Working with Google APIs

client.properties

clientId=Enter Client ID

GoogleAuthCode.java

package com.netiq;

import java.awt.Desktop;
import java.awt.Desktop.Action;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.net.URI;
import java.net.URLEncoder;
import java.util.Properties;

import com.google.api.client.extensions.jetty.auth.oauth2.LocalServerReceiver;
import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;

public class GoogleAuthCode {

	public static final String APPLICATION_JSON = "application/json";
	public static final String AUTHORIZATION = "Authorization";
	public static final String CONTENT_TYPE = "Content-Type";

	public static final String ACCOUNT_CHOOSER_URL = "https://accounts.google.com/AccountChooser?service=lso&continue=";
	public static final String REDIRECT_URI = "http://localhost/Callback";
	public static final String OAUTH_URL = "https://accounts.google.com/o/oauth2/auth?";
	
	public static final String SCOPE = "https://www.googleapis.com/auth/admin.directory.user";
	
	private static String _clientId = null;
	
	/**
	 * <pre>	 
		 GET https://accounts.google.com/o/oauth2/auth?
		   scope=https://www.googleapis.com/auth/admin.directory.user&
		   redirect_uri=https://localhost/Callback&
		   response_type=code&
		   client_id=430723156037-c3149idj1vhnqaotri5o5qem9prmm1hd.apps.googleusercontent.com&
		   access_type=offline
	 * </pre>
	 * @param redirectUri
	 * @return
	 * @throws UnsupportedEncodingException
	 */
	private static String getAuthUri(String redirectUri)
			throws UnsupportedEncodingException {
		String responseType = "code";
		String accessType = "offline";
		StringBuilder uriBuilder = new StringBuilder(OAUTH_URL);

		uriBuilder.append("response_type=").append(responseType).append("&");
		uriBuilder.append("scope=").append(URLEncoder.encode(SCOPE, "UTF-8"))
				.append("&");
		uriBuilder.append("redirect_uri=")
				.append(URLEncoder.encode(redirectUri, "UTF-8")).append("&");
		uriBuilder.append("client_id=").append(_clientId).append("&");
		uriBuilder.append("accessType=").append(accessType);
		
		return uriBuilder.toString();
	}
	
	private static void getProperties() throws IOException {
		Properties prop = loadPropertiesAsResource();
		_clientId = prop.getProperty("clientId");
	}
	
	private static void invokeBrowser(String url) throws IOException {
		if (Desktop.isDesktopSupported()) {
			Desktop deskTop = Desktop.getDesktop();
			if (deskTop.isSupported(Action.BROWSE)) {
				System.out.println("Attempting to browse to " + url + " ...");
				deskTop.browse(URI.create(url));
			}
		}
	}
	
	/**
	 * @see <a
	 *      href="http://stackoverflow.com/questions/333363/loading-a-properties-file-from-java-package">Loading
	 *      a properties file from Java package</a>
	 * @return
	 * @throws IOException
	 */
	private static Properties loadPropertiesAsResource() throws IOException {
		Properties prop = new Properties();
		InputStream in = GoogleAuthCode.class
				.getResourceAsStream("client.properties");
		prop.load(in);
		in.close();
		return prop;
	}
	
	/**
	 * Authenticate to Google Apps using OAuth 2.
	 * 
	 * @param args
	 * @throws IOException
	 */
	public static void main(String[] args) throws IOException {

		getProperties();

		// Google will call me back at the redirect URL. Set up a listener.
		LocalServerReceiver receiver = new LocalServerReceiver();
		String redirectUri = receiver.getRedirectUri();
		System.out.println("Local receiver listening on port "
				+ receiver.getPort());
		
		// Make sure to grant the token as an admin user. In my case,
		// ghays@accessreview.net.
		System.out.println("(1) Request authentication using OAuth 2.");
				
		String authUri = getAuthUri(redirectUri);
		System.out.println("Making request to authorization URI: "
				+ authUri.toString());
		System.out.println("Redirect URI: " + redirectUri);

		// (1) Authorize
		Client client = Client.create();
		WebResource wr = client.resource(authUri);
		ClientResponse response = wr.header(CONTENT_TYPE, APPLICATION_JSON)
				.get(ClientResponse.class);
		int status = response.getStatus();
		System.out.println("HTTP Response Status: " + status);
		
