验证码几个小例

例一：

在网站要目录下添加ValidateCode.aspx,路径自己定。

ValidateCode.aspx：

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

ValidateCode.aspx.cs：

using System;

using System.Collections.Generic;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Drawing;

using System.IO;

using System.Drawing.Imaging;


public partial class ValidateCode_ValidateCode : System.Web.UI.Page

{

    private int letterWidth = 15;//单个字体的宽度范围

    private int letterHeight = 27;//单个字体的高度范围

    private int letterCount = 5;//验证码位数

    private char[] chars = "23456789QWERTYUPASDFGHJKLZXCVBNMqwertyupasdfghjkzxcvbnm".ToCharArray();

    private string[] fonts = { "Arial", "Georgia" };

    /// <summary>

    /// 产生波形滤镜效果

    /// </summary>

    private const double PI = 3.1415926535897932384626433832795;

    private const double PI2 = 6.283185307179586476925286766559;

    protected void Page_Load(object sender, EventArgs e) {

        //防止网页后退--禁止缓存

        Response.Expires = 0;

        Response.Buffer = true;

        Response.ExpiresAbsolute = DateTime.Now.AddSeconds(-1);

        Response.AddHeader("pragma", "no-cache");

        Response.CacheControl = "no-cache";

        string str_ValidateCode = GetRandomNumberString(letterCount);

        HttpCookie objCookie = new HttpCookie("ValidateCode");

        objCookie.Value = str_ValidateCode.ToLower();

        objCookie.Path = "/";

        objCookie.Expires = DateTime.Now.AddSeconds(1200);

        Response.Cookies.Add(objCookie);

        CreateImage(str_ValidateCode);


}

    public void CreateImage(string checkCode) {

        int int_ImageWidth = checkCode.Length * letterWidth + 5;

        Random newRandom = new Random();

        Bitmap image = new Bitmap(int_ImageWidth, letterHeight);

        Graphics g = Graphics.FromImage(image);

        //生成随机生成器

        Random random = new Random();

        //白色背景

        g.Clear(Color.White);

        //画图片的背景噪音线

        for (int i = 0; i < 10; 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.Silver), x1, y1, x2, y2);

        }


//画图片的前景噪音点

        for (int i = 0; i < 10; i++) {

            int x = random.Next(image.Width);

            int y = random.Next(image.Height);


image.SetPixel(x, y, Color.FromArgb(random.Next()));

        }

        //随机字体和颜色的验证码字符


int findex;

        for (int int_index = 0; int_index < checkCode.Length; int_index++) {

            findex = newRandom.Next(fonts.Length - 1);

            string str_char = checkCode.Substring(int_index, 1);

            Brush newBrush = new SolidBrush(GetRandomColor());

            Point thePos = new Point(int_index * letterWidth + 1 + newRandom.Next(3), 1 + newRandom.Next(3));//5+1+a+s+p+x

            g.DrawString(str_char, new Font(fonts[findex], 14, FontStyle.Bold), newBrush, thePos);

        }

        //灰色边框

        g.DrawRectangle(new Pen(Color.LightGray, 1), 0, 0, int_ImageWidth - 1, (letterHeight - 1));

        //图片扭曲

        //image = TwistImage(image, true, 3, 4);

        //将生成的图片发回客户端

        MemoryStream ms = new MemoryStream();

        image.Save(ms, ImageFormat.Png);

        Response.ClearContent(); //需要输出图象信息 要修改HTTP头

        Response.ContentType = "image/Png";

        Response.BinaryWrite(ms.ToArray());

        g.Dispose();

        image.Dispose();

    }

    /// <summary>

    /// 正弦曲线Wave扭曲图片

    /// </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;

    }

    public Color GetRandomColor() {

        Random RandomNum_First = new Random((int)DateTime.Now.Ticks);

        System.Threading.Thread.Sleep(RandomNum_First.Next(50));

        Random RandomNum_Sencond = new Random((int)DateTime.Now.Ticks);

        int int_Red = RandomNum_First.Next(210);

        int int_Green = RandomNum_Sencond.Next(180);

        int int_Blue = (int_Red + int_Green > 300) ? 0 : 400 - int_Red - int_Green;

        int_Blue = (int_Blue > 255) ? 255 : int_Blue;

        return Color.FromArgb(int_Red, int_Green, int_Blue);

    }

    //  生成随机数字字符串

    public string GetRandomNumberString(int int_NumberLength) {

        Random random = new Random();

        string validateCode = string.Empty;

        for (int i = 0; i < int_NumberLength; i++)

            validateCode += chars[random.Next(0, chars.Length)].ToString();

        return validateCode;

