Minstrel

Introduction

This library brings Android's webview/bridge support very much on par with iOS's JavascriptCore framework. It allows for parameters to be passed to and from Javascript of any type.

ie: This now works when calling from Javascript back to the native app. The app will then execute the callback (2nd parameter) upon completion.

android.updateRecords({ name: "Herbert", age: 22 }, function (status) { updateWebUI(status); });

Usage

• Instead of using a WebView, replace it with an instance of JSWebView.
• To export your objects and methods, continue calling addJavascriptInterface() as you normally would.
• For all exported objects and methods, all parameters should be Strings (see below).
• You'll then need to wrap those parameters with JSValue: ie: JSValue jsParam = JSValue(param);

Example:

Imagine this is called from Javascript ...

android.doSomething(function (n) { return n * n; });

In your Activity ...

  webView.addJavascriptInterface(new Bridge(this, webView), "android");

In the interface you wish to export ...

public class Bridge {
    final Context mContext;
    JSWebView mWebView; // we need the webview in order to call functions.

    Bridge(Context context, JSWebView webView) {
        mContext = context;
        mWebView = webView;
    }

    @JavascriptInterface
    public void doSomething2(String param) {
        // turn the parameter we got into something useful.
        JSValue valueParam = new JSValue(param);

        // is it a function?  if so, lets call it.
        if (valueParam.isFunction()) {
            Object args[] = {5};

            // call said function against mWebView, with the given args.
            // the ValueCallback will be executed once the called function returns.
            valueParam.callFunction(mWebView, args, new ValueCallback<JSValue>() {
                @Override
                public void onReceiveValue(final JSValue value) {
                    // did we actually get back a value?  (ie: not null or undefined)
                    if (value.isValid()) {
                        // do something with your value of 25
                        Log.d("value", value.stringValue());
                    }
                }
            });
        }
    }

}

How does it work?

Essentially it creates a proxy object in Javascript for everything you export, which turns all parameters/returns into JSON. We then pass the JSON to and fro as Strings, decode them, etc. Please have a look at the source and let me know if you have further questions.

Contributions

We appreciate your contributions to all of our projects and look forward to interacting with you via Pull Requests, the issue tracker, via Twitter, etc. We're happy to help you, and to have you help us. We'll strive to answer every PR and issue and be very transparent in what we do.