在ASP.NET中用C#做一个图片验证码?

新建一个aspx页面，内容复制下面的，页面中什么都不要些。保持原样。
在需要验证码的页面加入：
样式自己调

using System;
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;

public partial class VerifyCode : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{

VerifyCode v = new VerifyCode();

v.Length = this.length;
v.FontSize = this.fontSize;
v.Chaos = this.chaos;
v.BackgroundColor = this.backgroundColor;
v.ChaosColor = this.chaosColor;
v.CodeSerial = this.codeSerial;
v.Colors = this.colors;
v.Fonts = this.fonts;
v.Padding = this.padding;
string code = v.CreateVerifyCode(); //取随机码
v.CreateImageOnPage(code, this.Context); // 输出图片

Response.Cookies.Add(new HttpCookie("CheckCode", code.ToUpper()));// 使用Cookies取验证码的值

}

#region 验证码长度(默认6个验证码的长度)
int length = 4;
public int Length
{
get { return length; }
set { length = value; }
}
#endregion

#region 验证码字体大小(为了显示扭曲效果，默认40像素，可以自行修改)
int fontSize = 14;
public int FontSize
{
get { return fontSize; }
set { fontSize = value; }
}
#endregion

#region 边框补(默认1像素)
int padding = 2;
public int Padding
{
get { return padding; }
set { padding = value; }
}
#endregion

#region 是否输出燥点(默认不输出)
bool chaos = true;
public bool Chaos
{
get { return chaos; }
set { chaos = value; }
}
#endregion

#region 输出燥点的颜色(默认灰色)
Color chaosColor = Color.LightGray;
public Color ChaosColor
{
get { return chaosColor; }
set { chaosColor = value; }
}
#endregion

#region 自定义背景色(默认白色)
Color backgroundColor = Color.White;
public Color BackgroundColor
{
get { return backgroundColor; }
set { backgroundColor = value; }
}
#endregion

#region 自定义随机颜色数组
Color[] colors = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };
public Color[] Colors
{
get { return colors; }
set { colors = value; }
}
#endregion

#region 自定义字体数组
string[] fonts = { "Cambria", "Georgia" };
public string[] Fonts
{
get { return fonts; }
set { fonts = value; }
}
#endregion

#region 自定义随机码字符串序列(使用逗号分隔)
string codeSerial = "0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";
public string CodeSerial
{
get { return codeSerial; }
set { codeSerial = value; }
}
#endregion

#region 产生波形滤镜效果

private const double PI = 3.1415926535897932384626433832795;
private const double PI2 = 6.283185307179586476925286766559;

///

/// 正弦曲线Wave扭曲图片
///

/// 图片路径
/// 如果扭曲则选择为True
/// 波形的幅度倍数，越大扭曲的程度越高，一般为3
/// 波形的起始相位，取值区间[0-2*PI)
///
//public System.Drawing.Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)
//{
// System.Drawing.Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);

// // 将位图背景填充为白色
// System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(destBmp);
// graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), 0, 0, destBmp.Width, destBmp.Height);
// graph.Dispose();

// double dBaseAxisLen = bXDir ? (double)destBmp.Height : (double)destBmp.Width;

// for (int i = 0; i < destBmp.Width; i++)
// {
// for (int j = 0; j < destBmp.Height; j++)
// {
// double dx = 0;
// dx = bXDir ? (PI2 * (double)j) / dBaseAxisLen : (PI2 * (double)i) / dBaseAxisLen;
// dx += dPhase;
// double dy = Math.Sin(dx);

// // 取得当前点的颜色
// int nOldX = 0, nOldY = 0;
// nOldX = bXDir ? i + (int)(dy * dMultValue) : i;
// nOldY = bXDir ? j : j + (int)(dy * dMultValue);

// System.Drawing.Color color = srcBmp.GetPixel(i, j);
// if (nOldX >= 0 && nOldX < destBmp.Width
// && nOldY >= 0 && nOldY < destBmp.Height)
// {
// destBmp.SetPixel(nOldX, nOldY, color);
// }
// }
// }

// return destBmp;
//}

#endregion

#region 生成校验码图片
public Bitmap CreateImageCode(string code)
{
int fSize = FontSize;
int fWidth = fSize + Padding;

int imageWidth = (int)(code.Length * fWidth) + 4 + Padding * 2;
int imageHeight = fSize * 2 + Padding;

System.Drawing.Bitmap image = new System.Drawing.Bitmap(imageWidth, imageHeight);

Graphics g = Graphics.FromImage(image);

g.Clear(BackgroundColor);

Random rand = new Random();

//给背景添加随机生成的燥点
if (this.Chaos)
{

Pen pen = new Pen(ChaosColor, 0);
int c = Length * 10;

for (int i = 0; i < c; i++)
{
int x = rand.Next(image.Width);
int y = rand.Next(image.Height);

g.DrawRectangle(pen, x, y, 1, 1);
}
}

int left = 0, top = 0, top1 = 1, top2 = 1;

int n1 = (imageHeight - FontSize - Padding * 2);
int n2 = n1 / 4;
top1 = n2;
top2 = n2 * 2;

Font f;
Brush b;

int cindex, findex;

//随机字体和颜色的验证码字符
for (int i = 0; i < code.Length; i++)
{
cindex = rand.Next(Colors.Length - 1);
findex = rand.Next(Fonts.Length - 1);

f = new System.Drawing.Font(Fonts[findex], fSize, System.Drawing.FontStyle.Bold);
b = new System.Drawing.SolidBrush(Colors[cindex]);

if (i % 2 == 1)
{
top = top2;
}
else
{
top = top1;
}

left = i * fWidth;

g.DrawString(code.Substring(i, 1), f, b, left, top);
}

//画一个边框 边框颜色为Color.Gainsboro
g.DrawRectangle(new Pen(Color.Gainsboro, 0), 0, 0, image.Width - 1, image.Height - 1);
g.Dispose();

//产生波形（Add By 51aspx.com）
// image = TwistImage(image, true, 8, 4);

return image;
}
#endregion

#region 将创建好的图片输出到页面
public void CreateImageOnPage(string code, HttpContext context)
{
System.IO.MemoryStream ms = new System.IO.MemoryStream();
Bitmap image = this.CreateImageCode(code);

image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);

context.Response.ClearContent();
context.Response.ContentType = "image/Jpeg";
context.Response.BinaryWrite(ms.GetBuffer());

ms.Close();
ms = null;
image.Dispose();
image = null;
}
#endregion

#region 生成随机字符码
public string CreateVerifyCode(int codeLen)
{
if (codeLen == 0)
{
codeLen = Length;
}

string[] arr = CodeSerial.Split(',');

string code = "";

int randValue = -1;

Random rand = new Random(unchecked((int)DateTime.Now.Ticks));

for (int i = 0; i < codeLen; i++)
{
randValue = rand.Next(0, arr.Length - 1);

code += arr[randValue];
}

return code;
}
public string CreateVerifyCode()
{
return CreateVerifyCode(0);
}
#endregion
}

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="VerifyCode.aspx.cs" Inherits="VerifyCode" %>