		// Launch the Google Account Chooser. Of the form:
		// https://accounts.google.com/AccountChooser?service=lso&continue=[authorizeurl]
		//
		// See http://stackoverflow.com/questions/14384354/force-google-account-chooser
		String chooserUri = ACCOUNT_CHOOSER_URL + URLEncoder.encode(authUri, "UTF-8");
		invokeBrowser(chooserUri);

		// Receive authorization code.
		System.out.println("Waiting for the code...");
		String code = receiver.waitForCode();
		receiver.stop(); // TODO - Put this in a try/finally.
		System.out.println("Google authorization code: " + code);
		
		// TODO - Can we persist the authorization code?
	}
	
	/**
	 * <pre>
	 	2015-04-30 16:57:08.322:INFO::Logging to STDERR via org.mortbay.log.StdErrLog
		2015-04-30 16:57:08.323:INFO::jetty-6.1.26
		2015-04-30 16:57:08.346:INFO::Started SocketConnector@localhost:14975
		Local receiver listening on port 14975
		(1) Request authentication using OAuth 2.
		Making request to authorization URI: https://accounts.google.com/o/oauth2/auth?response_type=code&scope=https%3A%2F%2Fwww.googleapis.com%2Fauth%2Fadmin.directory.user&redirect_uri=http%3A%2F%2Flocalhost%3A14975%2FCallback&client_id=430723156037-c3149idj1vhnqaotri5o5qem9prmm1hd.apps.googleusercontent.com&accessType=offline
		Redirect URI: http://localhost:14975/Callback
		HTTP Response Status: 200
		Attempting to browse to https://accounts.google.com/AccountChooser?service=lso&continue=https%3A%2F%2Faccounts.google.com%2Fo%2Foauth2%2Fauth%3Fresponse_type%3Dcode%26scope%3Dhttps%253A%252F%252Fwww.googleapis.com%252Fauth%252Fadmin.directory.user%26redirect_uri%3Dhttp%253A%252F%252Flocalhost%253A14975%252FCallback%26client_id%3D430723156037-c3149idj1vhnqaotri5o5qem9prmm1hd.apps.googleusercontent.com%26accessType%3Doffline ...
		Waiting for the code...
		2015-04-30 16:57:15.034:INFO::Stopped SocketConnector@localhost:14975
		Google authorization code: 4/5BIHWBuGQWLoOjjcrSMR8L8GnySSea1q9QkNBHl0gUU.AkyzX7Xet3UaPm8kb2vw2M0D2qoYmgI
	 * </pre>
	 */
}

GoogleToken.java

package org.gkh.test;

import java.awt.Desktop;
import java.awt.Desktop.Action;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.net.URI;
import java.net.URLEncoder;
import java.util.Properties;

import org.codehaus.jettison.json.JSONException;
import org.codehaus.jettison.json.JSONObject;

import com.google.api.client.extensions.jetty.auth.oauth2.LocalServerReceiver;
import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;

public class GoogleToken {

	public static final String APPLICATION_ENCODED = "application/x-www-form-urlencoded";
	public static final String APPLICATION_JSON = "application/json";
	public static final String AUTHORIZATION = "Authorization";
	public static final String CONTENT_TYPE = "Content-Type";

	public static final String ACCOUNT_CHOOSER_URL = "https://accounts.google.com/AccountChooser?service=lso&continue=";
	public static final String REDIRECT_URI = "http://localhost/Callback";
	public static final String OAUTH_URL = "https://accounts.google.com/o/oauth2/auth?";
	
	public static final String SCOPE = "https://www.googleapis.com/auth/admin.directory.user";
	
	private static String _clientId = null;
	
	private String _redirectUri = null;
	private String _scope = null;
	
	private LocalServerReceiver _receiver = null;
	
	private Client _client = null;
	private WebResource _webResource = null;
	private ClientResponse _response = null;
	
	// Discussions on whether or not to throw an exception in a constructor. The
	// guidance is to not produce a partially constructed object that may be
	// subclassed and abused.
	// http://stackoverflow.com/questions/6086334/is-it-good-practice-to-make-the-constructor-throw-an-exception
	// http://stackoverflow.com/questions/1371369/can-constructors-throw-exceptions-in-java/1373419#1373419
	// http://stackoverflow.com/questions/7532078/java-exception-in-constructors-problematic-or-not
	// http://www.oracle.com/technetwork/java/seccodeguide-139067.html#7
	public GoogleToken(String scope, String propertyFileName) throws IOException {
		_scope = scope;
		init(propertyFileName);
	}
	
	public GoogleToken() throws IOException {
		_scope = SCOPE;
		init(null);
	}

	public String connect() throws IOException {
		String authUri = getAuthUri();
		System.out.println("Making request to authorization URI: "
				+ authUri.toString());
		System.out.println("Redirect URI: " + _redirectUri);
		
