public class ActivityForeground {


    /**
     * 判斷某個界面是否在前臺
     *
     * @param activity 要判斷的Activity
     * @return 是否在前臺顯示
     */
    public static boolean isForeground(Activity activity) {
        return isForeground(activity, activity.getClass().getName());
    }

    /**
     * 判斷某個界面是否在前臺
     *
     * @param context   Context
     * @param className 界面的類名
     * @return 是否在前臺顯示
     */
    public static boolean isForeground(Context context, String className) {
        if (context == null || TextUtils.isEmpty(className))
            return false;
        ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
        List<ActivityManager.RunningTaskInfo> list = am.getRunningTasks(1);
        if (list != null && list.size() > 0) {
            ComponentName cpn = list.get(0).topActivity;
            if (className.equals(cpn.getClassName()))
                return true;
        }
        return false;
    }

}

通過ActivityManager獲取所有正在運行的activity列表集合,遍歷集合,查看對應(yīng)第一個元素的類名是否和要判斷的activity的名稱一樣