    }

}

使用时：

放在页面前
<span>验证码：</span>

<input name="txtCode" runat="server" type="text" id="txtCode"
class="txtinput1" />
<img class="txtverity"
onclick="this.src=this.src+‘?‘" src="ValidateCode/ValidateCode.aspx"
style="cursor: pointer" alt="看不清楚，换一张" title="看不清楚，换一张" />

//onclick="this.src=‘ValifyCode.aspx?r=‘ + Math.random();

放在页面后
protected void btnSendMsg_Click(object sender, EventArgs e)
{
if (Request.Cookies["ValidateCode"] == null)
{
ScriptManager.RegisterStartupScript(this, GetType(), "msg",
"alert(‘您的浏览器设置已被禁用 Cookies，您必须设置浏览器允许使用 Cookies 选项后才能使用本系统。‘)", true);

return;
}
else {

if (string.Compare(Request.Cookies["ValidateCode"].Value,
txtCode.Value.Trim().ToLower(), true) == 0)
{
insertMsgToUs();
}
else
{
ScriptManager.RegisterStartupScript(this, GetType(), "msg",
"alert(‘验证码不正确!‘)", true);
}
}
}

例二：

在网站根目录下添加自定义控件VerifyImage.ashx：

<%@ WebHandler Language="C#"  Class="VerifyImage" %>

using System;

using System.Data;

using System.Configuration;

using System.Collections;

using System.Collections.Generic;

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.Drawing;


/// <summary>

    /// 生成验证码

    /// </summary>

    public  class VerifyImage : IHttpHandler

    {

        public void ProcessRequest(HttpContext context)

        {

            context.Response.ContentType = "text/plain";


VerifyImage v = new VerifyImage();

            context.Response.Cache.SetCacheability(HttpCacheability.NoCache);//如不加，单击验证图片＇看不清换一张＇


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, context);        // 输出图片


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

        }


public bool IsReusable

        {

            get

            {

                return false;

            }

        }


#region 验证码长度(默认6个验证码的长度)

        int length = 5;

        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 = 12;

        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 = "1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,j,k,m,n,p,q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,J,K,M,N,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

        /// </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

            //image = TwistImage(image, true, 8, 4);

            image = TwistImage(image, true, 0, 0);


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

    }

使用时：

放在页面前
<span>验证码：</span>

<input name="txtCode" runat="server" type="text" id="txtCode"
class="txtinput1" />
<img src="VerifyImage.ashx" class="txtverity"
onclick="this.src=this.src+‘?‘" alt="点击刷新验证码"/>

放在页面后
protected void btnSendMsg_Click(object sender, EventArgs e)
{
if (Request.Cookies["VerifyCode"] == null)
{
ScriptManager.RegisterStartupScript(this, GetType(), "msg",
"alert(‘您的浏览器设置已被禁用 Cookies，您必须设置浏览器允许使用 Cookies 选项后才能使用本系统。‘)", true);

return;
}
else {

if (string.Compare(Request.Cookies["VerifyCode"].Value,
txtCode.Value.Trim().ToUpper(), true) == 0)
{
insertMsgToUs();
}
else
{
ScriptManager.RegisterStartupScript(this, GetType(), "msg",
"alert(‘验证码不正确!‘)", true);
}
}
}

例三：

添加ValidateCode.aspx，

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Drawing;

using System.Drawing.Imaging;

using System.IO;


public partial class ValidateCode : System.Web.UI.Page

{

    private void CreateImage(string checkCode)

        {

            int width = checkCode.Length * 14;

            Bitmap image = new Bitmap(width, 20);

            Graphics graphics = Graphics.FromImage(image);

            Font font = new Font("Arial ", 10f);

            Brush brush = new SolidBrush(Color.Black);

            Brush brush2 = new SolidBrush(Color.FromArgb(0xa6, 8, 8));

            graphics.Clear(ColorTranslator.FromHtml("#99C1CB"));

            char[] chArray = checkCode.ToCharArray();

            for (int i = 0; i < chArray.Length; i++)

            {

                if ((chArray[i] >= ‘0‘) && (chArray[i] <= ‘9‘))

                {

                    graphics.DrawString(chArray[i].ToString(), font, brush2, (float) (3 + (i * 12)), 3f);

                }

                else

                {

                    graphics.DrawString(chArray[i].ToString(), font, brush, (float) (3 + (i * 12)), 3f);

                }

            }

            MemoryStream stream = new MemoryStream();

            image.Save(stream, ImageFormat.Jpeg);

            base.Response.Cache.SetNoStore();

            base.Response.ClearContent();

            base.Response.ContentType = "image/Jpeg";

            base.Response.BinaryWrite(stream.ToArray());

            graphics.Dispose();

            image.Dispose();