		// (1) Authorize
		_client = Client.create();
		_webResource = _client.resource(authUri);
		_response = _webResource.header(CONTENT_TYPE, APPLICATION_JSON).get(
				ClientResponse.class);
		int status = _response.getStatus();
		System.out.println("HTTP Response Status: " + status);
		
		String code = null;
		
		if (status == 200) {
			// Launch the Google Account Chooser. Of the form:
			// https://accounts.google.com/AccountChooser?service=lso&continue=[authorizeurl]
			// See http://stackoverflow.com/questions/14384354/force-google-account-chooser
			String chooserUri = ACCOUNT_CHOOSER_URL
					+ URLEncoder.encode(authUri, "UTF-8");
			invokeBrowser(chooserUri);

			// Receive authorization code.
			System.out.println("Waiting for the code...");
			code = _receiver.waitForCode();
			_receiver.stop(); // TODO - Put this in a try/finally.
			System.out.println("Google authorization code: " + code);
		}
		
		// TODO - Can we persist the authorization code?
		return code;
	}
	
	public JSONObject exchangeCodeForToken(String code) throws JSONException,
			UnsupportedEncodingException {
		String OAUTH_TOKEN_URL = "www.googleapis.com/oauth2/v3/token";
		String clientSecret = "WA5hqvXVh8pnvjrbCbkHmCIC";
		String tokenUrl = "https://" + OAUTH_TOKEN_URL;

		StringBuilder payloadBuilder = new StringBuilder("code=").append(code);
		payloadBuilder.append("&client_id=").append(_clientId);
		payloadBuilder.append("&client_secret=").append(clientSecret);
		payloadBuilder.append("&redirect_uri=").append(
				URLEncoder.encode(_redirectUri, "UTF-8"));
		payloadBuilder.append("&grant_type=").append("authorization_code");
		payloadBuilder.append("&access_type=").append("offline");
		System.out.println("(2) Exchange authorization code for a token.");
		System.out.println("Making request to " + tokenUrl);

		_webResource = _client.resource(tokenUrl);
		_response = _webResource.header(CONTENT_TYPE, APPLICATION_ENCODED)
				.entity(payloadBuilder.toString()).post(ClientResponse.class);
		int status = _response.getStatus();
		JSONObject jsonResponse = null;
		
		if (status == 200) {
			jsonResponse = _response.getEntity(JSONObject.class);
			System.out.println("Response Status: " + status);
			System.out.println("Token:\n" + jsonResponse.toString(2));
		}
		
		return jsonResponse;
	}
	
	/**
	 * <pre>	 
		 GET https://accounts.google.com/o/oauth2/auth?
		   scope=https://www.googleapis.com/auth/admin.directory.user&
		   redirect_uri=https://localhost/Callback&
		   response_type=code&
		   client_id=430723156037-c3149idj1vhnqaotri5o5qem9prmm1hd.apps.googleusercontent.com&
		   access_type=offline
	 * </pre>
	 * @return
	 * @throws UnsupportedEncodingException
	 */
	private String getAuthUri()
			throws UnsupportedEncodingException {
		String responseType = "code";
		String accessType = "offline";
		StringBuilder uriBuilder = new StringBuilder(OAUTH_URL);

		uriBuilder.append("response_type=").append(responseType).append("&");
		uriBuilder.append("scope=").append(URLEncoder.encode(SCOPE, "UTF-8"))
				.append("&");
		uriBuilder.append("redirect_uri=")
				.append(URLEncoder.encode(_redirectUri, "UTF-8")).append("&");
		uriBuilder.append("client_id=").append(_clientId).append("&");
		uriBuilder.append("accessType=").append(accessType);
		
		return uriBuilder.toString();
	}
	
	private void getProperties(String fileName) throws IOException {
		Properties prop = null;
		if (fileName == null) {
			prop = loadPropertiesAsResource();
		} else {
			prop = loadPropertiesAsResource(fileName);
		}
		_clientId = prop.getProperty("clientId");
	}
	
	private void init(String pfn) throws IOException {
		if (pfn != null) {
			getProperties(pfn);
		} else {
			getProperties(null);
		}

