Facebook API

FaceBook API lets you create and manage your own ads on Facebook programmatically

DownLoad Facebook jar
To work in JAVA Download - facebook-java-api-3.0.2-bin.zip

Inlcuded the jar in the class path and try to access the class in the jar

IDE
Eclipse - Version: 3.4.0


Get the API key & Application Secret

To start your work with Facebook API, You need to get the
API key & Application Key.

You need to get register your applications in this page http://www.facebook.com/developers/apps.php using Facebook account.

Necessary fields to be entered as follows
In Basic - Include the developers name .Who will be involving in developing the application.
In Canvas –Give the callback url of your application


We can start coding the application now.

Create the Twitter object & get the request token by passing the application Consumer key & secret.

To get the user client

FacebookJsonRestClient class is used for getting user client returns the object in JSON format.

FacebookJsonRestClient userClient =getUserClientsession);

public static FacebookJsonRestClient.getUserClient(HttpSession session) { 

  return (FacebookJsonRestClient)session.getAttribute(FACEBOOK_USER_CLIENT); 

}

User session doesn't have a Facebook API client setup yet.

Pass the API key & Application secret to get the valid userclient
And store it in a session.

     userClient = new FacebookJsonRestClient(api_key, secret); 

     session.setAttribute(FACEBOOK_USER_CLIENT, userClient);

Pass the Facebook url with your api key & required permission redirect the call.

You can check the permission available in Facebook .

 facebook = new FacebookWebappHelper(req, res, api_key, secret); 

 nextPage = req.getRequestURI();

 nextPage = nextPage.substring(nextPage.indexOf("/", 1) + 1); 

 //cut out the first /, the context path and the 2nd / 

 System.out.println(nextPage);

 boolean redirectOccurred = facebook.requireLogin(nextPage);                   

if(redirectOccurred){

         res.sendRedirect("http://www.facebook.com/login.php?api_key=dbfc65d0e72f5c103gg0gfgd8c5&connect_display=popup&v=1.0&next=http://www.facebook.com/connect/login_success.html&cancel_url=http://www.facebook.com/connect/login_failure.html&fbconnect=true&return_session=true&session_key_only=true&req_perms=read_stream,publish_stream,offline_access,sms,email,user_location");

return; 

  }

After execution of the above code.It request you enter the Facebook username & password.

Get the auth_token

String authToken=request.getParameter("auth_token");         

By passing this authToken to the client you can start working on the functionalities like getting friends ,knowing user details etc.,

You can check the functionalities available in the FacebookJsonRestClient in this link
http://developers.facebook.com/docs/reference/rest/

Functions
To know the current user id

Long  facebookUserID = userClient.users_getLoggedInUser();

To get friends Id’s

JSONArray arrayObj = (JSONArray)userClient.friends_get();

Get the id’s from Array & store it in a list

List userIds = new ArrayList();

for(int i=0;i try {								

   userIds.add((arrayObj.getString(i));

 } catch (JSONException e) {

	e.printStackTrace();

 }

}

Set the necessary fields in the ProfileField,that you need from a
User.

EnumSet fields = EnumSet.of (                  	            com.google.code.facebookapi.ProfileField.NAME,                  	            com.google.code.facebookapi.ProfileField.PIC,                                        com.google.code.facebookapi.ProfileField.CURRENT_LOCATION, com.google.code.facebookapi.ProfileField.FIRST_NAME, com.google.code.facebookapi.ProfileField.LAST_NAME);

To get the user details

  	                                            

  JSONArray userArray = null;

   try {

	userArray = client.users_getInfo(userIds, fields);

       } catch (FacebookException e1) {	

        e1.printStackTrace();

       }

       for(int i=0;i< userArray.length();i++){

   try {						

	  for (int j = 0; j < userArray.length(); j++) {

           JSONObject obj = userArray.getJSONObject(j);

           System.out.println("User Id"+obj.getString("uid"));

           System.out.println("Pic url "+obj.getString("pic"));

           System.out.println("Name"+obj.getString("first_name")  

           +" "+obj.getString "last_name"));

         }

       } catch (JSONException e) {

          e.printStackTrace();}

     }	

To update the status of the current user
Check whether the user having the permissions & than try the functions

if (userClient.users_hasAppPermission(Permission.STATUS_UPDATE)){

userClient.users_setStatus("Status-Developing Facebook apps in Java!", false);

}

To Publish the stream for the current user

if(userClient.users_hasAppPermission(Permission.PUBLISH_STREAM)){

userClient.stream_publish("Stream-Publish-Wall written using Facebook API !", null, null, null, null);

}

To post the link to single /Group of user

userClient.links_post(Long.parseLong("Give the UserID"), "www.kyyba.com", "IT Recruitment");