JSP code for FB credit callback url - facebook

Question

i am developing a Facebook iframe app with Facebook credit API. i am using FB JavaScript SDK for that. but i am unable to find out any sample code in java or JSP for FB credit callback URL. all i found is te PHP code and i dont know PHP much.. can anyone convert it for me in JSP or Java?
here is the php sample code
**
* Copyright 2004-Present Facebook. All Rights Reserved.
*
* You should reference https://developers.facebook.com/docs/credits/ as you
* familiarize yourself with callback.php. In particular, read all the steps
* under "Credits Tutorial" and "Credits Callback".
*
* Your application needs the following inputs and outputs
*
* #param int order_id
* #param string status
* #param string method
* #param array order_details (JSON-encoded)
*
* #return array A JSON-encoded array with order_id, next_state
* (optional: error code, comments)
*/
// Enter your app information below
$app_secret = '<app_secret>';
// Prepare the return data array
$data = array('content' => array());
// Parse the signed_request to verify it's from Facebook
$request = parse_signed_request($_REQUEST['signed_request'], $app_secret);
if ($request == null) {
// Handle an unauthenticated request here
}
// Grab the payload
$payload = $request['credits'];
// Retrieve all params passed in
$func = $_REQUEST['method'];
$order_id = $payload['order_id'];
if ($func == 'payments_status_update') {
// Grab the order status
$status = $payload['status'];
// Write your apps logic here for validating and recording a
// purchase here.
//
// Generally you will want to move states from `placed` -> `settled`
// here, then grant the purchasing user's in-game item to them.
if ($status == 'placed') {
$next_state = 'settled';
$data['content']['status'] = $next_state;
}
// Compose returning data array_change_key_case
$data['content']['order_id'] = $order_id;
} else if ($func == 'payments_get_items') {
// remove escape characters
$order_info = stripcslashes($payload['order_info']);
$item_info = json_decode($order_info, true);
if ($item_info == "abc123") {
// Per the credits api documentation, you should pass in an item
// reference and then query your internal DB for the proper
// information. Then set the item information here to be
// returned to facebook then shown to the user for confirmation.
$item['title'] = 'BFF Locket';
$item['price'] = 1;
$item['description'] = 'This is a BFF Locket...';
$item['image_url'] = 'https://www.facebook.com/images/gifts/21.png';
$item['product_url'] = 'https://www.facebook.com/images/gifts/21.png';
} else {
// For the sake of the sample, we will default to this item if
// the `order_info` reference passed from your JS call is not matched
// above.
$item['title'] = 'A Facebook Hat';
$item['price'] = 1;
$item['description'] = 'The coolest hat you\'ve ever seen.';
$item['image_url'] = 'https://www.facebook.com/images/gifts/740.png';
$item['product_url'] = 'https://www.facebook.com/images/gifts/740.png';
}
// Put the associate array of item details in an array, and return in the
// 'content' portion of the callback payload.
$data['content'] = array($item);
}
// Required by api_fetch_response()
$data['method'] = $func;
// Send data back
echo json_encode($data);
// You can find the following functions and more details
// on https://developers.facebook.com/docs/authentication/canvas.
function parse_signed_request($signed_request, $app_secret) {
list($encoded_sig, $payload) = explode('.', $signed_request, 2);
// Decode the data
$sig = base64_url_decode($encoded_sig);
$data = json_decode(base64_url_decode($payload), true);
if (strtoupper($data['algorithm']) !== 'HMAC-SHA256') {
error_log('Unknown algorithm. Expected HMAC-SHA256');
return null;
}
// Check signature
$expected_sig = hash_hmac('sha256', $payload, $app_secret, $raw = true);
if ($sig !== $expected_sig) {
error_log('Bad Signed JSON signature!');
return null;
}
return $data;
}
function base64_url_decode($input) {
return base64_decode(strtr($input, '-_', '+/'));
}

Answer 1

One sample, I will link more as I get.
https://github.com/facebook/facebook-android-sdk
http://code.google.com/p/facebook-java-sdk/