Last updated on: March 4, 2020
Today, I’ll show you how to implement the ‘Log in with GitHub’ button into your Android app.
We’re going to use 3-legged Authorization(OAuth) to get the authorization code and exchange it later for the access token. Using the access token, we’ll be able to get user’s information and email address making an HTTP request to https://api.github.com/user
Contents
Let’s get started!
First, we need to create the Client ID and Client Secret on the GitHub website.
Go to https://github.com/settings/developers and press the Register a new application button.
Fill the required fields and press Register application.
On the new page, you’ll see the Client ID and Client Secret we going to use later.
Adding the dependencies
In this tutorial, we’re going to use Coroutines, which will help us do HTTP POST requests easier.
In the build.gradle file of your app add the following dependency:
dependencies {
// ...
implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.3.5'
// ...
}Code language: Kotlin (kotlin)Creating the GitHub Login Button
First, add a Button to your XML file. In this example, we have a button in the middle of the activity_main.xml.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/colorPrimary"
tools:context=".MainActivity">
<Button
android:id="@+id/github_login_btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:background="@drawable/rounded_corners"
android:drawablePadding="8dp"
android:drawableStart="@drawable/github_icon"
android:drawableLeft="@drawable/github_icon"
android:padding="8dp"
android:text="Log in with GitHub"
android:textAllCaps="false"
android:textColor="@android:color/white" />
</RelativeLayout>Code language: HTML, XML (xml)
Create a new Kotlin object file by right-clicking on your app’s package name on the left side and go New > Kotlin File/Class.
Give it the name GithubConstants, choose Object and press OK.
Inside the new file, copy and paste the following code and replace the CLIENT_ID, CLIENT_SECRET and REDIRECT_URI with yours.
object GithubConstants {
val CLIENT_ID = "MY_CLIENT_ID"
val CLIENT_SECRET = "MY_CLIENT_SECRET"
val REDIRECT_URI = "MY_REDIRECT_URI"
val SCOPE = "read:user,user:email"
val AUTHURL = "https://github.com/login/oauth/authorize"
val TOKENURL = "https://github.com/login/oauth/access_token"
}Code language: Kotlin (kotlin)In your AndroidManifest.xml file, add internet permission.
<uses-permission android:name="android.permission.INTERNET" />Code language: HTML, XML (xml)In the Kotlin class of your Activity (In this example is the MainActivity), add a listener to your button, and create a Dialog with a WebView inside.
lateinit var githubAuthURLFull: String
lateinit var githubdialog: Dialog
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val state = TimeUnit.MILLISECONDS.toSeconds(System.currentTimeMillis())
githubAuthURLFull =
GithubConstants.AUTHURL + "?client_id=" + GithubConstants.CLIENT_ID + "&scope=" + GithubConstants.SCOPE + "&redirect_uri=" + GithubConstants.REDIRECT_URI + "&state=" + state
github_login_btn.setOnClickListener {
setupGithubWebviewDialog(githubAuthURLFull)
}
}
// Show Github login page in a dialog
@SuppressLint("SetJavaScriptEnabled")
fun setupGithubWebviewDialog(url: String) {
githubdialog = Dialog(this)
val webView = WebView(this)
webView.isVerticalScrollBarEnabled = false
webView.isHorizontalScrollBarEnabled = false
webView.webViewClient = GithubWebViewClient()
webView.settings.javaScriptEnabled = true
webView.loadUrl(url)
githubdialog.setContentView(webView)
githubdialog.show()
}Code language: Kotlin (kotlin)This WebView uses a custom WebViewClient, named GithubWebViewClient.
This helps to ‘catch’ the URL with the authorization code after the user has given access to your app.
// A client to know about WebView navigations
// For API 21 and above
@Suppress("OverridingDeprecatedMember")
inner class GithubWebViewClient : WebViewClient() {
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
override fun shouldOverrideUrlLoading(
view: WebView?,
request: WebResourceRequest?
