判断应用是否在后台

public static boolean isAppInBackgroundInternal(Context context) {
    ActivityManager manager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
    if (Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP) {
        List<ActivityManager.RunningAppProcessInfo> runningProcesses = manager.getRunningAppProcesses();
        if (!ListUtils.isEmpty(runningProcesses)) {
            for (ActivityManager.RunningAppProcessInfo runningProcess : runningProcesses) {
                if (runningProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
                    return false;
                }
            }
        }
    } else {
        List<ActivityManager.RunningTaskInfo> task = manager.getRunningTasks(1);
        if (!ListUtils.isEmpty(task)) {
            ComponentName info = task.get(0).topActivity;
            if (null != info) {
                return !isKaolaProcess(info.getPackageName());
            }
        }
    }
    return true;
}