I'm working on an Android application that includes communication with the Amazon S3 servers. The app is being developed in Unity and I would like to include a system so that the users can authenticate with their Google Accounts and then use those credentials to access the S3 server through Cognito. To do that, I need to implement a Google Authenticator system in Unity, and I am having a hard time figuring out how to do it. My current approach consists in creating a Plugin with Android Studio to access the Google Sign In API, but every time I execute the program, it throws a NoClassDefFoundError exception. Here is my logcat:
03-25 20:45:34.968 25581-25610/? D/MainActivity: Authenticating... 03-25 20:45:35.086 25581-25610/? I/Unity: AndroidJavaException: java.lang.NoClassDefFoundError: Failed resolution of: Lcom/google/android/gms/auth/api/signin/GoogleSignInOptions$Builder; java.lang.NoClassDefFoundError: Failed resolution of: Lcom/google/android/gms/auth/api/signin/GoogleSignInOptions$Builder; at com.unityplugin.MainActivity.authenticate(MainActivity.java:55) at com.unity3d.player.UnityPlayer.nativeRender(Native Method) at com.unity3d.player.UnityPlayer.a(Unknown Source) at com.unity3d.player.UnityPlayer$b.run(Unknown Source) Caused by: java.lang.ClassNotFoundException: Didn't find class "com.google.android.gms.auth.api.signin.GoogleSignInOptions$Builder" on path: DexPathList[[zip file "/data/app/com.unityplugin-2/base.apk"],nativeLibraryDirectories=[/data/app/com.unityplugin-2/lib/arm, /data/app/com.unityplugin-2/base.apk!/lib/armeabi-v7a, /vendor/lib, /system/lib]] at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56) at java.lang.ClassLoader.loadClass(ClassLoader.java:511) at java.lang.ClassLoader.loadCla Here is the relevant part of my Android code (UnityPlayer Activity):
public void authenticate() { Log.d(TAG, "Authenticating..."); // Configure sign-in to request the user's ID, email address, and basic // profile. ID and basic profile are included in DEFAULT_SIGN_IN. //HERE IS THE ERROR (LINE 55) GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN) .requestIdToken(Constants.GOOGLE_CLIENT_ID) .requestEmail() .build(); // Build a GoogleApiClient with access to the Google Sign-In API and the // options specified by gso. mGoogleApiClient = new GoogleApiClient.Builder(this) .addApi(Auth.GOOGLE_SIGN_IN_API, gso) .addConnectionCallbacks(new ConnCallBack()) .addOnConnectionFailedListener(new FailedListener()) .build(); Intent signInIntent = Auth.GoogleSignInApi.getSignInIntent(mGoogleApiClient); startActivityForResult(signInIntent, RC_SIGN_IN); } The code works if I execute it in a native APK inside a Compact Activity, but when I make it into a plugin and run it with Unity, I get the error. In Unity, I call the authenticate() method with this code:
//Get Activity AndroidJavaClass unity = new AndroidJavaClass("com.unity3d.player.UnityPlayer"); AndroidJavaObject currentActivity = unity.GetStatic<AndroidJavaObject>("currentActivity"); //Call function authenticate currentActivity.Call("authenticate"); I have tried including the classes.jar file in the com.google.android.gms.play-services-auth-8.4.0 external library that I have in Android Studio, but it didn't work. I have also considered implementing the authentication directly in Unity instead of making a plugin, but all the information that I saw about doing something like that relates to Google Play Games, and I am not interested in including the Google Play Games API in my application, I just want to let the users log in with their Google account so that they can access the S3 server. If anyone has implemented a similar feature with Unity and knows a better way of doing this, I'm all ears. I am open to using a different way to enable Google Authentication in my app, the only requisite is that it has to be done in Unity.
Thanks in advance!