Phonegap Java call to Javascript

Question

I'm using Phonegap to develop an app. I've downloaded a camera plugin, however, I'd like to make a Javascript call from within the plugin.

In the Java file for the camera plugin I have done the following;

private class sendJS extends CordovaActivity {
    public void sendcommand() {
        this.sendJavascript("alert('1337')");
    }
}

@Override
public void onClick(View v) {
    sendJS test = new sendJS();
    test.sendcommand();
}

However, when the onclick is triggered nothing happens...

I've also tried super.sendJavascript() and super.loadUrl() but it didn't work.

Thanks.

You should use the exec() command inside Cordova, see cordova.apache.org/docs/en/3.5.0/… — MBillau
– MBillau, Commented Sep 16, 2014 at 17:07
@MBillau: Looks like that is in the Javascript side, not the Java side. The code he has above is the Java side. — Dark Falcon
– Dark Falcon, Commented Sep 16, 2014 at 17:10
@DarkFalcon, you are right. I'm trying to do exactly the opposite of that... — Thomas
– Thomas, Commented Sep 16, 2014 at 21:06

Andrew Barber · Accepted Answer · 2014-09-29 02:44:48Z

You have two ways to comunicate to your javascript code. The first one is injecting code to webview via .loadUrl(...) method. The second one is via a callback in response to a javascript->native-plugin(java) call.

You can see callback response in execYourJavaMethod() and injecting in sendcommand()

private class sendJS extends CordovaActivity {
  @Override
  public boolean execute(String action, JSONArray args, CallbackContext callbackContext) throws JSONException {
    // Implement here your calls from javascript
    boolean result = false;

    if ("yourJavaMethod".equals(action)) {
      JSONObject options = args.optJSONObject(0);
      result = execYourJavaMethod(options, callbackContext);
    }

    return result;
  }

  public boolean execYourJavaMethod(JSONObject options, CallbackContext callbackContext) {
    // This will inject an event to your javascript code
    this.sendcommand();

    boolean iWantToCallSuccessCallbackWithData = false;
    if (iWantToCallSuccessCallbackWithData) {
      // This will call your success callback with some data
      callbackContext.sendPluginResult(new PluginResult(PluginResult.Status.OK, "Your data back to javascript"));

    } else {
      // This will call the success callback with no data
      callbackContext.success();
    }

    return true;
  }

  public void sendcommand() {
    String event = String.format("javascript:cordova.fireDocumentEvent('yourEventHere', { 'param1': '%s' });", "some string for param1");
    this.webView.loadUrl(event);
  }
}

From javascript side you should register the listener for your event:

document.addEventListener('yourEventHere', function(e) {
  alert(JSON.stringify(e));
});

To comunicate to your Java plugin:

myPlugin.doSomethingInJava = function (successCallback, failureCallback) {
  cordova.exec(successCallback, failureCallback, 'sendJS', 'yourJavaMethod', []);
};

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