產生驗證碼（純數字）

前幾天寫了個數字與字母混合的驗證碼技術，今天寫個純數位驗證碼。這裡先寫個類

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 的摘要說明/// </summary>public class CheckCode{    public CheckCode()    {        //        // TODO: 在此處添加建構函式邏輯        //    }    public static void DrawImage()    {        CheckCode img = new CheckCode();        HttpContext.Current.Session["CheckCode"] = img.RndNum(4);        img.checkCodes(HttpContext.Current.Session["CheckCode"].ToString());    }    /// <summary>    /// 產生驗證圖片    /// </summary>    /// <param name="checkCode">驗證字元</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);        //定義顏色        Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };        //定義字型         string[] font = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋體" };        Random rand = new Random();        //隨機輸出噪點        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);        }        //輸出不同字型和顏色的驗證碼字元        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);        }        //畫一個邊框        g.DrawRectangle(new Pen(Color.Black, 0), 0, 0, image.Width - 1, image.Height - 1);        //輸出到瀏覽器        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>    /// 產生隨機的字母    /// </summary>    /// <param name="VcodeNum">產生字母的個數</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 = ""; //由於字串很短，就不用StringBuilder了        int temp = -1; //記錄上次隨機數值，盡量避免生產幾個一樣的隨機數        //採用一個簡單的演算法以保證產生隨機數的不同        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;    }}

再建立一個引用類的頁面checkCode.aspx前台不用寫東西，後台引用我們建立的類的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();    }}

下面我們在需要驗證碼的頁面引用checkCode.aspx頁面即可。
前台

                          <asp:TextBox ID="Validator" runat="server" Width="150px" ></asp:TextBox>                          <img id="Img1" alt="看不清，請點擊我！" 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" />             

後台判斷

    protected void imgBtnLogin_Click(object sender, ImageClickEventArgs e)    {        if(this.Validator.Text==Session["CheckCode"].ToString())        {          //。。。。        }        else        {            Response.Write("<script>alert('驗證碼輸入錯誤，請重新輸入！');Location='MumberValidate.aspx'</script>");            return;        }    }

以上代碼請根據實際情況作適當修改。