生成图片验证码

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;

public partial class _Default : System.Web.UI.Page 
{
    
    protected void Page_Load(object sender, EventArgs e)
    {
                //BmpWeb.MyService imgsvr = new BmpWeb.MyService();
        //string strKey = "";
        //byte[] data = imgsvr.GenerateVerifyImage(7, ref strKey);
        //Response.OutputStream.Write(data, 0, data.Length);
        
        //System.IO.MemoryStream ms = new System.IO.MemoryStream(data);
        //System.Drawing.Image img = System.Drawing.Image.FromStream(ms);
        
        //img.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Bmp);

        string strKey = "";
        byte[] data = GenerateVerifyImage(5, ref strKey);

        //cookies
        Response.Cookies.Add(new HttpCookie("Img_CheckCode", strKey));
        Response.OutputStream.Write(data, 0, data.Length);

    }

    /**//// <summary>
    /// 将字节流转成图片数据
    /// </summary>
    /// <param name="imgData"></param>
    /// <returns></returns>
    private System.Drawing.Image convertByteToImg(byte[] imgData)
    {
        System.IO.MemoryStream ms = new System.IO.MemoryStream(imgData);
        System.Drawing.Image img = System.Drawing.Image.FromStream(ms);
        return img;
    }

    /**//// <summary>
    /// 生成图片验证码 可以作为web Services 调用
    /// </summary>
    /// <param name="nLen">验证码的长度</param>
    /// <param name="strKey">输出参数，验证码的内容</param>
    /// <returns>图片字节流</returns>
    public byte[] GenerateVerifyImage(int nLen, ref string strKey)
    {
        int nBmpWidth = 13 * nLen + 5;
        int nBmpHeight = 25;
        System.Drawing.Bitmap bmp = new System.Drawing.Bitmap(nBmpWidth, nBmpHeight);

        // 1. 生成随机背景颜色
        int nRed, nGreen, nBlue;  // 背景的三元色
        System.Random rd = new Random((int)System.DateTime.Now.Ticks);
        nRed = rd.Next(255) % 128 + 128;
        nGreen = rd.Next(255) % 128 + 128;
        nBlue = rd.Next(255) % 128 + 128;

        // 2. 填充位图背景
        System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(bmp);
        graph.FillRectangle(new SolidBrush(System.Drawing.Color.FromArgb(nRed, nGreen, nBlue))
         , 0
         , 0
         , nBmpWidth
         , nBmpHeight);


        // 3. 绘制干扰线条，采用比背景略深一些的颜色
        int nLines = 3;
        System.Drawing.Pen pen = new System.Drawing.Pen(System.Drawing.Color.FromArgb(nRed - 17, nGreen - 17, nBlue - 17), 2);
        for (int a = 0; a < nLines; a++)
        {
            int x1 = rd.Next() % nBmpWidth;
            int y1 = rd.Next() % nBmpHeight;
            int x2 = rd.Next() % nBmpWidth;
            int y2 = rd.Next() % nBmpHeight;
            graph.DrawLine(pen, x1, y1, x2, y2);
        }

        // 采用的字符集，可以随即拓展，并可以控制字符出现的几率
        string strCode = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890abcdefghijklmnopqrstuvwxyz";

        // 4. 循环取得字符，并绘制
        string strResult = "";
        for (int i = 0; i < nLen; i++)
        {
            int x = (i * 13 + rd.Next(3));
            int y = rd.Next(4) + 1;

            // 确定字体
            System.Drawing.Font font = new System.Drawing.Font("Courier New",
             12 + rd.Next() % 4,
             System.Drawing.FontStyle.Bold);
            char c = strCode[rd.Next(strCode.Length)];  // 随机获取字符
            strResult += c.ToString();

            // 绘制字符
            graph.DrawString(c.ToString(),
             font,
             new SolidBrush(System.Drawing.Color.FromArgb(nRed - 60 + y * 3, nGreen - 60 + y * 3, nBlue - 40 + y * 3)),
             x,
             y);
        }

        // 5. 输出字节流
        System.IO.MemoryStream bstream = new System.IO.MemoryStream();
        bmp.Save(bstream, System.Drawing.Imaging.ImageFormat.Jpeg);
        bmp.Dispose();
        graph.Dispose();

        strKey = strResult;
        byte[] byteReturn = bstream.ToArray();
        bstream.Close();

        return byteReturn;
    }

调动页面代码:

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>无标题页</title>
    <script type="text/javascript">
        function reloadcode(){ 
        document.getElementById("imgbmp").src ="Default.aspx?" + Math.random();
        } 
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        &nbsp;<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
         <img id="imgbmp" src="Default.aspx" alt= "看不清楚,换一个。" style="cursor : pointer;" onclick="reloadcode();" align="absmiddle" />
        <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Button" />
        <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label></div>
    </form>
</body>
</html>

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 Default2 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        if (CheckCodeCheck())
        {
            Label1.Text = "验证码相同";
        }
    }

    public bool CheckCodeCheck()
    {
        if (Request.Cookies["Img_CheckCode"] == null)
        {
            Label1.Text = "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。";
            Label1.Visible = true;
            return false;
        }

        if (String.Compare(Request.Cookies["Img_CheckCode"].Value, TextBox1.Text,false) != 0)
        {
            Label1.Text = "验证码错误，请输入正确的验证码。";
            Label1.Visible = true;
            return false;
        }
        return true;
    }
}