How to intercept POST data in an android webview

Question

I have an android app that consists of a webview. It needs to allow users to fill in a form on a webpage and then change the data of the form after the user has clicked submit on the form. The form will use the POST request method.

So my question is, how can I intercept the POST data from the form, change it's values, then send it along?

For example: If there's a web form like this...

<form action="http://www.example.com/do.php" method="post">
    <input type="text" name="name" />
    <input type="text" name="email" />
    <input type="submit" />
</form>

If the user enters name = Steve and email = [e-mail] in the form, I want to change the values to name = bob and email = [e-mail] in the android app and have the new POST be sent to http://www.example.com/do.php.

Thanks for your help!

Answer 1

I wrote a library with a special WebViewClient that offers a modified shouldOverrideUrlLoading where you can have access to post data.

https://github.com/KonstantinSchubert/request_data_webviewclient

Unfortunately, my implementation works for XMLHttpRequest (AJAX) requests only. But somebody else drafted already how this would be done for form data: https://github.com/KeejOow/android-post-webview

Between the two repositories, you should be able to find your answer :)

Answer 2

I think you can use shouldInterceptRequest(WebView view, String url) method of WebViewClient, but it is supported in the API's later than 11.

Answer 3

If you are familiar with JavaScript, I would suggest you use JavaScript. I think it's more convenient and easy. This tour tells you how to use JavaScript in a WebView.

Answer 4

I liked the suggestion for public void postUrl(String url, byte[] postData) , but unfortunately it did not work for me.

My solution for just intercepting the POST request:

• have a WebViewClient subclass that is set for WebView
• override public void onPageStarted(WebView view, String url, Bitmap favicon) to examine the request data and act accordingly (as per requirements)

Code excerpt & additional thoughts here: https://stackoverflow.com/a/9493323/2162226

Answer 5

if you are submitting the form using postUrl() method then you can override the postUrl method in your WebView object like this.

 WebView mWebView = new WebView(this){

        @Override
        public void  postUrl(String  url, byte[] postData)
        {
            System.out.println("postUrl can modified here:" +url);
            super.postUrl(url, postData);
        }};
 LinearLayout linearLayout = (LinearLayout) findViewById(R.id.linearLayout);
 linearLayout.addView(mWebView);

Answer 6

overriding onPageStarted callback in your WebView