When implementing a custom account type in AccountManager
in Android I have the following problem for the sign in flow:
The sign in should happen through an OAuth provider. Therefore I have created a SignInActivity
which launches a WebView
and starts an OAuth flow. This works fine, when the callback is received to my-custom-scheme://callback
the WebView
detects it, receives the code
querystring parameter and completes the flow. The disadvantage with using a WebView
is that even though the user might already have an active session in the browser, this session is not used in the WebView
so the user will have to login again in the WebView
.
To solve this, I tried switching to using an intent-filter
in AndroidManifest.xml
, like this:
<intent-filter>
<action android:name="android.intent.action.VIEW" />
<category android:name="android.intent.category.DEFAULT" />
<category android:name="android.intent.category.BROWSABLE" />
<data android:scheme="my-custom-scheme" android:path="callback"/>
</intent-filter>
Instead of opening a WebView
in the SignInActivity
, I then launch a browser intent and wait for the browser to hit my-custom-scheme://callback
.
Intent browserIntent = new Intent(Intent.ACTION_VIEW, "http://oauth2provider/authorize");
startActivity(browserIntent);
finish();
In my SignInActivity
I have the following code to handle the callback:
if (intent != null && intent.getData() != null && getString("my-custom-scheme").equals(intent.getData().getScheme())) {
String code = getIntent().getData().getQueryParameter("code");
// complete oauth flow
}
This works. But, to the problem (finally!):
SignInActivity
will launch to handle the intent. As this activity is invisible, the browser will stay open on the sign in page, and to the user it will look like nothing happened. The browser never closes.So my question is: is there anyway to make the browser behave differently after having redirected to my-custom-scheme://callback? Ideally, I would like it to simply close after having redirected to the callback, and to return to the previous activity in the activity stack (i.e. to the activity that started the SignInActivity
from the beginning).
A task is a collection of activities that users interact with when trying to do something in your app. These activities are arranged in a stack—the back stack—in the order in which each activity is opened. For example, an email app might have one activity to show a list of new messages.
When using this flag, if a task is already running for the activity you are now starting, then a new activity will not be started; instead, the current task will simply be brought to the front of the screen with the state it was last in. See FLAG_ACTIVITY_MULTIPLE_TASK for a flag to disable this behavior.
An Intent is a messaging object you can use to request an action from another app component. Although intents facilitate communication between components in several ways, there are three fundamental use cases: Starting an activity. An Activity represents a single screen in an app.
Task affinity lets you define which task an activity belongs to. By default, an activity has the same task affinity as its root activity. With task affinity, we can now separate activities into different tasks. <activity android:name=".Activity_A"
I used the next approach to fix the same issue.
Let's assume we have MainActivity
with Sign In
button. Instead of starting browser directly clicking on that button I'm starting SignInActivity
using startActivityForResult
method. It's using for then I can handle result of login flow.
startActivityForResult(new Intent(this, SignInActivity.class), requestCode);
SignInActivity
is responsible for:
custom-scheme://callback
MainActivity
So, its onCreate
method looks like:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.login);
if (intent != null && intent.getData() != null && "custom-scheme".equals(intent.getData().getScheme())) {
String code = getIntent().getData().getQueryParameter("code");
// complete oauth flow
} else {
Intent browserIntent = new Intent(Intent.ACTION_VIEW, "http://oauth2provider/authorize")
.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP | Intent.FLAG_ACTIVITY_NO_HISTORY | Intent.FLAG_FROM_BACKGROUND);
startActivity(browserIntent);
finish();
}
}
Admit flags set into the browser intent.
This way if SignInActivity
is opened from MainActivity
it just opens login page in the browser and if it's opened catching redirect url it completes login flow sending appropriate request.
After you complete login flow sending the code to some endpoint in your callback method you should do the following:
setResult(Activity.RESULT_OK);
this.finish();
Naturally, you receive access_token from that endpoint. You can store it somewhere either here, in the success callback or return it back to the MainActivity
to handle it there.
As layout for SignInActivity
you can use just ProgressBar
in the center of the page. It will appear during login flow completion after SignInActivity
is opened caught redirect url (custom-scheme://callback
).
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<ProgressBar
android:layout_width="48dp"
android:layout_height="48dp"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true"
/>
</RelativeLayout>
Here is declaration of SignInActivity
in AndroidManifest.xml
<activity android:name=".SignInActivity"
android:launchMode="singleTask"
android:noHistory="true"
>
<intent-filter>
<action android:name="android.intent.action.VIEW" />
<category android:name="android.intent.category.DEFAULT"/>
<category android:name="android.intent.category.BROWSABLE"/>
<data android:scheme="custom-scheme" android:host="callback"/>
</intent-filter>
</activity>
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