求一个验证码的代码。
从别人的那里拿了一个，但是背景颜色太深，看起来不舒服，我也改不好那个背景色，就向大家求一个
最好带上代码和前台调用的方法。


[解决办法]
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Text;



protected void Page_Load(object sender, EventArgs e)
{
string chkCode = string.Empty;
//颜色列表，用于验证码、噪线、噪点
Color[] color = { Color.Black, Color.Blue, Color.Green, Color.Orange, Color.Brown, Color.DarkBlue, Color.Red, Color.Purple, Color.Chocolate };
//字体列表，用于验证码
string[] font = { "Times New Roman", "MS Mincho", "Book Antiqua", "Gungsuh", "PMingLiU", "Impact", "Arial" };
char[] character = { '2', '3', '4', '5', '6', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'R', 'S', 'T', 'W', 'X', 'Y', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'k', 'm', 'n', 'p', 'r', 's', 't', 'w', 'x', 'y' };
Random rnd = new Random();
//给验证码随机3个西文字符
for (int i = 0; i < 3; i++)
{
chkCode += character[rnd.Next(character.Length)];
}
//再随机加一个中文字符
chkCode+=GeberateChineseCheckCode(1);
//保存验证码的Cookie
HttpCookie anycookie = new HttpCookie("validateCookie");
anycookie.Values.Add("ChkCode", chkCode);
HttpContext.Current.Response.Cookies["validateCookie"].Values["ChkCode"] = chkCode;
Bitmap bmp = new Bitmap(90, 30);
Graphics g = Graphics.FromImage(bmp);
g.Clear(Color.White);
//画噪线
//for (int i = 0; i < 2; i++)
//{
// int x1 = rnd.Next(90);
// int y1 = rnd.Next(30);
// int x2 = rnd.Next(90);
// int y2 = rnd.Next(30);
// Color clr = color[rnd.Next(color.Length)];
// g.DrawLine(new Pen(clr), x1, y1, x2, y2);
//}
//画验证码字符串
for (int i = 0; i < chkCode.Length; i++)
{
string fnt = font[rnd.Next(font.Length)];
Font ft = new Font(fnt, 14);
Color clr = color[rnd.Next(color.Length)];
g.DrawString(chkCode[i].ToString(), ft, new SolidBrush(clr), (float)i * 20 , (float)3);
}
//画噪点
for (int i = 0; i < 150; i++)
{
int x = rnd.Next(bmp.Width);
int y = rnd.Next(bmp.Height);
Color clr = color[rnd.Next(color.Length)];
bmp.SetPixel(x, y, clr);
}
//清除该页输出缓存，设置该页无缓存
Response.Buffer = true;
Response.ExpiresAbsolute = System.DateTime.Now.AddMilliseconds(0);
Response.Expires = 0;
Response.CacheControl = "no-cache";
Response.AppendHeader("Pragma", "No-Cache");
//将验证码图片写入内存流，并将其以"image/Png" 格式输出
MemoryStream ms = new MemoryStream();
try
{
bmp.Save(ms, ImageFormat.Png);
Response.ClearContent();
Response.ContentType = "image/Png";
Response.BinaryWrite(ms.ToArray());
}
finally
{
//显式释放资源
bmp.Dispose();
g.Dispose();
}
}

/// <summary>
/// 产生随机验证码，可选用
/// </summary>
/// <returns></returns>
string GenerateCheckCode()
{
int number;
string randomCode = string.Empty;
Random r = new Random();
for (int i = 0; i < 5; i++)
{

number = r.Next();
number = number % 36;
if (number < 10)
{
number += 48;
}
else
{
number += 55;
}
randomCode += ((char)number).ToString();
}
Response.Cookies.Add(new HttpCookie("CheckCode", randomCode));
return randomCode;
}

/// <summary>
/// 产生中文的随机验证码，可选用
/// </summary>
/// <returns></returns>
string GeberateChineseCheckCode(int strLength)
{
string[] rBase = new String[16] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };
Random rnd = new Random();
object[] bytes = new object[strLength];
for (int i = 0; i < strLength; i++)
{
//区位码第1位
int r1 = rnd.Next(11, 14);
string str_r1 = rBase[r1].Trim();
//区位码第2位
rnd = new Random(r1 * unchecked((int)DateTime.Now.Ticks) + i);//更换随机数发生器的种子避免产生重复值
int r2;
if (r1 == 13)
{
r2 = rnd.Next(0, 7);
}
else
{
r2 = rnd.Next(0, 16);
}
string str_r2 = rBase[r2].Trim();
//区位码第3位
rnd = new Random(r2 * unchecked((int)DateTime.Now.Ticks) + i);
int r3 = rnd.Next(10, 16);
string str_r3 = rBase[r3].Trim();
//区位码第4位
rnd = new Random(r3 * unchecked((int)DateTime.Now.Ticks) + i);
int r4;
if (r3 == 10)
{
r4 = rnd.Next(1, 16);
}
else if (r3 == 15)
{
r4 = rnd.Next(0, 15);
}
else
{
r4 = rnd.Next(0, 16);
}
string str_r4 = rBase[r4].Trim();
//定义两个字节变量存储产生的随机汉字区位码
byte byte1 = Convert.ToByte(str_r1 + str_r2, 16);
byte byte2 = Convert.ToByte(str_r3 + str_r4, 16);
//将两个字节变量存储在字节数组中
byte[] str_r = new byte[] { byte1, byte2 };
//将产生的一个汉字的字节数组放入object数组中
bytes.SetValue(str_r, i);
}
//获取GB2312编码页（表）
Encoding gb = Encoding.GetEncoding("gb2312");
string temp;
string result = string.Empty;
for (int i = 0; i < strLength; i++)
{
temp = gb.GetString((byte[])Convert.ChangeType(bytes[i], typeof(byte[])));
result += temp;
}
return result;
}

[解决办法]

HTML code

 <asp:ImageButton ID="ImgValidateCode" TabIndex="5" ToolTip="点击更换图片" ImageUrl="ValidateCode.aspx"                                            OnClick="ImgValidateCode_Click" runat="server" />