ASP.NET网页验证码常用方法

验证码生产类

 using System;
 using System.Data;
 using System.Configuration;

 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;

 using System.Drawing;
 using System.IO;
 using System.Drawing.Imaging;

 /// <summary>
 /// Summary description for validatedCode
 /// </summary>
 public class ValidatedCode
 {
     #region  验证码长度(默认4个验证码的长度)
     int length = ;
     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 = ;
     public int FontSize
     {
         get { return fontSize; }
         set { fontSize = value; }
     }
     #endregion

     #region 边框补(默认1像素)
     int padding = ;
     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 = { "Arial", "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;

     /// <summary>
     /// 正弦曲线Wave扭曲图片（Edit By 51aspx.com）
     /// </summary>
     /// <param name="srcBmp">图片路径</param>
     /// <param name="bXDir">如果扭曲则选择为True</param>
     /// <param name="nMultValue">波形的幅度倍数，越大扭曲的程度越高，一般为3</param>
     /// <param name="dPhase">波形的起始相位，取值区间[0-2*PI)</param>
     /// <returns></returns>
     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), , , destBmp.Width, destBmp.Height);
         graph.Dispose();

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

         for (int i = ; i < destBmp.Width; i++)
         {
             for (int j = ; j < destBmp.Height; j++)
             {
                 double dx = ;
                 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 = , nOldY = ;
                 nOldX = bXDir ? i + (int)(dy * dMultValue) : i;
                 nOldY = bXDir ? j : j + (int)(dy * dMultValue);

                 System.Drawing.Color color = srcBmp.GetPixel(i, j);
                 if (nOldX >=  && nOldX < destBmp.Width
                  && nOldY >=  && 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) +  + Padding * ;
         int imageHeight = fSize *  + 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, );
             int c = Length * ;

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

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

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

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

         Font f;
         Brush b;

         int cindex, findex;

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

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

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

             left = i * fWidth;

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

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

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

         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)
     {
         Random CheckNum = new Random();

         string code = "";

         for (int i = ; i < codeLen; i++)
         {
           if(i%==)
               code += (Convert.ToChar(CheckNum.Next(, ))).ToString();
           else
               code += CheckNum.Next(, ).ToString();
         }

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

验证码显示页面

 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;

 using System.Drawing.Drawing2D;
 using System.Drawing;
 using System.Drawing.Imaging;
 using System.IO;
 using Px_CSLibrary.Public;
 public partial class CheckCode : System.Web.UI.Page
 {

     protected void Page_Load(object sender, EventArgs e)
     {
         ValidatedCode v = new ValidatedCode();
         string checkNum = v.CreateVerifyCode();            //取随机码
         Session["Checkcode"] = checkNum;
         HttpCookie cookCode = new HttpCookie("Check");
         cookCode.Values.Add("code", checkNum);//把随机验证码保存Cookie
         cookCode.Expires = DateTime.Now.AddMilliseconds();
         Response.Cookies.Add(cookCode);

         v.CreateImageOnPage(checkNum, this.Context);       // 输出图片  

     }

 }

页面标签引用

<dd> <img id="CheckCode" alt="验证码" width="85px" height="25px" style="cursor: pointer" src="CheckCode.aspx" onclick="GetCode()" /></dd>
<dd>
<a href="javascript:void(0)" onclick="GetCode();">刷新</a>
</dd>