndroidHandler function, how use the backAndroidHandler function at the difference Scenes show to run the defference logic code?