Google OAuth 2.0 Scribe Java Example

Google OAuthServiceConfig and OAuthServiceProvider Bean

<bean id="gdServiceConfig" class="com.example.oauth.OAuthServiceConfig">
		<constructor-arg value="xxx.apps.googleusercontent.com" />
		<constructor-arg value="xxx"/>
		<constructor-arg value="https://www.example.com/oauth/gd"/>
		<!-- <constructor-arg value="openid profile email https://www.googleapis.com/auth/drive.file"/> -->
		<constructor-arg value="com.example.oauth.GoogleDriveOauthApi"/>
	</bean>
	<bean id="gdServiceProvider" class="com.example.oauth.OAuthServiceProvider">
		<constructor-arg name="config" ref="gdServiceConfig" />
	</bean>
</bean>

Google OAuth Spring MVC Controller

package com.example.oauth.controller;

import static org.springframework.web.context.request.RequestAttributes.SCOPE_SESSION;

import java.util.Map;

import javax.servlet.http.HttpSession;

import org.scribe.model.Token;
import org.scribe.model.Verifier;
import org.scribe.oauth.OAuthService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;
import org.springframework.web.context.request.WebRequest;

import com.example.oauth.OAuthServiceProvider;

@Controller
@RequestMapping("/oauth/gd")
public class GoogleDriveController {

	@Autowired
	@Qualifier("gdServiceProvider")
	private OAuthServiceProvider gdServiceProvider;
	
	private static final Token EMPTY_TOKEN = null;
	
	@RequestMapping(value = "/login-gd", method = RequestMethod.GET)
	public String loginToGoogleDrive(Map<String, Object> map, WebRequest request) {
		OAuthService service = gdServiceProvider.getService();
		String auth = service.getAuthorizationUrl(EMPTY_TOKEN);
		System.out.println("RequestToken: " + auth);
		return "redirect:" + auth;
	}
	
	@RequestMapping(value={""}, method = RequestMethod.GET)
	public String callback(@RequestParam(value="oauth_token", required=false) String oauthToken,
			@RequestParam(value="code", required=false) String oauthVerifier, WebRequest request, Map<String, Object> map) {

		OAuthService service = gdServiceProvider.getService();

		// getting access token
		Verifier verifier = new Verifier(oauthVerifier);
		Token accessToken = service.getAccessToken(EMPTY_TOKEN, verifier);

		// store access token as a session attribute
		request.setAttribute("oauthAccessToken", accessToken, SCOPE_SESSION);

		ServletRequestAttributes attr = (ServletRequestAttributes) RequestContextHolder.currentRequestAttributes();
		HttpSession session = attr.getRequest().getSession(false); //create a new session
		session.setAttribute("accessToken",accessToken);

		return "settings";
	}
}

Google OAuth extends DefaultApi20

package com.example.oauth;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.scribe.builder.api.DefaultApi20;
import org.scribe.extractors.AccessTokenExtractor;
import org.scribe.model.OAuthConfig;
import org.scribe.model.Verb;
import org.scribe.exceptions.OAuthException;
import org.scribe.model.OAuthConstants;
import org.scribe.model.OAuthRequest;
import org.scribe.model.Response;
import org.scribe.model.Token;
import org.scribe.model.Verifier;
import org.scribe.oauth.OAuth20ServiceImpl;
import org.scribe.oauth.OAuthService;
import org.scribe.utils.OAuthEncoder;
import org.scribe.utils.Preconditions;

public class GoogleDriveOauthApi extends DefaultApi20{

	  private static final String AUTHORIZE_URL = "https://accounts.google.com/o/oauth2/auth?response_type=code&client_id=%s&redirect_uri=%s";
	    private static final String SCOPED_AUTHORIZE_URL = AUTHORIZE_URL + "&scope=%s";
	 
	    @Override
	    public String getAccessTokenEndpoint() {
	        return "https://accounts.google.com/o/oauth2/token";
	    }
	    
	    @Override
	    public AccessTokenExtractor getAccessTokenExtractor() {
	        return new AccessTokenExtractor() {
	            
	            @Override
	            public Token extract(String response) {
	                Preconditions.checkEmptyString(response, "Response body is incorrect. Can't extract a token from an empty string");
	 
	                Matcher matcher = Pattern.compile("\"access_token\" : \"([^&\"]+)\"").matcher(response);
	                if (matcher.find())
	                {
	                  String token = OAuthEncoder.decode(matcher.group(1));
	                  return new Token(token, "", response);
	                } 
	                else
	                {
	                  throw new OAuthException("Response body is incorrect. Can't extract a token from this: '" + response + "'", null);
	                }
	            }
	        };
	    }
	 
	    @Override
	    public String getAuthorizationUrl(OAuthConfig config) {
            return String.format(SCOPED_AUTHORIZE_URL, config.getApiKey(),
                    OAuthEncoder.encode(config.getCallback()),
                    OAuthEncoder.encode("openid profile email https://www.googleapis.com/auth/drive.file"));
	    }
	    
	    @Override
	    public Verb getAccessTokenVerb() {
	        return Verb.POST;
	    }
	    
	    @Override
	    public OAuthService createService(OAuthConfig config) {
	        return new GoogleOAuth2Service(this, config);
	    }
	    
	    private class GoogleOAuth2Service extends OAuth20ServiceImpl {
	 
	        private static final String GRANT_TYPE_AUTHORIZATION_CODE = "authorization_code";
	        private static final String GRANT_TYPE = "grant_type";
	        private DefaultApi20 api;
	        private OAuthConfig config;
	 
	        public GoogleOAuth2Service(DefaultApi20 api, OAuthConfig config) {
	            super(api, config);
	            this.api = api;
	            this.config = config;
	        }
	        
	        @Override
	        public Token getAccessToken(Token requestToken, Verifier verifier) {
	            OAuthRequest request = new OAuthRequest(api.getAccessTokenVerb(), api.getAccessTokenEndpoint());
	            switch (api.getAccessTokenVerb()) {
	            case POST:
	                request.addBodyParameter(OAuthConstants.CLIENT_ID, config.getApiKey());
	                request.addBodyParameter(OAuthConstants.CLIENT_SECRET, config.getApiSecret());
	                request.addBodyParameter(OAuthConstants.CODE, verifier.getValue());
	                request.addBodyParameter(OAuthConstants.REDIRECT_URI, config.getCallback());
	                request.addBodyParameter(GRANT_TYPE, GRANT_TYPE_AUTHORIZATION_CODE);
	                break;
	            case GET:
	            default:
	                request.addQuerystringParameter(OAuthConstants.CLIENT_ID, config.getApiKey());
	                request.addQuerystringParameter(OAuthConstants.CLIENT_SECRET, config.getApiSecret());
	                request.addQuerystringParameter(OAuthConstants.CODE, verifier.getValue());
	                request.addQuerystringParameter(OAuthConstants.REDIRECT_URI, config.getCallback());
	                if(config.hasScope()) request.addQuerystringParameter(OAuthConstants.SCOPE, "openid profile email https://www.googleapis.com/auth/drive.file");
	            }
	            Response response = request.send();
	            return api.getAccessTokenExtractor().extract(response.getBody());
	        }
	    }
}