1. Development of Twitter Applications Part 3. OAuth
Dr. Myungjin Lee

2. Twitter4J What is Twitter4J? Features API Support matrix
an unofficial Java library for the Twitter API
easily to integrate your Java application with the Twitter service
Features
100% Pure Java - works on any Java Platform version 5 or later
Android platform and Google App Engine ready
Zero dependency : No additional jars required
Built-in OAuth support
Out-of-the-box gzip support
100% Twitter API 1.1 compatible
API Support matrix

3. OAuth What is OAuth? Twitter’s OAuth
an open standard for authorization
a method for clients to access server resources on behalf of a resource owner
a process for end-users to authorize third-party access to their server resources without sharing their credentials
Twitter’s OAuth
OAuth v1.0a to provide authorized access to Twitter API
using HMAC-SHA1 signature

4. OAuth Process for Desktop Application

5. Registering Your Application
your application name
your application description
your application’s publicly accessible home page
webpage URL where twitter returns after successfully authenticating

6. Registering Your Application
Consumer Key and Secret to get user’s Access Token

7. Application type Read only Read and Write
Read Tweets from your timeline.
See who you follow.
Read and Write
See who you follow, and follow new people.
Update your profile.
Post Tweets for you.
Read, Write and Access direct messages
Access your direct messages.

8. Primary Classes and Interfaces of Twitter4J
TwitterFactory Class
A factory class for Twitter
Twitter Interface
basic interface to use all of APIs
AccessToken Class
Representing authorized Access Token which is passed to the service provider in order to access protected resources

9. Getting Access Token
// The factory instance is re-useable and thread safe.
Twitter twitter = TwitterFactory.getSingleton();
twitter.setOAuthConsumer("[consumer key]", "[consumer secret]");
RequestToken requestToken = null;
try {
requestToken = twitter.getOAuthRequestToken();
} catch (TwitterException e) {
// TODO Auto-generated catch block
e.printStackTrace(); }
AccessToken accessToken = null;
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
while (null == accessToken) {
System.out.println("Open the following URL and grant access to your account:");
System.out.println(requestToken.getAuthorizationURL());
System.out.print("Enter the PIN(if aviailable) or just hit enter.[PIN]:");
String pin = new String();
pin = br.readLine();
} catch (IOException e) {
if (pin.length() > 0) {
accessToken = twitter.getOAuthAccessToken(requestToken, pin);
} else {
accessToken = twitter.getOAuthAccessToken();
} catch (TwitterException te) {
if (401 == te.getStatusCode()) {
System.out.println("Unable to get the access token.");
te.printStackTrace();
// persist to the accessToken for future reference.
storeAccessToken(twitter.verifyCredentials().getId(), accessToken);

10. Getting Access Token
private static void storeAccessToken(long useId, AccessToken accessToken) {
// store accessToken.getToken() and accessToken.getTokenSecret()
System.out.println("User ID: " + useId);
System.out.println("Access Token: " + accessToken.getToken());
System.out.println("Access Token Secret: "
+ accessToken.getTokenSecret()); }
public static AccessToken loadAccessToken() {
String token = "[access token]";
String tokenSecret = "[access token secret]";
return new AccessToken(token, tokenSecret);

11. Test Code for Authentication
import twitter4j.IDs;
import twitter4j.Paging;
import twitter4j.Twitter;
import twitter4j.TwitterException;
import twitter4j.TwitterFactory;
import twitter4j.User;
import twitter4j.auth.AccessToken;
public class TwitterFriends {
public static void main(String args[]) {
Twitter twitter = TwitterFactory.getSingleton();
AccessToken accessToken = TwitterAccessToken.loadAccessToken();
twitter.setOAuthConsumer(TwitterAccessToken.consumerKey,
TwitterAccessToken.consumerSecret);
twitter.setOAuthAccessToken(accessToken);
IDs ids = null;
try {
ids = twitter.getFollowersIDs(-1);
} catch (TwitterException e) {
// TODO Auto-generated catch block
e.printStackTrace(); }
long[] idArray = ids.getIDs();
for (int i = 0; i < idArray.length; i++) {
User u = null;
u = twitter.showUser(idArray[i]);
System.out.println("Name: " + u.getName());

12. References http://en.wikipedia.org/wiki/Oauth