判断某个Activity是否在前台

 
    public fun isForeground(context: Context?, className: String):Boolean {
        if (context == null || TextUtils.isEmpty(className)) return false
        val am = context.getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
        val list = am.getRunningTasks(10)
        if (list != null && list.size > 0) {
            val cpn = list[0].topActivity
            if (className == cpn.className) return true
        }
        return false
    }