Listen Webview Key Events from software keyboard in Android Activity

Question

Is it possible to handle software keyboard events from a webview in a host Android application?

For example, can my application's Activity listen the typed content in the search field of a webview displaying Google website?

Considering the method described below this would be possible if I overwrite it returning true, but unfortunatelly I was not able to do it. Any ideas?

public boolean shouldOverrideKeyEvent (WebView view, KeyEvent event)

Added in API level 1
Give the host application a chance to handle the key event synchronously. e.g. menu shortcut key     events need to be filtered this way. If return true, WebView will not handle the key event. If return false, WebView will always handle the key event, so none of the super in the view chain will see the key event. The default behavior returns false.

Parameters
view    The WebView that is initiating the callback.
event   The key event.
Returns
True if the host application wants to handle the key event itself, otherwise return false

Answer 1

I think the shouldOverrideKeyEvent method simply tells the system which "window" should be getting notified of key events; this does NOT pass WebView javascript events back to the Activity.

If you need to pass information from a WebView to your Activity, you can use the JavascriptInterface. Note that this is only possible on a website that you control; otherwise it would be a security loophole, providing your app with access to sensitive data.

First, create a class to act as your interface:

class MyJavaScriptInterface{
    //Methods to call via js in the WebView go here
}

Then initialize the interface on your WebView:

mWebView.getSettings().setJavaScriptEnabled(true);
mWebView.addJavascriptInterface(new MyJavaScriptInterface(), "JSInterface");

Now, you said you wanted to pass the typed content from a text field back to the Activity. For that, register an event listener for the text field on blur, which will fire when the field loses focus.

<!-- HTML element to listen for blur -->
<input id="field" type="text" />

<script>
  //Communicate with Javascript Interface
  var jsFieldBlur = function(field){
      //Only call if the interface exists
      if(window.JSInterface){
          window.JSInterface.onFieldBlur(field.id, field.value);
      }
  };

  //Obtain reference to DOM element
  var field = document.getElementById("field");

  //Attach blur listener
  field.addEventListener("blur", function( event ) {
      jsFieldBlur(event.target);   
  }, true);
</script>

Finally, we need to add the onFieldBlur method to the MyJavascriptInterface class so it can be called via javascript. Any methods defined this way must be preceded by @JavascriptInterface in order to be visible to the WebView.

class MyJavaScriptInterface{
    @JavascriptInterface
    public void onFieldBlur(String fieldId, String fieldValue){
        //Do something with value
        Toast.makeText(getContext(), fieldId+"="+fieldValue, Toast.LENGTH_LONG).show();
    }
}