Chrome Custom Tabs redirect to Android app will close the app

Question

I am trying to implement an OAuth2 flow with an Android Chrome Custom Tab but my app is always closed (no crash) when the Chrome Custom Tab is receiving the 302 with the location/scheme of my app.

If I create a HTML page with ahref link and touch manually on it the Chrome Custom Tab is correctly switching to my app.

Seems like when handling the server 302 redirect in the Chrome Custom Tab it will not correctly handle my custom app scheme... but why?

If I try the same redirect URL in a stock browser or with a WebView everything is working too.

Here is my current setup:

MainActiviy.java

    Button btnChromeCustomTab = (Button) findViewById(R.id.btnChromeCustomTab);
    btnChromeCustomTab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            CustomTabsIntent customTabsIntent = new CustomTabsIntent.Builder().build();
            String packageName = CustomTabsHelper.getPackageNameToUse(MainActivity.this);
            customTabsIntent.intent.setPackage(packageName);
            Uri theLocationUri = Uri.parse(URL);
            customTabsIntent.launchUrl(MainActivity.this, theLocationUri);
        }
    });

AndroidManifest.xml

    <activity android:name=".MainActivity" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>

        <intent-filter android:label="@string/filter_title">
            <action android:name="android.intent.action.VIEW" />
            <category android:name="android.intent.category.DEFAULT" />
            <category android:name="android.intent.category.BROWSABLE" />
            <data android:scheme="myappscheme" android:host="oauth" />
        </intent-filter>
    </activity>

This is the redirect URL that the app received with HTTP 302 code:

myappscheme://oauth?code=1234567&state=tokenCheck123

build.gradle

android {
compileSdkVersion 23
buildToolsVersion "23.0.2"

defaultConfig {
    applicationId "de.myapptest.webviewtest"
    minSdkVersion 16
    targetSdkVersion 23
    versionCode 1
    versionName "1.0"
}

dependencies {
   compile fileTree(dir: 'libs', include: ['*.jar'])
   testCompile 'junit:junit:4.12'
   compile 'com.android.support:appcompat-v7:23.2.1'
   compile 'com.android.support:design:23.2.1'
   compile 'com.android.support:customtabs:23.0.0+'
}

Thanks for any help...

Answer 1

I've also observed my Android app unexpectedly background after server-side 302 redirection to a custom scheme, and observed expected handling from stand-alone Chrome and manually triggered redirection in the client.

I was able to "fix" the issue by calling the warmup function before loading the url that redirects.

In other words, this works:

void launchTab(Context context, Uri uri){
    final CustomTabsServiceConnection connection = new CustomTabsServiceConnection() {
        @Override
        public void onCustomTabsServiceConnected(ComponentName componentName, CustomTabsClient client) {
            final CustomTabsIntent.Builder builder = new CustomTabsIntent.Builder();
            final CustomTabsIntent intent = builder.build();
            client.warmup(0L); // This prevents backgrounding after redirection
            intent.launchUrl(context, uri);
        }
        @Override
        public void onServiceDisconnected(ComponentName name) {}
    };
    CustomTabsClient.bindCustomTabsService(context, "com.android.chrome", connection);
}

This doesn't work:

void launchTab(Context context, Uri uri){
    final CustomTabsIntent.Builder builder = new CustomTabsIntent.Builder();
    final CustomTabsIntent intent = builder.build();
    intent.launchUrl(context, uri);
}

The Chrome Custom Tab docs describe warming up as a best practice, but it also appears to help ensure expected behavior.

In terms of env, I'm testing on a Nexus 5X w Chrome 51. My chrome tab dependency in Gradle looks like this:

dependencies {
    compile 'com.android.support:customtabs:24.0.0'

Answer 2

If I used android:launchMode="singleInstance" there were multiple instances in the task manager so this was no option.

Starting the CustomTabsIntent with FLAG_ACTIVITY_NEW_TASK Flag did the trick.

CustomTabsIntent.Builder builder = new CustomTabsIntent.Builder();
CustomTabsIntent intent = builder.build();

intent.intent.setFlags(FLAG_ACTIVITY_NEW_TASK);
intent.launchUrl(context, Uri.parse(url));