3种验证码示例(代码)(数字,数字字母混和,汉字)

Default.aspx

<table>
  <tr>
          <td class="style1">
              &nbsp;(验证码测试)</td>
          <td>
          &nbsp; <asp:Label
                  ID="Label1" runat="server"></asp:Label>
          &nbsp;
              <asp:Image ID="Image1" runat="server" Height="22px" ImageUrl="~/ValidNums.aspx" Width="58px" />&nbsp;
              <asp:Image ID="Image2" runat="server" Height="22px" ImageUrl="~/GetValid.aspx" Width="58px" /></td>
      </tr>  <tr>
          <td class="style1">
              &nbsp;
          </td>
          <td>
              &nbsp;&nbsp;<asp:Button ID="Button1" runat="server" Text="登录" OnClick="btnOK_Click" />
              &nbsp;&nbsp;
              <asp:Button ID="Button2" runat="server" Text="取消" />
          </td>
      </tr>
  </table>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            string getNums = GetVali();
            Label1.Text = getNums;
        }
    }

    /// <summary>
    /// 随机生成4位数
    /// </summary>
    /// <returns>返回生成的随机数</returns>
    public string GetVali()
    {
        string strsvali = "0,1,2,3,4,5,6,7,8,9";
        string[] ValiArray = strsvali.Split(',');
        string ReturnNum = "";
        int nums = -1;
        Random vrand = new Random();
        for (int n = 1; n < 5; n++)
        {
            if (nums != -1)
            {
                vrand = new Random(n * nums * unchecked((int)DateTime.Now.Ticks));
            }
            int t = vrand.Next(10);
            nums = t;
            ReturnNum += ValiArray[t];
        }
        Session["Valid"] = ReturnNum;
        return ReturnNum;
    }
    protected void btnOK_Click(object sender, EventArgs e)
    {
        if (Session["Valid"].ToString() == TextBox3.Text)
        {
            ClientScript.RegisterStartupScript(this.GetType(),"ss","<script>alert('您已经成功通过登录验证！')</script>");
        }
        else
        {
            ClientScript.RegisterStartupScript(this.GetType(), "ss", "<script>alert('您输入的验证码错误！')</script>");
        }
    }
}

GetValid.aspx

(可以直接将该页面作为源赋值给ImageUrl)

前台为空，后台代码如下：

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
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.Xml.Linq;
using System.Text;
using System.Drawing;

public partial class GetValid : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            string validateNum = GetValids();                 //成生4位随机字符串
            CreateImage(validateNum);                         //将生成的随机字符串绘成图片
            Session["ValidNums"] = validateNum;               //保存验证码
        }
    }
    public static  string GetValids()
    {
        //获取GB2312编码页（表）
        Encoding gb = Encoding.GetEncoding("gb2312");

        //调用函数产生4个随机中文汉字编码
        object[] bytes = CreateRegionCode(4);

        //根据汉字编码的字节数组解码出中文汉字

        string s = String.Empty;
        foreach (object byt in bytes)
        {
            string str1 = gb.GetString((byte[])Convert.ChangeType(byt, typeof(byte[])));
            s = s + str1;
        }

        //输出的控制台
        return s;
    }
    public static object[] CreateRegionCode(int strlength)
    {
        //定义一个字符串数组储存汉字编码的组成元素
        string[] rBase = new String[16] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

        Random rnd = new Random();

        //定义一个object数组用来
        object[] bytes = new object[strlength];
        /*每循环一次产生一个含两个元素的十六进制字节数组，并将其放入bject数组中
         每个汉字有四个区位码组成
          区位码第1位和区位码第2位作为字节数组第一个元素
          区位码第3位和区位码第4位作为字节数组第二个元素
         */
        for (int i = 0; i < strlength; i++)
        {
            //区位码第1位
            int r1 = rnd.Next(11, 14);
            string str_r1 = rBase[r1].Trim();

            //区位码第2位
            rnd = new Random(r1 * unchecked((int)DateTime.Now.Ticks) + i);
            //更换随机数发生器的种子避免产生重复值
            int r2;
            if (r1 == 13)
            {
                r2 = rnd.Next(0, 8);
            }
            else
            {
                r2 = rnd.Next(0, 16);
            }
            string str_r2 = rBase[r2].Trim();

            //区位码第3位
            rnd = new Random(r2 * unchecked((int)DateTime.Now.Ticks) + i);
            int r3 = rnd.Next(10, 16);
            string str_r3 = rBase[r3].Trim();

