If it's your first time interacting with Facebook, probably you haven't found many examples in Java, have you?
On my case I'm working with something really simple, I just need to create a simple app that will be configured as Canvas. There are 2 important steps in order to work with Facebook by using Canvas:
1. Authorization
When Facebook calls your webpage (on my case a jhtml using SEAM - it could be a JSP as well), it will send through POST something called signed_request, for more details please read this The signed_request parameter is the concatenation of a HMAC SHA-256 signature string, a period (.), and a base64url encoded JSON object. It looks something like this (without the newlines):
However, in order to play around with JSON object, we need to decode it, and this will do the trick: It's very important to use sun.misc.BASE64Decoder in order to avoid missing few characters when decoding with other classes. Belive me, this save you from a lot of headeaches. I'm a big fan of Commons, however, it didn't work out really good when decoding this JSON object. FYI, this is my method.
2. Authentication
This step is really easy, because based on attributes oauth_token and expires, we have a to make a http call to https://graph.facebook.com/me in order to authenticate into FB.
As result of my http call, by using the JSON object returned, I'm able to get more details about this FB account, such as email, first name, last name, age, languages, among others. The next steps depend how deep you want to go.
Good luck!
On my case I'm working with something really simple, I just need to create a simple app that will be configured as Canvas. There are 2 important steps in order to work with Facebook by using Canvas:
1. Authorization
When Facebook calls your webpage (on my case a jhtml using SEAM - it could be a JSP as well), it will send through POST something called signed_request, for more details please read this The signed_request parameter is the concatenation of a HMAC SHA-256 signature string, a period (.), and a base64url encoded JSON object. It looks something like this (without the newlines):
vlXgu64BQGFSQrY0ZcJBZASMvYvTHu9GQ0YM9rjPSso . eyJhbGdvcml0aG0iOiJITUFDLVNIQTI1NiIsIjAiOiJwYXlsb2FkIn0
Just by receiving this parameter, it means that you (as facebook user) just authorized this app on your account, otherwise you'll get the classic mesage asking for your permission to use this app. Next, we need to retrieve from the JSON object 2 parameters that we need to do the authentication: oauth_token and expires).
However, in order to play around with JSON object, we need to decode it, and this will do the trick: It's very important to use sun.misc.BASE64Decoder in order to avoid missing few characters when decoding with other classes. Belive me, this save you from a lot of headeaches. I'm a big fan of Commons, however, it didn't work out really good when decoding this JSON object. FYI, this is my method.
2. Authentication
This step is really easy, because based on attributes oauth_token and expires, we have a to make a http call to https://graph.facebook.com/me in order to authenticate into FB.
As result of my http call, by using the JSON object returned, I'm able to get more details about this FB account, such as email, first name, last name, age, languages, among others. The next steps depend how deep you want to go.
Good luck!
