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 = 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 = 40;
    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 = { "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), 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)
    {
        Random CheckNum = new Random();
       
        string code = "";

        for (int i = 0; i < codeLen; i++)
        {
          if(i%2==0)
              code += (Convert.ToChar(CheckNum.Next(97, 122))).ToString();
          else
              code += CheckNum.Next(0, 9).ToString();
        }

        return code;
    }
    public string CreateVerifyCode()
    {
        return CreateVerifyCode(4);
    }
    #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(60000);
        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>