How to use Localstorage_android in Android WebView

I use HTML5 's Localstorage on Android.
Why can't you read it or not?
A lot of search on the internet has no effect

Mainwebview = (webview) This.findviewbyid (R.id.mainwebview);
    WebSettings settings = Mainwebview.getsettings ();
    Settings.setjavascriptenabled (true);
    Settings.setallowfileaccess (true); 
    Settings.setdatabaseenabled (true);
     String dir = This.getapplicationcontext (). Getdir ("Database", Context.mode_private). GetPath ();  
    Settings.setdatabasepath (dir);  
    Settings.setdomstorageenabled (true);
    Settings.setgeolocationenabled (TRUE);

Solution:

Mwebview.getsettings (). Setdomstorageenabled (true);  
Mwebview.getsettings (). Setappcachemaxsize (1024*1024*8); 
String Appcachepath = Getapplicationcontext (). Getcachedir (). GetAbsolutePath (); 
Mwebview.getsettings (). Setappcachepath (Appcachepath); 
Mwebview.getsettings (). Setallowfileaccess (true); 

Mwebview.getsettings (). Setappcacheenabled (True); 

This test is okay.