android webview localStorage invalid solution

I use localStorage for html5 in android
Why don't you put it in or read it out?
A lot of Internet searches didn't work

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);

Solutions:

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);