            //区位码第4位
            rnd = new Random(r3 * unchecked((int)DateTime.Now.Ticks) + i);
            int r4;
            if (r3 == 10)
            {
                r4 = rnd.Next(1, 16);
            }
            else if (r3 == 15)
            {
                r4 = rnd.Next(0, 15);
            }
            else
            {
                r4 = rnd.Next(0, 16);
            }
            string str_r4 = rBase[r4].Trim();

            //定义两个字节变量存储产生的随机汉字区位码
            byte byte1 = Convert.ToByte(str_r1 + str_r2, 16);
            byte byte2 = Convert.ToByte(str_r3 + str_r4, 16);
            //将两个字节变量存储在字节数组中
            byte[] str_r = new byte[] { byte1, byte2 };

            //将产生的一个汉字的字节数组放入object数组中
            bytes.SetValue(str_r, i);

        }

        return bytes;

    }
        //生成图片
    private void CreateImage(string validateNum)
    {
        if (validateNum == null || validateNum.Trim() == String.Empty)
            return;
        //生成Bitmap图像
        System.Drawing.Bitmap image = new System.Drawing.Bitmap(validateNum.Length * 12 + 10, 22);
        Graphics g = Graphics.FromImage(image);

        try
        {
            //生成随机生成器
            Random random = new Random();

            //清空图片背景色
            g.Clear(Color.White);

            //画图片的背景噪音线
            for (int i = 0; i < 25; 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.Coral), x1, y1, x2, y2);
            }

            Font font = new System.Drawing.Font("Arial", 8);
            System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
            g.DrawString(validateNum, font, brush, 2, 2);

            //画图片的前景噪音点
            for (int i = 0; i < 100; i++)
            {
                int x = random.Next(image.Width);
                int y = random.Next(image.Height);
                image.SetPixel(x, y, Color.FromArgb(random.Next()));
            }

            //画图片的边框线
            g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);

            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            //将图像保存到指定的流
            image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
            Response.ClearContent();
            Response.ContentType = "image/Gif";
            Response.BinaryWrite(ms.ToArray());
        }
        finally
        {
            g.Dispose();
            image.Dispose();
        }
    }
}

ValidNums.aspx

(可以直接将该页面作为源赋值给ImageUrl)

前台为空，后台代码如下：

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
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.Xml.Linq;
using System.Drawing;

public partial class ValidNums : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            string validateNum = CreateRandomNum(4);          //成生4位随机字符串
            CreateImage(validateNum);                         //将生成的随机字符串绘成图片
            Session["ValidNums"] = validateNum;               //保存验证码
        }
    }
    //生成随机字符串
    private string CreateRandomNum(int NumCount)
    {
        string allChar = "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,W,X,Y,Z";
        string[] allCharArray = allChar.Split(',');//拆分成数组
        string randomNum = "";
        int temp = -1;//记录上次随机数的数值，尽量避免产生几个相同的随机数
        Random rand = new Random();
        for (int i = 0; i < NumCount; i++)
        {
            if (temp != -1)
            {
                rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
            }
            int t = rand.Next(35);
            if (temp == t)
            {
                return CreateRandomNum(NumCount);
            }
            temp = t;
            randomNum += allCharArray[t];
        }
        return randomNum;
    }
    //生成图片
    private void CreateImage(string validateNum)
    {
        if (validateNum == null || validateNum.Trim() == String.Empty)
            return;
        //生成Bitmap图像
        System.Drawing.Bitmap image = new System.Drawing.Bitmap(validateNum.Length * 12 + 10, 22);
        Graphics g = Graphics.FromImage(image);

        try
        {
            //生成随机生成器
            Random random = new Random();

            //清空图片背景色
            g.Clear(Color.White);

            //画图片的背景噪音线
            for (int i = 0; i < 25; 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.Coral), x1, y1, x2, y2);
            }

            Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
            System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
            g.DrawString(validateNum, font, brush, 2, 2);

            //画图片的前景噪音点
            for (int i = 0; i < 100; i++)
            {
                int x = random.Next(image.Width);
                int y = random.Next(image.Height);
                image.SetPixel(x, y, Color.FromArgb(random.Next()));
            }

            //画图片的边框线
            g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);

            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            //将图像保存到指定的流
            image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
            Response.ClearContent();
            Response.ContentType = "image/Gif";
            Response.BinaryWrite(ms.ToArray());
        }
        finally
        {
            g.Dispose();
            image.Dispose();
        }
    }
}

以上是3种验证码的全部代码。

另外也可以使用ashx请求验证码的方式，本示例仅使用Session存值处理。