Asp.NET验证码控件

在网上搜罗了一些验证码的方法，觉得这个算是最好的了，并且做了个小Demo，我有个习惯是把类放在类库里，做成DLL,下面是代码，和这个DLL的下载地址：

1.编译生成的DLL下载地址：下载ValidaterPicture.dll   ，源文件如下：

ValidaterPictureClass.cs

---

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Drawing;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

namespace ValidaterPicture
{
    public class ValidaterPictureClass
    {
        public ValidaterPictureClass()
        {
            //
            // TODO: 在此处添加构造函数逻辑
            //
        }

        //验证码的字符串
        public static string ImageString;

 

        /// <summary>
        /// 绘制验证码图片方法
        /// </summary>
        public static void DrawImage()
        {
            ValidaterPictureClass img = new ValidaterPictureClass();
            ValidaterPictureClass.ImageString = img.RndNum(6);
            //HttpContext.Current.Session["CheckCode"] = ;

            img.CreateImages(img.RndNum(6));
        }

 

        /// <summary>
        /// 生成验证图片
        /// </summary>
        /// <param name="checkCode">验证字符</param>
        private void CreateImages(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);
            //定义颜色
            Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };
            //定义字体
            string[] font = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" };
            Random rand = new Random();
            //随机输出噪点
            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);
            }

            //输出不同字体和颜色的验证码字符
            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);
            }
            //画一个边框
            g.DrawRectangle(new Pen(Color.Black, 0), 0, 0, image.Width - 1, image.Height - 1);

            //输出到浏览器
            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>
        /// 生成随机的字母
        /// </summary>
        /// <param name="VcodeNum">生成字母的个数</param>
        /// <returns>string</returns>
        private string RndNum(int VcodeNum)
        {
            string Vchar = "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";
            string[] VcArray = Vchar.Split(',');
            string VNum = ""; //由于字符串很短，就不用StringBuilder了
            int temp = -1; //记录上次随机数值，尽量避免生产几个一样的随机数

            //采用一个简单的算法以保证生成随机数的不同
            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;
        }
    }
}

2.新建项目，引入ValidaterPicture.dll类库。

3.创建PrintImage.aspx页，在页面的load中加入如下代码:

PrintImage.aspx.cs

---

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

namespace WebDemo
{
    public partial class _Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            //创建验证码
            ValidaterPictureClass.DrawImage();
            //保存验证图片对应的验证字符串
            Session ["str"] = ValidaterPictureClass.ImageString;
        }
    }
}

4.在需要使用的页面中加入ImageButton控件，注意图片地址为上面的PrintImage.aspx页地址：

   <asp:ImageButton ID="ImageButton1" ImageUrl="~/PrintImage.aspx" runat="server"  Height="21px" Width="85px" />

 

5.具体验证对照的使用方法，在使用页面的提交按钮中加入：

//获取该验证图片对应的字符串
string s = Session["str"].ToString();
if (TextBox1.Text.Trim().ToLower () == s.ToLower() )//tolower是大写转小写转换函数
{
      Label1.Text = "验证正确";
}