调用onCreate（）而不是onActivityResult（）

Question

So I am authenticating the user via GitHub account using OAuth from browser. But after I fire the Intent from LoginActivity , the onResume() gets executed before the user opens the browser, thus returning the value of uri equals null .

Here is the LoginActivity :

public class LoginActivity extends AppCompatActivity {

    Button loginButton;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        loginButton = findViewById(R.id.button);
        final String url = "oauth url...";
        Log.d("called","oncreate");
        loginButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.d("called","onclick");
                attemptLogin(url);
            }
        });
    }

    private void attemptLogin(String url){
        Log.d("called","onattempt");
        Intent intent = new Intent(this, BrowserActivity.class);
        intent.putExtra("URL", url);
        startActivityForResult(intent, 1);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        Uri uri = data.getData();
        String code = uri.getQueryParameter("code");
        Log.d("called",code);
    }
}

BrowserActivity :

public class BrowserActivity extends AppCompatActivity {

    public static String CALLBACK_URL = "callback url..";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_browser);
        Intent intent = getIntent();
        if(intent != null){
            String url = intent.getStringExtra("URL");
            Intent i = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
            startActivity(i);
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        Uri uri = getIntent().getData();
        if(uri != null && uri.toString().startsWith(CALLBACK_URL)) {
            String code = uri.getQueryParameter("code");
            Intent intent = new Intent();
            intent.putExtra("code",code);
            setResult(RESULT_OK, intent);
            finish();
        }
    }
}

LoginActivity in AndroidManifest.xml :

<activity
    android:name=".ui.activities.LoginActivity"
    android:label="@string/app_name"
    android:theme="@style/AppTheme.NoActionBar">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>
<activity android:name=".ui.activities.BrowserActivity"
          android:label="@string/app_name"
          android:theme="@style/AppTheme.NoActionBar">
    <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:host="callback"
            android:scheme="app"
            />
    </intent-filter>
</activity>

Answer 1

First, you start the browser with

Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
    startActivityForResult(intent, 1);

this intent does not return any result. It only request the browser to show the url. So the browser does not returning any result. However, after authentification, the browser trigger an intent and request for a new instance of LoginActivity. onCreate() is called of course

It is like LoginActivity(#1) -> Browser -> LoginActivity(#2)

you can call this portion of code inside onCreate() it will work:

Uri uri = getIntent().getData();
String code = uri.getQueryParameter("code");
Log.d("called",code);

But two different intents(launcher and action_view) can reach the same activity for two different purposes. You'd better create two different activities. First your usual LoginActivity and a second one (which inherit from the first) BrowserActivity wich redifine onCreate. So far, your Manifest will look like

<activity
android:name=".ui.activities.LoginActivity"
android:label="@string/app_name"
android:theme="@style/AppTheme.NoActionBar">
<intent-filter>
    <action android:name="android.intent.action.MAIN" />
    <category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".ui.activities.BrowserActivity"
android:label="@string/app_name"
android:theme="@style/AppTheme.NoActionBar">

<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:host="callback"
        android:scheme="app"
        />
</intent-filter>
</activity>

The LoginActivity code should look like this:

public class LoginActivity extends AppCompatActivity {

Button loginButton;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);
    loginButton = findViewById(R.id.button);
    final String url = "oauth url...";
    Log.d("called","oncreate");
    loginButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Log.d("called","onclick");
            attemptLogin(url);
        }
    });
}

private void attemptLogin(String url){
    Log.d("called","onattempt");

        // open the browser with url

        Intent i = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
        startActivity(i);
}

// no onResult 

}

And this is the BrowserActivityCode:

public class BrowserActivity extends LoginActivity {

// this will be triggered after authentification
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    processIntent();
}


protected void processIntent() {
    Intent intentFromBrowser = getIntent();
    if (intentFromBrowser != null) {
        Uri uri = intentFromBrowser.getData();
    if(uri != null && uri.toString().startsWith(CALLBACK_URL)) {
        String code = uri.getQueryParameter("code");
        Log.d("code value", code);
    }
    }
}
}