Android：flag_activity_reorder_to_front适用于startActivity但不适用于通知

Question

我想在点击通知时将活动A重新排序到前面，并且只有一个活动A的实例。

例如：
目前，我通过此订单启动了3项活动：Main-＆gt; A-＆gt; B

现在我点击通知并启动活动A，
我希望堆栈的顺序应该是：Main-＆gt; B-＆gt; A

但是，我得到的是：Main-＆gt; A-＆gt; B-＆gt; A

做这些事情的适当方法是什么？

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void onClick(View view) {
        Common.onClick(this, view);
    }
}

public class ActivityA extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void onClick(View view) {
        Common.onClick(this, view);
    }
}

public class ActivityB extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void onClick(View view) {
        Common.onClick(this, view);
    }
}

public class Common {

    public static void onClick(Activity activity, View view) {
        Intent intent;
        switch (view.getId()) {
            //new activity anyway
            case R.id.btnA:
                intent = new Intent(activity, ActivityA.class);
                activity.startActivity(intent);
                break;
            case R.id.btnB:
                intent = new Intent(activity, ActivityB.class);
                activity.startActivity(intent);
                break;
            //reorder activity to front
            case R.id.btnAF:
                intent = new Intent(activity, ActivityA.class);
                intent.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
                activity.startActivity(intent);
                break;
            case R.id.btnBF:
                intent = new Intent(activity, ActivityB.class);
                intent.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
                activity.startActivity(intent);
                break;
            //new activity anyway through notification
            case R.id.btnNA:
                intent = new Intent(activity, ActivityA.class);
                sendNotification(activity, intent, "New A", "New A");
                break;
            case R.id.btnNB:
                intent = new Intent(activity, ActivityB.class);
                sendNotification(activity, intent, "New B", "New B");
                break;
            //reorder activity to front through notification
            case R.id.btnNAF:
                intent = new Intent(activity, ActivityA.class);
                intent.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
                sendNotification(activity, intent, "A to Front", "A to Front");
                break;
            case R.id.btnNBF:
                intent = new Intent(activity, ActivityB.class);
                intent.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
                sendNotification(activity, intent, "B to Front", "B to Front");
                break;
        }
    }

    private static void sendNotification(Activity activity, Intent targetIntent, String title, String msg) {
        NotificationCompat.Builder mBuilder =
                new NotificationCompat.Builder(activity)
                        .setSmallIcon(R.drawable.abc_ic_menu_copy_mtrl_am_alpha)
                        .setContentTitle(title)
                        .setContentText(msg);

        TaskStackBuilder stackBuilder = TaskStackBuilder.create(activity);

        stackBuilder.addNextIntent(targetIntent);
        PendingIntent resultPendingIntent =
                stackBuilder.getPendingIntent(
                        0,
                        PendingIntent.FLAG_UPDATE_CURRENT
                );
        mBuilder.setContentIntent(resultPendingIntent);
        NotificationManager mNotificationManager =
                (NotificationManager) activity.getSystemService(Context.NOTIFICATION_SERVICE);

        mNotificationManager.notify(123456789, mBuilder.build());
    }
}


<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:orientation="vertical">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Activity" />

        <Button
            android:id="@+id/btnA"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:onClick="onClick"
            android:text="New A" />

        <Button
            android:id="@+id/btnB"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:onClick="onClick"
            android:text="New B" />

        <Button
            android:id="@+id/btnAF"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:onClick="onClick"
            android:text="A to Front" />

        <Button
            android:id="@+id/btnBF"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:onClick="onClick"
            android:text="B to Front" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:orientation="vertical">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Notification" />

        <Button
            android:id="@+id/btnNA"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:onClick="onClick"
            android:text="N New A" />

        <Button
            android:id="@+id/btnNB"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:onClick="onClick"
            android:text="N New B" />

        <Button
            android:id="@+id/btnNAF"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:onClick="onClick"
            android:text="N A to Front" />

        <Button
            android:id="@+id/btnNBF"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:onClick="onClick"
            android:text="N B to Front" />
    </LinearLayout>
</LinearLayout>