        }


private string CreateRandomCode(int codeCount)

        {

            string[] strArray = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,i,J,K,M,N,P,Q,R,S,T,U,W,X,Y,Z".Split(new char[] { ‘,‘ });

            string str2 = "";

            int num = -1;

            Random random = new Random();

            for (int i = 0; i < codeCount; i++)

            {

                if (num != -1)

                {

                    random = new Random((i * num) * ((int) DateTime.Now.Ticks));

                }

                int index = random.Next(0x23);

                if (num == index)

                {

                    return this.CreateRandomCode(codeCount);

                }

                num = index;

                str2 = str2 + strArray[index];

            }

            return str2;

        }


private string GetRandomCode(int CodeCount)

        {

            string[] strArray = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,i,J,K,M,N,P,Q,R,S,T,U,W,X,Y,Z".Split(new char[] { ‘,‘ });

            string str2 = "";

            int num = -1;

            Random random = new Random();

            for (int i = 0; i < CodeCount; i++)

            {

                if (num != -1)

                {

                    random = new Random((num * i) * ((int) DateTime.Now.Ticks));

                }

                int index = random.Next(0x21);

                while (num == index)

                {

                    index = random.Next(0x21);

                }

                num = index;

                str2 = str2 + strArray[index];

            }

            return str2;

        }


protected void Page_Load(object sender, EventArgs e)

        {

            string randomCode = this.GetRandomCode(4);

            this.Session["CheckCode"] = randomCode;

            this.SetPageNoCache();

            this.CreateImage(randomCode);

        }


private void SetPageNoCache()

        {

            base.Response.Buffer = true;

            base.Response.ExpiresAbsolute = DateTime.Now.AddSeconds(-1.0);

            base.Response.Expires = 0;

            base.Response.CacheControl = "no-cache";

            base.Response.AppendHeader("Pragma", "No-Cache");

        }

}

页面前面：
<script type="text/javascript">
function
newGuid() {
var guid = "";
for (var i = 1; i <=
32; i++) {
var n = Math.floor(Math.random() *
16.0).toString(16);
guid += n;
if ((i ==
8) || (i == 12) || (i == 16) || (i == 20))
guid +=
"-";
}
return guid;
}
function
ChangeCode() {
var myImg =
document.getElementById("ImageCheck");
myImg.src =
"ValidateCode.aspx?flag=" + newGuid();
return false;

}
</script>

<input name="CheckCode" class="txtinput1" runat="server" type="text"
id="CheckCode"/>
<img id="ImageCheck" onclick="ChangeCode()"
src="ValidateCode.aspx" alt="看不清楚，换一张" title="看不清楚，换一张" />

页面后面：
protected void btnSendMsg_Click(object sender, EventArgs e)
{
if ((this.Session["CheckCode"] != null) &&
(this.Session["CheckCode"].ToString() != "")) {
if
(this.Session["CheckCode"].ToString().ToLower() !=
this.CheckCode.Value.ToLower()) {
//this.lblMsg.Text =
"验证码错误!";
ScriptManager.RegisterStartupScript(this, GetType(), "msg",
"alert(‘验证码不正确!‘)", true);
this.Session["CheckCode"] =
null;
return;
}
this.Session["CheckCode"] =
null;
insertMsgToUs();
}
else
{
base.Response.Redirect("Login.aspx");
}
}

例四：

verificationcode.aspx.cs：

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;


using System.Drawing;

using System.Drawing.Imaging;

using System.Drawing.Drawing2D;

using System.IO;

public partial class verificationcode : System.Web.UI.Page

{

    protected void Page_Load(object sender, EventArgs e) {

        Response.Cache.SetCacheability(HttpCacheability.NoCache);

        string vVerificationCode = RandomCode("verificationcode", 4, true);

        Add("verificationcode", vVerificationCode.ToLower());   //Session中保存验证码

        CreateImage(vVerificationCode);

    }

    /// <summary>

    /// 从字符串里随机得到，规定个数的字符串.

    /// </summary>

    /// <param name="allChar"></param>

    /// <param name="CodeCount"></param>

    /// <param name="tSleep">是否要在生成前将当前线程阻止以避免重复</param>

    /// <returns></returns>

    public static string RandomCode(string byChar, int CodeCount, bool tSleep) {

        string randomChar = "";

        switch (byChar) {

            case "num":

                randomChar = "1,2,3,4,5,6,7,8,9";

                break;

            case "maxen":

                randomChar = "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";

                break;

            case "minien":

                randomChar = "a,b,c,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z";

                break;

            case "minien&num":

                randomChar = "1,2,3,4,5,6,7,8,9,a,b,c,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z";

                break;

            case "all":

                randomChar = "1,2,3,4,5,6,7,8,9,a,b,c,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";

                break;

            case "verificationcode":

                randomChar = "2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,U,V,W,X,Y,Z";

                break;

            default:

                randomChar = byChar;

                break;

