asp.net生成验证码代码（纯中文）

using System; 
using System.Data; 
using System.Configuration; 
using System.Web; 
using System.Web.Security; 
using System.Web.UI; 
using System.Web.UI.WebControls; 
using System.Web.UI.WebControls.WebParts; 
using System.Web.UI.HtmlControls; 
using System.Text; //添加引用 
using System.Drawing; //添加引用 
/// <summary> 
/// CheckCode_Ch 的摘要说明 
/// </summary> 
public class CheckCode_Ch 
{ 
public CheckCode_Ch() 
{ 
// 
// TODO: 在此处添加构造函数逻辑 
// 
} 
private static object[] CreateString() 
{ 
//定义一个数组存储汉字编码的组成元素 
string[] str = new string[16] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" }; 
Random ran = new Random(); //定义一个随机数对象 
object[] bytes = new object[4]; 
for (int i = 0; i < 4; i++) 
{ 
//获取区位码第一位 
int ran1 = ran.Next(11, 14); 
string str1 = str[ran1].Trim(); 
//获取区位码第二位并防止数据重复 
ran = new Random(ran1 * unchecked((int)DateTime.Now.Ticks) + i); 
int ran2; 
if (ran1 == 13) 
{ 
ran2 = ran.Next(0, 7); 
} 
else 
{ 
ran2 = ran.Next(0, 16); 
} 
string str2 = str[ran2].Trim(); 
//获取区位码第三位 
ran = new Random(ran2 * unchecked((int)DateTime.Now.Ticks) + i); 
int ran3 = ran.Next(10, 16); 
string str3 = str[ran3].Trim(); 
//获取区位码第四位 
ran = new Random(ran3 * unchecked((int)DateTime.Now.Ticks) + i); 
int ran4; 
if (ran3 == 10) 
{ 
ran4 = ran.Next(1, 16); 
} 
else if (ran3 == 15) 
{ 
ran4 = ran.Next(0, 15); 
} 
else 
{ 
ran4 = ran.Next(0, 16); 
} 
string str4 = str[ran4].Trim(); 
//定义字节变量存储产生的随机汉字区位码 
byte byte1 = Convert.ToByte(str1 + str2, 16); 
byte byte2 = Convert.ToByte(str3 + str4, 16); 
byte[] stradd = new byte[] { byte1, byte2 }; 
//将产生的汉字字节放入数组 
bytes.SetValue(stradd, i); 
} 
return bytes; 
} 
private static string GetString() 
{ 
Encoding gb = Encoding.GetEncoding("gb2312"); 
object[] bytes = CreateString(); 
//根据汉字字节解码出中文汉字 
string str1 = gb.GetString((byte[])Convert.ChangeType(bytes[0], typeof(byte[]))); 
string str2 = gb.GetString((byte[])Convert.ChangeType(bytes[1], typeof(byte[]))); 
string str3 = gb.GetString((byte[])Convert.ChangeType(bytes[2], typeof(byte[]))); 
string str4 = gb.GetString((byte[])Convert.ChangeType(bytes[3], typeof(byte[]))); 
string str = str1 + str2 + str3 + str4; 
HttpContext.Current.Response.Cookies.Add(new HttpCookie("CheckCode", str)); 
return str; 
} 
public static void GraphicsImage() 
{ 
System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((GetString().Length * 22.5)), 22); 
Graphics g = Graphics.FromImage(image); //创建画布 
try 
{ 
//生成随机生成器 
Random random = new Random(); 
//清空图片背景色 
g.Clear(Color.White); 
//画图片的背景噪音线 
for (int i = 0; i < 1; i++) 
{ 
int x1 = random.Next(image.Width); 
int x2 = random.Next(image.Width); 
int y1 = random.Next(image.Height); 
int y2 = random.Next(image.Height); 
g.DrawLine(new Pen(Color.Black), x1, y1, x2, y2); 
} 
Font font = new System.Drawing.Font("Couriew New", 12, System.Drawing.FontStyle.Bold); 
System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush 
(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true); 
g.DrawString(GetString(), font, brush, 2, 2); 
//画图片的前景噪音点 
for (int i = 0; i < 50; i++) 
{ 
int x = random.Next(image.Width); 
int y = random.Next(image.Height); 
image.SetPixel(x, y, Color.FromArgb(random.Next())); 
} 
//画图片的边框线 
g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1); 
System.IO.MemoryStream ms = new System.IO.MemoryStream(); 
image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif); 
HttpContext.Current.Response.ClearContent(); 
HttpContext.Current.Response.ContentType = "image/Gif"; 
HttpContext.Current.Response.BinaryWrite(ms.ToArray()); 
} 
catch (Exception ms) 
{ 
HttpContext.Current.Response.Write(ms.Message); 
} 
} 
}

using System; 
using System.Collections; 
using System.Configuration; 
using System.Data; 
using System.Web; 
using System.Web.Security; 
using System.Web.UI; 
using System.Web.UI.HtmlControls; 
using System.Web.UI.WebControls; 
using System.Web.UI.WebControls.WebParts; 
public partial class UserValidator_ChineseCheckCode : System.Web.UI.Page 
{ 
protected void Page_Load(object sender, EventArgs e) 
{ 
CheckCode_Ch.GraphicsImage(); //调用方法生成四位汉字验证码 
} 
}

<asp:TextBox ID="Validator" runat="server" Width="150px" ></asp:TextBox> 
<img id="Img1" alt="看不清，请点击我！" onclick="this.src=this.src+&#39;?&#39;" src="ChineseCheckCode.aspx" 
style="width: 75px; height: 24px" align="left" /> 
<asp:ImageButton ID="imgBtnLogin" runat="server" ImageUrl="~/Images/Login.GIF" 
OnClick="imgBtnLogin_Click" />

protected void imgBtnLogin_Click(object sender, ImageClickEventArgs e) 
{ 
HttpCookie cookie = Request.Cookies["CheckCode"]; 
if (cookie.Value == this.Validator.Text.Trim()) 
{ 
//。。。 
} 
else 
{ 
Response.Write("<script>alert(&#39;验证码输入错误，请重新输入！&#39;);Location=&#39;ChineseCodeValidator.aspx&#39;</script>"); 
return; 
} 
}