Parsing facebook signed response json - facebook

Question

I have a app of google app engine for for java and it have a facebook form which on submitting send a signed_request to a servlet in our app. We are using following code to unencrypt and convert to a json string
String signedRequest = (String) req.getParameter("signed_request");
String payload = signedRequest.split("[.]", 2)[1];
payload = payload.replace("-", "+").replace("_", "/").trim();
String jsonString = new String(Base64.decodeBase64(payload.getBytes()));
System.out.println("Json is::" + jsonString);
The response looks like
[sakshumweb/3.361739372881481188].: Json is::{"algorithm":"HMAC-SHA256","expires":1347588000,"issued_at":1347584290,"oauth_token":"XXXXX","registration":{"name":"Vik Kumar","first_name":"Vik","last_name":"Kumar","bloodGroup":"B-","gender":"male","birthday":"10/31/1983","email":"vik.ceo\u0040gmail.com","cellPhone":"1234123456","homePhone":"1234123457","officePhone":"1234123458","primaryAddress":"jdfjfgj","area":"jfdjdfj","location":{"name":"Redwood Shores, California","id":103107903062719},"subscribe":true,"eyePledge":false,"reference":"fgfgfgfg"},
"registration_metadata":{"fields":"[{\"name\":\"name\"},{\"name\":\"first_name\"},{\"name\":\"last_name\"}, {\"name\":\"bloodGroup\", \"description\":\"Blood Group\", \"type\":\"select\", \"options\":{\"A+\":\"A+\",\"A-\":\"A-\",\"B+\":\"B+\",\"B-\":\"B-\",\"O+\":\"O+\",\"O-\":\"O-\",\"AB+\":\"AB+\",\"AB-\":\"AB-\",\"A1+\":\"A1+\",\"A1-\":\"A1-\",\"A2+\":\"A2+\",\"A2-\":\"A2-\",\"A1B+\":\"A1B+\",\"A1B-\":\"A1B-\",\"A2B+\":\"A2B+\",\"A2B-\":\"A2B-\",\"HH\":\"Bombay Blood Group\"}}, {\"name\":\"gender\"}, {\"name\":\"birthday\"},{\"name\":\"email\"}, {\"name\":\"cellPhone\", \"description\":\"Cell Number\", \"type\":\"text\"}, {\"name\":\"homePhone\", \"description\":\"Home Number\", \"type\":\"text\"}, {\"name\":\"officePhone\", \"description\":\"Office Number\", \"type\":\"text\"}, {\"name\":\"primaryAddress\", \"description\":\"Primary Address\", \"type\":\"text\"}, {\"name\":\"area\", \"description\":\"Locality/Village/Area\", \"type\":\"text\"},{\"name\":\"location\"}, {\"name\":\"subscribe\", \"description\":\"Subscribe me for the Sakshum activites updates.\", \"type\":\"checkbox\", \"default\":\"checked\"}, {\"name\":\"eyePledge\", \"description\":\"I want to pledge my eyes as well.\", \"type\":\"checkbox\"}, {\"name\":\"reference\", \"description\":\"How you reached to us (Friend, Facebook, google etc.)?\", \"type\":\"text\"}]"},"user":{"country":"us","locale":"en_GB"},"user_id":"875390603"}
So, how do i parse this data to extract the data in registration part of this response?

Answer 1

Since this is a valid JSON, you can use JSON library like Jackson or GSON to parse it.
You can use this example code to print out all registration fields:
JsonNode json = new ObjectMapper().readTree(response);
JsonNode registration_fields = json.get("registration");
Iterator<String> fieldNames = registration_fields.getFieldNames();
while(fieldNames.hasNext()){
String fieldName = fieldNames.next();
String fieldValue = registration_fields.get(fieldName).asText();
System.out.println(fieldName+" : "+fieldValue);
}