		// Google will call me back at the redirect URL. Set up a listener.
		_receiver = new LocalServerReceiver();
		_redirectUri = _receiver.getRedirectUri();
		System.out.println("Local receiver listening on port "
				+ _receiver.getPort());
		
		// Make sure to grant the token as an admin user. In my case,
		// ghays@accessreview.net.
		System.out.println("(1) Request authentication using OAuth 2.");
	}
	
	private void invokeBrowser(String url) throws IOException {
		if (Desktop.isDesktopSupported()) {
			Desktop deskTop = Desktop.getDesktop();
			if (deskTop.isSupported(Action.BROWSE)) {
				System.out.println("Attempting to browse to " + url + " ...");
				deskTop.browse(URI.create(url));
			}
		}
	}
	
	/**
	 * @see <a
	 *      href="http://stackoverflow.com/questions/333363/loading-a-properties-file-from-java-package">Loading
	 *      a properties file from Java package</a>
	 * @return
	 * @throws IOException
	 */
	private Properties loadPropertiesAsResource() throws IOException {
		Properties prop = new Properties();
		InputStream in = GoogleToken.class
				.getResourceAsStream("client.properties");
		prop.load(in);
		in.close();
		return prop;
	}
	
	private Properties loadPropertiesAsResource(String name) throws IOException {
		Properties prop = new Properties();
		InputStream in = GoogleToken.class
				.getResourceAsStream(name);
		prop.load(in);
		in.close();
		return prop;
	}
	
	/**
	 * Authenticate to Google Apps using OAuth 2.
	 * 
	 * @param args
	 * @throws IOException
	 */
	public static void main(String[] args) throws IOException {
		
		GoogleToken authCode = new GoogleToken();
		authCode.connect();
	}
	
	/**
	 * This is what the Google account chooser URI looks like.
	 * 
	 * <pre>
		https://accounts.google.com/AccountChooser?service=lso&continue=https%3A%2F%2Faccounts.google.com%2Fo
		%2Foauth2%2Fauth%3Fresponse_type%3Dcode%26scope%3Dhttps%3A%2F%2Fwww.googleapis.com%2Fauth
		%2Fadmin.directory.user%26redirect_uri%3Dhttp%3A%2F%2Flocalhost%3A14539%2FCallback%26client_id
		%3D430723156037-c3149idj1vhnqaotri5o5qem9prmm1hd.apps.googleusercontent.com%26accessType%3Doffline%26hl
		%3Den%26from_login%3D1%26as%3D-c695002fd5825cf&btmpl=authsub&hl=en
	 * </pre>
	 */
	
	/**
	 * <pre>
	 	2015-04-30 16:57:08.322:INFO::Logging to STDERR via org.mortbay.log.StdErrLog
		2015-04-30 16:57:08.323:INFO::jetty-6.1.26
		2015-04-30 16:57:08.346:INFO::Started SocketConnector@localhost:14975
		Local receiver listening on port 14975
		(1) Request authentication using OAuth 2.
		Making request to authorization URI: https://accounts.google.com/o/oauth2/auth?response_type=code&scope=https%3A%2F%2Fwww.googleapis.com%2Fauth%2Fadmin.directory.user&redirect_uri=http%3A%2F%2Flocalhost%3A14975%2FCallback&client_id=430723156037-c3149idj1vhnqaotri5o5qem9prmm1hd.apps.googleusercontent.com&accessType=offline
		Redirect URI: http://localhost:14975/Callback
		HTTP Response Status: 200
		Attempting to browse to https://accounts.google.com/AccountChooser?service=lso&continue=https%3A%2F%2Faccounts.google.com%2Fo%2Foauth2%2Fauth%3Fresponse_type%3Dcode%26scope%3Dhttps%253A%252F%252Fwww.googleapis.com%252Fauth%252Fadmin.directory.user%26redirect_uri%3Dhttp%253A%252F%252Flocalhost%253A14975%252FCallback%26client_id%3D430723156037-c3149idj1vhnqaotri5o5qem9prmm1hd.apps.googleusercontent.com%26accessType%3Doffline ...
		Waiting for the code...
		2015-04-30 16:57:15.034:INFO::Stopped SocketConnector@localhost:14975
		Google authorization code: 4/5BIHWBuGQWLoOjjcrSMR8L8GnySSea1q9QkNBHl0gUU.AkyzX7Xet3UaPm8kb2vw2M0D2qoYmgI
	 * </pre>
	 */
}