从一个整数：

YourEnum foo = (YourEnum)yourInt;

从一个字符串：

YourEnum foo = (YourEnum) Enum.Parse(typeof(YourEnum), yourString);

// The foo.ToString().Contains(",") check is necessary for enumerations marked with an [Flags] attribute
if (!Enum.IsDefined(typeof(YourEnum), foo) && !foo.ToString().Contains(","))
{
    throw new InvalidOperationException($"{yourString} is not an underlying value of the YourEnum enumeration.")
}

更新：

从号码你也可以

YourEnum foo = (YourEnum)Enum.ToObject(typeof(YourEnum) , yourInt);