C# 反射修改私有靜態成員變量

//動態鏈接庫中PvsApiIfCtrl.Cls.Cls_Public類有一變量 private static string key="abcd";
//下面通過反射的技術修改和獲取值
//設置key 
public static void updatePalmKey(string key = "1234567890123456")
        {
            BindingFlags flag = BindingFlags.Static | BindingFlags.NonPublic;
            FieldInfo f_key = typeof(PvsApiIfCtrl.Cls.Cls_Public).GetField("key", flag);
            f_key.SetValue(new PvsApiIfCtrl.Cls.Cls_Public(), key);
        }

        /// <summary>
        /// 獲取key
        /// </summary>
        /// <returns></returns>
        public static string getPalmKey()
        {
            BindingFlags flag = BindingFlags.Static | BindingFlags.NonPublic;
            FieldInfo f_key = typeof(PvsApiIfCtrl.Cls.Cls_Public).GetField("key", flag);
            object o = f_key.GetValue(new PvsApiIfCtrl.Cls.Cls_Public());
            return o.ToString();
        }