当前位置：首页 > 软件开发 > .NET > ASP.NET

生成验证码

来源：岁月联盟编辑：exp 时间：2012-05-29

CheckCode.aspx页面其实什么也不用写

<%@ Page Language="C#" CodeFile="CheckCode.aspx.cs" Inherits="ValidateCode" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">

    </form>
</body>
</html>

CheckCode.aspx.cs页面代码，生成验证码的主要部分

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 ValidateCode : System.Web.UI.Page
{
     private void Page_Load(object sender, System.EventArgs e)
     {
         this.CreateCheckCodeImage(GenerateCheckCode());
     }
     #region Web 窗体设计器生成的代码
     override protected void OnInit(EventArgs e)
     {
         //
         // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
         //
         InitializeComponent();
         base.OnInit(e);
     }

      /// <summary>
      /// 设计器支持所需的方法 - 不要使用代码编辑器修改
      /// 此方法的内容。
      /// </summary>
     private void InitializeComponent()
     {
         this.Load += new System.EventHandler(this.Page_Load);
     }
     #endregion

     private string GenerateCheckCode()
     {
         int number;
         char code;
         string checkCode = String.Empty;

System.Random random = new Random();

         for (int i = 0; i < 5; i++)
         {
             number = random.Next();

             if (number % 2 == 0)
                 code = (char)('0' + (char)(number % 10));
             else
                 code = (char)('A' + (char)(number % 26));

checkCode += code.ToString();
}

Session["CheckCodeImage"] = checkCode;

return checkCode;
}

     private void CreateCheckCodeImage(string checkCode)
     {
         if (checkCode == null || checkCode.Trim() == String.Empty)
             return;

System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22);
Graphics g = Graphics.FromImage(image);

         try
         {
             //生成随机生成器 www.2cto.com
             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.Silver), 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(checkCode, 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();
             image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
             Response.ClearContent();
             Response.ContentType = "image/Gif";
             Response.BinaryWrite(ms.ToArray());
         }
         finally
         {
             g.Dispose();
             image.Dispose();
         }
     }
}

下一步我们来引用上面的生成验证码页面（太简单不多说）
                       <asp:Label ID="labFlag" runat="server" Text="Label"></asp:Label>
                       <asp:TextBox ID="txtYz_Code" runat="server" MaxLength="5" Width="55px" BorderColor="Gray" BorderWidth="1px"></asp:TextBox>
                       <img title="看不清点击换一张" align="absMiddle" onclick="this.src=this.src+'?'" src="PassWord/CheckCode.aspx" />

后台判断
        if (String.Compare(Session["CheckCodeImage"].ToString(), this.txtYz_Code.Text.Trim().ToUpper(), true) != 0)
        {
            this.labFlag.text = "验证码错误，请输入正确的验证码。";
        }