): Boolean {
if (request!!.url.toString().startsWith(GithubConstants.REDIRECT_URI)) {
handleUrl(request.url.toString())
// Close the dialog after getting the authorization code
if (request.url.toString().contains("code=")) {
githubdialog.dismiss()
}
return true
}
return false
}
// For API 19 and below
override fun shouldOverrideUrlLoading(view: WebView, url: String): Boolean {
if (url.startsWith(GithubConstants.REDIRECT_URI)) {
handleUrl(url)
// Close the dialog after getting the authorization code
if (url.contains("?code=")) {
githubdialog.dismiss()
}
return true
}
return false
}
// Check webview url for access token code or error
private fun handleUrl(url: String) {
val uri = Uri.parse(url)
if (url.contains("code")) {
val githubCode = uri.getQueryParameter("code") ?: ""
requestForAccessToken(githubCode)
}
}
}Code language: Kotlin (kotlin)After getting the authorization code, you need to exchange it for an access token by making an HTTP POST request to https://github.com/login/oauth/access_token
fun requestForAccessToken(code: String) {
val grantType = "authorization_code"
val postParams =
"grant_type=" + grantType + "&code=" + code + "&redirect_uri=" + GithubConstants.REDIRECT_URI + "&client_id=" + GithubConstants.CLIENT_ID + "&client_secret=" + GithubConstants.CLIENT_SECRET
GlobalScope.launch(Dispatchers.Default) {
val url = URL(GithubConstants.TOKENURL)
val httpsURLConnection =
withContext(Dispatchers.IO) { url.openConnection() as HttpsURLConnection }
httpsURLConnection.requestMethod = "POST"
httpsURLConnection.setRequestProperty(
"Accept",
"application/json"
);
httpsURLConnection.doInput = true
httpsURLConnection.doOutput = true
val outputStreamWriter = OutputStreamWriter(httpsURLConnection.outputStream)
withContext(Dispatchers.IO) {
outputStreamWriter.write(postParams)
outputStreamWriter.flush()
}
val response = httpsURLConnection.inputStream.bufferedReader()
.use { it.readText() } // defaults to UTF-8
withContext(Dispatchers.Main) {
val jsonObject = JSONTokener(response).nextValue() as JSONObject
val accessToken = jsonObject.getString("access_token") //The access token
// Get user's id, first name, last name, profile pic url
fetchGithubUserProfile(accessToken)
}
}
}Code language: Kotlin (kotlin)After having the access token, you can get user’s Id, Display Name, Profile pic URL and email address with an HTTP GET request.
fun fetchGithubUserProfile(token: String) {
GlobalScope.launch(Dispatchers.Default) {
val tokenURLFull =
"https://api.github.com/user"
val url = URL(tokenURLFull)
val httpsURLConnection =
withContext(Dispatchers.IO) { url.openConnection() as HttpsURLConnection }
httpsURLConnection.requestMethod = "GET"
httpsURLConnection.setRequestProperty("Authorization", "Bearer $token")
httpsURLConnection.doInput = true
httpsURLConnection.doOutput = false
val response = httpsURLConnection.inputStream.bufferedReader()
.use { it.readText() } // defaults to UTF-8
val jsonObject = JSONTokener(response).nextValue() as JSONObject
Log.i("GitHub Access Token: ", token)
// GitHub Id
val githubId = jsonObject.getInt("id")
Log.i("GitHub Id: ", githubId.toString())
// GitHub Display Name
val githubDisplayName = jsonObject.getString("login")
Log.i("GitHub Display Name: ", githubDisplayName)
// GitHub Email
val githubEmail = jsonObject.getString("email")
Log.i("GitHub Email: ", githubEmail)
// GitHub Profile Avatar URL
val githubAvatarURL = jsonObject.getString("avatar_url")
Log.i("Github Profile Avatar URL: ", githubAvatarURL)
}
}Code language: Kotlin (kotlin)Done!
You can find the final project here
If you have any questions, please feel free to leave a comment below