android 获取栈顶应用包名

可以使用以下代码获取当前栈顶应用的包名：

ActivityManager activityManager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
if (activityManager != null) {
    List<ActivityManager.RunningTaskInfo> runningTasks = activityManager.getRunningTasks(1);
    if (runningTasks != null && !runningTasks.isEmpty()) {
        ComponentName topActivity = runningTasks.get(0).topActivity;
        String packageName = topActivity.getPackageName();
        // packageName 就是当前栈顶应用的包名
    }
}

需要注意的是，该方法在 Android 5.0 及以上版本已经被废弃，推荐使用以下方法：

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
    UsageStatsManager usageStatsManager = (UsageStatsManager) getSystemService(Context.USAGE_STATS_SERVICE);
    if (usageStatsManager != null) {
        long endTime = System.currentTimeMillis();
        long beginTime = endTime - 10000; // 获取最近 10 秒内的应用使用情况
        UsageEvents.Event event = new UsageEvents.Event();
        UsageEvents usageEvents = usageStatsManager.queryEvents(beginTime, endTime);
        while (usageEvents.hasNextEvent()) {
            usageEvents.getNextEvent(event);
            if (event.getEventType() == UsageEvents.Event.MOVE_TO_FOREGROUND) {
                String packageName = event.getPackageName();
                // packageName 就是当前栈顶应用的包名
            }
        }
    }
}

需要注意的是，使用该方法需要添加权限：

<uses-permission android:name="android.permission.PACKAGE_USAGE_STATS" tools:ignore="ProtectedPermissions"/>