Developing Social Login Using Rest Fb

This is an implementation tutorial on how we can use REST FB to enable facebook social login on our web application.

Basically, it's a project created from javaee7-war template.

To run this app you need to set up a Facebook application with callback url=/oath_callback

pom.xml - we need to define the rest fb dependency which is a java library for logging in facebook.

<dependency>
 <groupId>com.restfb</groupId>
 <artifactId>restfb</artifactId>
 <version>2.9.0</version>
</dependency>

<dependency>
 <groupId>org.jboss.spec.javax.servlet</groupId>
 <artifactId>jboss-servlet-api_3.0_spec</artifactId>
 <version>1.0.2.Final</version>
</dependency>

Callback Servlet -

package com.broodcamp.restfb.servlet;

import java.io.IOException;

import javax.inject.Inject;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.broodcamp.restfb.provider.FacebookProvider;
import com.restfb.DefaultFacebookClient;
import com.restfb.FacebookClient;
import com.restfb.Parameter;
import com.restfb.Version;
import com.restfb.types.User;

@WebServlet("/oath_callback")
public class OauthCallbackServlet extends HttpServlet {

 private static final long serialVersionUID = 4400146595698418400L;

 private static Logger log = LoggerFactory.getLogger(OauthCallbackServlet.class);

 @Inject
 private FacebookProvider facebookProvider;

 private String code;

 @Override
 public void service(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
  code = req.getParameter("code");
  if (code == null || code.equals("")) {
   throw new RuntimeException("ERROR: Didn't get code parameter in callback.");
  }
  String accessToken = facebookProvider.obtainAccessToken(code);
  FacebookClient facebookClient = new DefaultFacebookClient(accessToken, Version.LATEST);
  User facebookUser = facebookClient.fetchObject("me", User.class, Parameter.with("fields", "email,first_name,last_name,birthday"));
  log.debug("FB User firstName={}, lastName={}, email={}, birthday={}", facebookUser.getFirstName(), facebookUser.getLastName(), facebookUser.getEmail(),
    facebookUser.getBirthday());

  RequestDispatcher dispatcher = req.getRequestDispatcher("account.jsf?accessToken=" + accessToken);
  dispatcher.forward(req, res);
 }
}

Facebook Provider - Provider class for initializing the facebook api.

package com.broodcamp.restfb.provider;

import javax.annotation.PostConstruct;
import javax.ejb.Singleton;
import javax.ejb.Startup;

import com.restfb.DefaultFacebookClient;
import com.restfb.FacebookClient;
import com.restfb.FacebookClient.AccessToken;
import com.restfb.Version;
import com.restfb.scope.FacebookPermissions;
import com.restfb.scope.ScopeBuilder;

@Singleton
@Startup
public class FacebookProvider {

 private String appId = "xxx";
 private String appSecret = "yyy";
 private String redirectUrl = "http://localhost:8080/restfb-demo/oauth_callback";
 private String loginDialogUrlString;

 @PostConstruct
 private void init() {
  ScopeBuilder scopeBuilder = new ScopeBuilder();
  scopeBuilder = scopeBuilder.addPermission(FacebookPermissions.EMAIL);
  scopeBuilder = scopeBuilder.addPermission(FacebookPermissions.PUBLIC_PROFILE);

  FacebookClient client = new DefaultFacebookClient(Version.LATEST);
  loginDialogUrlString = client.getLoginDialogUrl(appId, redirectUrl, scopeBuilder);
 }

 public String getAuthUrl() {
  return loginDialogUrlString;
 }

 public String obtainAccessToken(String verificationCode) {
  FacebookClient client = new DefaultFacebookClient(Version.LATEST);
  AccessToken accessToken = client.obtainUserAccessToken(appId, appSecret, redirectUrl, verificationCode);

  return accessToken.getAccessToken();
 }
}

Repository is available at: https://github.com/czetsuya/RESTFB-Demohttps://github.com/czetsuya/RESTFB-Demo