关于.Net类型转换

        public static T ChangeType<T>(object value)
        {
            Type conversionType = typeof(T);
            if (value is DBNull)
            {
                return default(T);
            }
            if (conversionType.IsGenericType && conversionType.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))
            {
                if (value == null) { return default(T); }
                conversionType = Nullable.GetUnderlyingType(conversionType); ;
            }
            return (T)Convert.ChangeType(value, conversionType);
        }