[转]asp.net(c#)生成验证码 点击可刷新

先建一张生成验证码的网页CheckCode.aspx:

CheckCode.aspx.cs代码如下

添加引用:

using System.IO;

using System.Drawing;

using System.Drawing.Imaging;

using System.Drawing.Drawing2D;

public partial class Default2 : System.Web.UI.Page

{

    private Bitmap validateimage;

    private Graphics g;

    protected void Page_Load(object sender, EventArgs e)

    {

        Response.BufferOutput = true;  //特别注意

        Response.Cache.SetExpires(DateTime.Now.AddMilliseconds(-1));//特别注意

        Response.Cache.SetCacheability(HttpCacheability.NoCache);//特别注意

        Response.AppendHeader("  Pragma", "No-Cache"); //特别注意

        string VNum = MakeValidateCode();

        Session["VNum"] = VNum;//取得验证码，以便后来验证

        ValidateCode(VNum);

    }

    public void ValidateCode(string VNum)

    {

        validateimage = new Bitmap(60, 20, PixelFormat.Format24bppRgb);

        g = Graphics.FromImage(validateimage);

        g.FillRectangle(new LinearGradientBrush(new Point(0, 0), new Point(110, 20), Color.FromArgb(240, 255, 255, 255), Color.FromArgb(240, 255, 255, 255)), 0, 0, 200, 200); //矩形框

        g.DrawString(VNum, new Font("arial", 11), new SolidBrush(Color.Red), new PointF(6, 0));//字体/颜色

        g.Save();

        MemoryStream ms = new MemoryStream();

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

        Response.ClearContent();

        Response.C;

        Response.BinaryWrite(ms.ToArray());

        Response.End();

    }

    string MakeValidateCode()

    {

        char[] s = new char[] { '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', 'v', 'w', 'x', 'y', 'z','A','B', 'C','D','E','F','G','H','I','J','K','L','M','N','P','Q','I','S','T','U','V','W','X','Y','Z'};//枚举数组

        string num = "";

        Random r = new Random();

        for (int i = 0; i < 5; i++)

        {

            num += s[r.Next(0, s.Length)].ToString();

        }

        return num;

    }

}

然后是显示验证码的页面 的html中加入<img src="Default2.aspx"  id="yzm" alt="点击刷新"  />

在</head>之前一行加入javascript脚本语言如下(当然写在JS文件里面更好):

<script type="text/javascript">

function reloadcode(){

document.getElementById("yzm").src ="CheckCode.aspx";

}

</script>