将对象内的属性以及属性值输出

public static string ToProperties_V(this object obj)        {            if (obj == null) return "";            var s = obj.GetType();             StringBuilder app = new StringBuilder();            foreach (var item in s.GetProperties())            {                app.Append($"{item.Name}:{item.GetValue(obj)}\n");             }            return app.ToString().Trim(',');        }