spring social connectivity with Facebook and accessing user data

Question

I have started to work with spring social and following the tutorial from here . and pages that follow. My java file looks like this.

import org.springframework.boot.autoconfigure.EnableAutoConfiguration;

//import org.springframework.boot.SpringApplication;
//import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.social.connect.Connection;
import org.springframework.social.connect.ConnectionFactory;
import org.springframework.social.connect.ConnectionFactoryLocator;
import org.springframework.social.connect.support.ConnectionFactoryRegistry;
import org.springframework.social.facebook.api.Comment;
import org.springframework.social.facebook.api.CommentOperations;
import org.springframework.social.facebook.connect.FacebookConnectionFactory;
import org.springframework.social.facebook.api.Facebook;
import org.springframework.social.facebook.api.impl.FacebookTemplate;
import org.springframework.social.oauth2.AccessGrant;
import org.springframework.social.oauth2.GrantType;
import org.springframework.social.oauth2.OAuth2Operations;
import org.springframework.social.oauth2.OAuth2Parameters;
//import org.springframework.social.UserIdSource;
//import org.springframework.social.connect.ConnectionFactoryLocator;
//import org.springframework.social.connect.ConnectionRepository;
//import org.springframework.social.connect.web.ConnectController;

@Configuration
@EnableAutoConfiguration
@Import(FacebookConfig.class)
@ComponentScan
public class App {

   static private String accessToken = "accesstoken";
   static private String secretKey = "secretkey"; 
   static private String clientId = "clientid";
   public static void main(String[] args) {
        FacebookConnectionFactory connectionFactory = new FacebookConnectionFactory(clientId, secretKey);
        OAuth2Operations oauthOperations = connectionFactory.getOAuthOperations();
        OAuth2Parameters params = new OAuth2Parameters();
        params.setRedirectUri("http://facebook.com");
        String authorizeUrl = oauthOperations.buildAuthorizeUrl(GrantType.IMPLICIT_GRANT, params);
        AccessGrant accessGrant = new AccessGrant(accessToken);
        System.out.println(accessGrant.getAccessToken());
        System.out.println(accessGrant.getExpireTime());
        System.out.println(accessGrant.getScope());
        ConnectionFactoryRegistry registry = new ConnectionFactoryRegistry();
        registry.addConnectionFactory(connectionFactory);
        Facebook facebook = new FacebookTemplate(accessToken);
}

}

When i run this code i get the error as stated. Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.2:exec (default-cli) on project mavenproject3: Command execution failed. Process exited with an error: 1(Exit value: 1) -> [Help 1]

To see the full stack trace of the errors, re-run Maven with the -e switch. Re-run Maven using the -X switch to enable full debug logging.

For more information about the errors and possible solutions, please read the following articles: [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException

When i comment out this line:

Facebook facebook = new FacebookTemplate(accessToken);

It works fine. Can someone suggest me the requisite. I am a newbie so please bear with me.

Answer 1

The URL you mentioned isn't really a tutorial as much as it is a reference. Admittedly, it gets a bit detailed and isn't very helpful for the new user. Duly noted...expect a new tutorial to be written as soon as I get a moment to do so.

Where did you get the value of accessToken? If you didn't get it via an OAuth2 "dance" with Facebook, then it's not going to work.

First, I see you creating a FacebookConnectionFactory to obtain an OAuth2Operations, through which you set a redirect URI, etc, etc..and then build an authorization URL for IMPLICIT grant. There are several things out of sorts there:

• Facebook doesn't support IMPLICIT grant. It only supports authorization code grant and client token grant. Even so, with implicit grant and authorization code grant your app must redirect to Facebook (in a web browser) to obtain permission from the user. Once that's granted, then it will redirect back to your app...speaking of which...
• The redirect URI you set is http://facebook.com . That should be the URL of your application where Facebook will redirect back to after authorization.
• After all of that, you never even use the authorizeUrl...it's just in a String. It wouldn't work even if you did use it, for the reasons already mentioned, but the first 5 or so lines are all for nothing.
• You create a ConnectionFactoryRegistry and register the FacebookConnectionFactory with it...but then you do nothing with the ConnectionFactoryRegistry. That's okay...you almost never need to do anything with it anyway, because it primarily exists as a helper to ConnectController.

There's simply no good way of obtaining a user-oriented access token without the redirect "dance". It's important to get permission from the user you'll be accessing Facebook on behalf of. If it were any easier than that, it'd be way too easy to create an app that spams Facebook and essentially ruins the experience for everyone.

The work of obtaining an access token via that redirect "dance" is handled automatically by the framework using ConnectController. Sure, you can do it yourself if you'd rather, but ConnectController will handle all of that for you.

For lack of a proper tutorial at the moment, I recommend that you have a look at https://github.com/spring-projects/spring-social-samples/tree/master/spring-social-showcase . Also, there's a Spring Boot-oriented version of it at https://github.com/spring-projects/spring-social-samples/tree/master/spring-social-showcase-boot that simplifies the configuration more (albeit, it relies on changes that aren't in an official Spring Boot release yet).