asp.net如何创建字母和数字验证码

pageload（object sender, eventarges e）{ string chkCode = string.Empty; //颜色列表，用于验证码、噪线、噪点 Color[] color = { Color.Black, Color.Red, Color.Blue, Color.Green, Color.Orange, Color.Brown, Color.Brown, Color.DarkBlue }; //字