Viewing Github profile using OAuth in Java

Hello everyone! I have discussed the basics of OAuth and its components in the previous post. Let's see how to develop a simple java application to view your Github profile details using OAuth. We need to have a Github account in order to build this application. 

Connect your application to Github

• Add a new application

In your Github account, go to settings and select Developer settings. Click on New OAuth app.

• Register your new application

Provide your application name, homepage URL and callback URL in the relevant fields and click Register application.

• Get your Client ID and Client Secret key

Copy your Client ID and Client Secret and select update application

Build the application

Now, let's build the Java application. The main flow is as follows

1. User will click on Auth login link
2. Github Auth server will show permission screen to the user
3. Once the user accepts to the scope, it will send the code to App Server ( Redirect URI)
4. Once we got the code, we can get access token by using client secret id
5. We can access user's information using that access token 

Construct the login URL

In order to get the user's Github profile details, we need to create a URL for the user to login with Github. The following parameters should be included

• client_id      - the client id obtained from Github
• redirect_uri - the URL to where the user should be redirected
• scope       -  type of information that you need. We have given as user here since we need profile info(More available scopes )

The sample URL is as follows

https://github.com/login/oauth/authorize?client_id=5338aaaaaaa812789cf8&redirect_uri=http://abc.com/oauth&scope=user

Get Access Token

Once the user has authenticated and provided the permission, the app will be redirected to the given redirect_uri. Now, we can access the "code" from Java and create another URL to get the access token. We need to provide the client_id, redirect_uri,client_secret and the code that we obtained.

String code = request.getParameter("code");
URL url = new URL("https://github.com/login/oauth/access_token?client_id="+clientID + "&redirect_uri="+ redirectURI+ "&client_secret=" + clientSecret + "&code=" + code);

After posting this URL, we will get the access token. 

Get user details from the access token

After retrieving the access token, we can make a GET request to access the user details.

https://api.github.com/user

The response to the request will be like this.

{
  "login": "octocat",
  "id": 1,
  "node_id": "MDQ6VXNlcjE=",
  "avatar_url": "https://github.com/images/error/octocat_happy.gif",
  "gravatar_id": "",
  "url": "https://api.github.com/users/octocat",
  "html_url": "https://github.com/octocat",
  "followers_url": "https://api.github.com/users/octocat/followers",
  "following_url": "https://api.github.com/users/octocat/following{/other_user}",
  "gists_url": "https://api.github.com/users/octocat/gists{/gist_id}",
  "starred_url": "https://api.github.com/users/octocat/starred{/owner}{/repo}",
  "subscriptions_url": "https://api.github.com/users/octocat/subscriptions",
  "organizations_url": "https://api.github.com/users/octocat/orgs",
  "repos_url": "https://api.github.com/users/octocat/repos",
  "events_url": "https://api.github.com/users/octocat/events{/privacy}",
  "received_events_url": "https://api.github.com/users/octocat/received_events",
  "type": "User",
  "site_admin": false,
  "name": "monalisa octocat",
  "company": "GitHub",
  "blog": "https://github.com/blog",
  "location": "San Francisco",
  "email": "octocat@github.com",
  "hireable": false,
  "bio": "There once was...",
  "public_repos": 2,
  "public_gists": 1,
  "followers": 20,
  "following": 0,
  "created_at": "2008-01-14T04:33:35Z",
  "updated_at": "2008-01-14T04:33:35Z",
  "total_private_repos": 100,
  "owned_private_repos": 100,
  "private_gists": 81,
  "disk_usage": 10000,
  "collaborators": 8,
  "two_factor_authentication": true,
  "plan": {
    "name": "Medium",
    "space": 400,
    "private_repos": 20,
    "collaborators": 0
  }
}

From the above response, the user profile will be created.