Firebase Admin SDK for Android, methods not found

Question

I\'m building an Android app backed by a Firebase app, and I would like to be able to create an Admin account that can edit or delete other user accounts. If I\'m understand

Answer 1

As the accepted answer states, it's not a good idea to put Firebase Admin in your Android app that uses Firebase, because there are classes with the same names.

I wanted to create a custom token (https://firebase.google.com/docs/auth/android/custom-auth), so I ended up doing:

1) Create a separate UI-less server app.

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        finish()  // Just end the app here.
    }
}


    

2) Add an IntentService to the server app and generate a custom token.

class CustomTokenService : IntentService(CustomTokenService::class.java.simpleName) {
    // Runs in its own thread.
    override fun onHandleIntent(intent: Intent?) {    
        // Initialize FirebaseApp only when not already initialized.
        try {
            FirebaseApp.getInstance()
        } catch (ex: IllegalStateException) {
            try {
                val inputStream = assets.open("serviceAccountKey.json")
                val options = FirebaseOptions.Builder().
                        setCredential(FirebaseCredentials.fromCertificate(inputStream)).
                        setDatabaseUrl("https://YOUR_APP.firebaseio.com/").
                        build()
                FirebaseApp.initializeApp(options)
                inputStream.close()
            } catch (e: IOException) {
                e.printStackTrace()
            }
        }

        // In real life, you should verify ID/PW before creating custom token.
        val id = intent!!.getStringExtra("ID")
        val pw = intent.getStringExtra("PW")

        val additionalClaims = HashMap()
        additionalClaims.put("premiumAccount", true)

        FirebaseAuth.getInstance().createCustomToken(id, additionalClaims).
                addOnSuccessListener { customToken ->
            // Send custom token back to client.
            val resultReceiver = intent.getParcelableExtra(RESULT_RECEIVER)
            val bundle = Bundle()
            bundle.putString(CUSTOM_TOKEN, customToken)
            resultReceiver.send(Activity.RESULT_OK, bundle)
        }
    }
}

Note that I'm sending the custom token back to the client via "ResultReceiver", but you are free to use other ways, such as "Messenger" or "BroadcastReceiver".

3) From the client, I start the service that resides in the server app.

String MYSERVER = "SERVER_ID";  // e.g. "com.domain.myserver"
String CUSTOM_TOKEN_SERVICE = MYSERVER + ".CustomTokenService";

Intent intent = new Intent();
intent.putExtra("ID", ID);
intent.putExtra("PW", PW);
intent.putExtra(RESULT_RECEIVER, mResultReceiver);
intent.setComponent(new ComponentName(MYSERVER, CUSTOM_TOKEN_SERVICE));
getContext().startService(intent);

4) When I receive the custom token from the server app, I sign in to Firebase.

ResultReceiver resultReceiver = new ResultReceiver(new Handler()) {
    @Override
    protected void onReceiveResult(int resultCode, Bundle resultData) {
        String customToken = resultData.getString(CUSTOM_TOKEN);
        mFirebaseAuth.signInWithCustomToken(customToken);
    }
};
Parcel parcel = Parcel.obtain();
resultReceiver.writeToParcel(parcel, 0);
parcel.setDataPosition(0);
mResultReceiver = ResultReceiver.CREATOR.createFromParcel(parcel);
parcel.recycle();

5) And the Gradle config files.

buildscript {
    ext.kotlin_version = '1.2.21'
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.0.1'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        google()
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

---------------------------------------------------------------------------
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion 26

    defaultConfig {
        applicationId "org.solamour.myserver"
        minSdkVersion 14
        targetSdkVersion 26
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        multiDexEnabled true

        javaCompileOptions {
            annotationProcessorOptions {
                includeCompileClasspath false
            }
        }
        resConfigs "auto"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }

    // Conflict with dependency 'com.google.code.findbugs:jsr305' in project ':app'.
    // Resolved versions for app (1.3.9) and test app (2.0.1) differ.
    configurations.all {
        resolutionStrategy.force 'com.google.code.findbugs:jsr305:2.0.1'    // Or "1.3.9".
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
    implementation 'com.android.support:appcompat-v7:26.1.0'
    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.1'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'

    implementation 'com.google.firebase:firebase-admin:4.1.6'
    implementation 'com.android.support:multidex:1.0.2'
}

The highest Firebase Admin version I was able to use was "4.1.6"; anything after that involved a lot of modifications to the gradle file (and that didn't end up well either).