        }

        randomChar = randomChar.Replace(",", "");

        string RandomCode = "";

        if (tSleep) {

            System.Threading.Thread.Sleep(3);

        }

        char[] allCharArray = randomChar.ToCharArray();

        int n = allCharArray.Length;

        System.Random random = new Random(~unchecked((int)DateTime.Now.Ticks));

        for (int i = 0; i < CodeCount; i++) {

            int rnd = random.Next(0, n);

            RandomCode += allCharArray[rnd];

        }

        return RandomCode;

    }

    /// <summary>

    /// 添加Session，有效期为20分钟

    /// </summary>

    /// <param name="strSessionName">Session对象名称</param>

    /// <param name="strValues">Session值数组</param>

    public static void Add(string strSessionName, string strValue) {

        HttpContext.Current.Session[strSessionName] = strValue;

        HttpContext.Current.Session.Timeout = 20;

    }

    #region 验证码

        ///  <summary>

        ///  创建验证码图片

        ///  </summary>

        ///  <param  name="randomcode">验证码</param>

        private void CreateImage(string randomcode)

        {

            int randAngle = 40; //随机转动角度

            int mapwidth = (int)(randomcode.Length * 18);

            Bitmap map = new Bitmap(mapwidth, 24);//创建图片背景

            Graphics graph = Graphics.FromImage(map);

            graph.Clear(Color.White);//清除画面，填充背景

            //graph.DrawRectangle(new Pen(Color.Silver, 0), 0, 0, map.Width - 1, map.Height - 1);//画一个边框

            Random rand = new Random();

            //验证码旋转，防止机器识别

            char[] chars = randomcode.ToCharArray();//拆散字符串成单字符数组

            //文字距中

            StringFormat format = new StringFormat(StringFormatFlags.NoClip);

            format.Alignment = StringAlignment.Center;

            format.LineAlignment = StringAlignment.Center;

            //定义颜色

            Color[] c = { Color.Black, Color.Red, Color.Blue, Color.Green,

                            Color.Orange, Color.Brown, Color.DarkBlue };

            //画图片的背景噪音线

            for (int i = 0; i < 2; i++)

            {

                int x1 = rand.Next(10);

                int x2 = rand.Next(map.Width - 10, map.Width);

                int y1 = rand.Next(map.Height);

                int y2 = rand.Next(map.Height);

                graph.DrawLine(new Pen(c[rand.Next(7)]), x1, y1, x2, y2);

            }

            for (int i = 0; i < chars.Length; i++)

            {

                int cindex = rand.Next(7);

                int findex = rand.Next(5);

                Font f = new System.Drawing.Font("Arial", 18, System.Drawing.FontStyle.Regular);//字体样式(参数2为字体大小)

                Brush b = new System.Drawing.SolidBrush(c[cindex]);

                Point dot = new Point(12, 16);

                float angle = rand.Next(-randAngle, randAngle);//转动的度数

                graph.TranslateTransform(dot.X, dot.Y);//移动光标到指定位置

                graph.RotateTransform(angle);

                graph.DrawString(chars[i].ToString(), f, b, 1, 1, format);

                graph.RotateTransform(-angle);//转回去

                graph.TranslateTransform(2, -dot.Y);//移动光标到指定位置

            }

            //生成图片

            System.IO.MemoryStream ms = new System.IO.MemoryStream();

            map.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);

            Response.ClearContent();

            Response.ContentType = "image/gif";

            Response.BinaryWrite(ms.ToArray());

            graph.Dispose();

            map.Dispose();

        }

        #endregion

}

页面前面
<input name="txtCode" runat="server" type="text" id="txtCode"
class="txtinput1" />
<img src="verificationcode.aspx"
onclick="this.src=‘verificationcode.aspx?r=‘ + Math.random();" alt="点击刷新验证码"
style="cursor: pointer;"/>

页面后面
protected void btnSendMsg_Click(object sender, EventArgs e)
{
if ((this.Session["verificationcode"] != null) &&
(this.Session["verificationcode"].ToString() != "")) {
if
(this.Session["verificationcode"].ToString() != this.txtCode.Value.ToLower())
{
ScriptManager.RegisterStartupScript(this, GetType(), "msg",
"alert(‘验证码不正确!‘)", true);
this.Session["verificationcode"] =
null;
return;
}
this.Session["verificationcode"] =
null;
insertMsgToUs();
}
else
{
base.Response.Redirect("Login.aspx");
}
}

时间： 2024-10-10 08:27:48

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