Android :: How To Access HTML Form Data POSTed Through A WebView?

I've started to write an app which provides the user with an HTML form via a WebView. As the form is not under my control, the data filled in may be sent as either GET or POST request. My app is required to capture the transported form data, that is, get a hold on what was entered into the form fields. Using an adequate callback from WebViewClient such as onPageLoaded(), it is easy to capture form data from a GET request. However, I cannot find any appropriate method to allow the same for POSTed data, i.e., be able to access the HTTP POST message body containing the form data. Am I missing a relevant callback here or is there simply no way to accomplish the specified goal with the given API (even the latest level 8)?