生成验证码（纯数字）

前几天写了个数字与字母混合的验证码技术，今天写个纯数字的验证码。这里先写个类

CheckCode.cs

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.Drawing;



/// <summary>

/// CheckCode 的摘要说明

/// </summary>

public class CheckCode

{

    public CheckCode()

    {

        //

        // TODO: 在此处添加构造函数逻辑

        //

    }

    public static void DrawImage()

    {

        CheckCode img = new CheckCode();

        HttpContext.Current.Session["CheckCode"] = img.RndNum(4);

        img.checkCodes(HttpContext.Current.Session["CheckCode"].ToString());

    }

    /// <summary>

    /// 生成验证图片

    /// </summary>

    /// <param name="checkCode">验证字符</param>

    private void checkCodes(string checkCode)

    {

        int iwidth = (int)(checkCode.Length * 13);

        System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 23);

        Graphics g = Graphics.FromImage(image);

        g.Clear(Color.White);

        //定义颜色

        Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };

        //定义字体 

        string[] font = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" };

        Random rand = new Random();

        //随机输出噪点

        for (int i = 0; i < 50; i++)

        {

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

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

            g.DrawRectangle(new Pen(Color.LightGray, 0), x, y, 1, 1);

        }



        //输出不同字体和颜色的验证码字符

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

        {

            int cindex = rand.Next(7);

            int findex = rand.Next(5);



            Font f = new System.Drawing.Font(font[findex], 10, System.Drawing.FontStyle.Bold);

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

            int ii = 4;

            if ((i + 1) % 2 == 0)

            {

                ii = 2;

            }

            g.DrawString(checkCode.Substring(i, 1), f, b, 3 + (i * 12), ii);

        }

        //画一个边框

        g.DrawRectangle(new Pen(Color.Black, 0), 0, 0, image.Width - 1, image.Height - 1);



        //输出到浏览器

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

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

        HttpContext.Current.Response.ClearContent();

        //Response.ClearContent();

        HttpContext.Current.Response.ContentType = "image/Jpeg";

        HttpContext.Current.Response.BinaryWrite(ms.ToArray());

        g.Dispose();

        image.Dispose();

    }



    /// <summary>

    /// 生成随机的字母

    /// </summary>

    /// <param name="VcodeNum">生成字母的个数</param>

    /// <returns>string</returns>

    private string RndNum(int VcodeNum)

    {

        string Vchar = "0,1,2,3,4,5,6,7,8,9";

        string[] VcArray = Vchar.Split(',');

        string VNum = ""; //由于字符串很短，就不用StringBuilder了

        int temp = -1; //记录上次随机数值，尽量避免生产几个一样的随机数

        //采用一个简单的算法以保证生成随机数的不同

        Random rand = new Random();

        for (int i = 1; i < VcodeNum + 1; i++)

        {

            if (temp != -1)

            {

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

            }

            int t = rand.Next(VcArray.Length);

            if (temp != -1 && temp == t)

            {

                return RndNum(VcodeNum);

            }

            temp = t;

            VNum += VcArray[t];

        }

        return VNum;

    }

}

再建立一个引用类的页面checkCode.aspx前台不用写东西，后台引用我们创建的类的DrawImage()方法即可。

using System;

using System.Data;

using System.Configuration;

using System.Collections;

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;



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

{

    protected void Page_Load(object sender, EventArgs e)

    {

        CheckCode.DrawImage();

    }

}

下面我们在需要验证码的页面引用checkCode.aspx页面即可。
前台

                          <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+'?'" src="checkCode.aspx"

                                        style="width: 73px; height: 22px" align="left" />

                               <asp:ImageButton ID="imgBtnLogin" runat="server" ImageUrl="~/Images/Login.GIF" 

                            OnClick="imgBtnLogin_Click" />             

后台判断

    protected void imgBtnLogin_Click(object sender, ImageClickEventArgs e)

    {

        if(this.Validator.Text==Session["CheckCode"].ToString())

        {

          //。。。。

        }

        else

        {

            Response.Write("<script>alert('验证码输入错误，请重新输入！');Location='MumberValidate.aspx'</script>");

            return;

        }

    }

以上代码请根据实际情况作适当修改。