#region 更新赋值,前者赋值给后者
        public static void ShadowCopy(object a, object b)
        {
            if (a == null) return;

            if (a.GetType() == b.GetType())
            {
                PropertyInfo[] properties = a.GetType().GetProperties();

                foreach (var p in properties)
                {
                    var value = http://www.mamicode.com/p.GetValue(a, null);
                    if (value != GetDefault(p.GetType()))
                        p.SetValue(b, value, null);
                }
            }
        }

        public static object GetDefault(Type type)
        {
            if (type.IsValueType)
            {
                return Activator.CreateInstance(type);
            }
            return null;
        }

        #endregion