Thursday, March 27, 2014

android java code read javascript stored values

http://stackoverflow.com/questions/18213895/android-service-reads-localstorage

I have developed a PhoneGap application for Android. The application is composed by the webapp(HTML/jQuery) and a background service (Java code) that's started by the webapp.
This webapp writes to window.localStorage like
    <script>
       window.localStorage.setItem("name","MyName");
    </script>
Is it possible to read this name that is in the localStorage from my Java code?
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This is possible. To execute JavaScript and get response you can do as follows:
Define JavaScript callback interface in your code:
class MyJavaScriptInterface {
    public void someCallback(String jsResult) {
         // this will be passed the local storage name variable
    }
}
Attach this callback to your WebView:
MyJavaScriptInterface javaInterface = new MyJavaScriptInterface();
webView.addJavascriptInterface(javaInterface, "HTMLOUT");
Run your JavaScript calling window.HTMLOUT.someCallback from the script:
webView.loadUrl("javascript:( function () { var name = window.localStorage['name']; window.HTMLOUT.someCallback(name); } ) ()");
Note - window.localStorage['name'] is the same as window.localStorage.getItem('name')
You might need to use super.webView.addJavascriptInterface or super.addJavascriptInterface to add the interface. You might need to use super.webView.loadUrl or super.loadUrl to invoke this. It all depends on where you are going to be calling these from.


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