Android - Reading HTML5 localStorage data directly from Java

Question

I have a simple Android app with WebView. WebView is installed to go to a site that uses the localStorage JavaScript function.

I already have my WebSettings suite installed that allows DomStorage:

webSettings.setJavaScriptEnabled(true);
ebSettings.setDomStorageEnabled(true);

String dbPath = this.getApplicationContext().getDir("database", MODE_PRIVATE).getPath();        
webSettings.setDatabasePath(dbPath);

I need a way in which my Java code can read a variable stored using the localStorage mechanism, for example:

JavaScript does this:

    var storage = window.localStorage;
    storage.setItem("name", "Hello World!");

How can I find out the value of "name" from localStorage from Java code?

Answer 1

yes you can read the value of localStorage in java (Android).

use this plugin https://www.npmjs.com/package/cordova-plugin-nativestorage which use their own storage.

-

    NativeStorage.setItem("reference", obj, setSuccess, setError);
    function setSuccess(obj){
    }
    function setError(obj){
    }

Anroid Java :

    SharedPreferences sharedPreferences = getSharedPreferences("MainActivity", MODE_PRIVATE);
    System.out.println("********---------    shared pref values...   " +  sharedPreferences.getString("myid", "no value"));

Answer 2

yourWebView.setWebChromeClient(new WebChromeClient(){
      public boolean onJsAlert(WebView view, String url, String message, JsResult result) {
        Log.d(tag, "That my local storage value =" + message);
        return false;
      };
    });
(...)
    yourWebView.loadURL("javascript:alert(localStorage.getItem(\"name\"))");

Answer 3

webView.addJavascriptInterface(myInterface, "JSInterface");

Javascript

class myInterface
{

    @JavascriptInterface
    public void getVariable(string fromLocalStorage)
    {
    //your code
    }

}

javascript

window.JSInterface.getVariable(localStorage.getItem("variableName"))

Answer 4

To record data:

if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.KITKAT) {
     webView.evaluateJavascript("localStorage.setItem('"+ key +"','"+ val +"');", null);
} else {
     webView.loadUrl("javascript:localStorage.setItem('"+ key +"','"+ val +"');");
}

To read the data:

if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.KITKAT) {
     webView.evaluateJavascript("localStorage.getItem('"+ key +"');", null);
} else {
     webView.loadUrl("javascript:localStorage.getItem('"+ key +"');");
}

And don't forget to enable javascript android WebvView

webView.getSettings().setJavaScriptEnabled(true);