asp.net的验证码控件(收藏) 作者:杲頔

作者:杲頔 文章地址

using System;
using System.Collections.Generic;
using System.Text;

using System.Web;
using System.Drawing;
using System.IO;
using System.Web.SessionState;

namespace jdTools.Web
{
    public class VerifyImageHttpHandle : IHttpHandler, IRequiresSessionState
    {
        private string GetRandomNumberString(int codeCount)
        {
            int j1;
            string strChoice = "2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,U,V,W,X,Y,Z";
            string[] strResult = strChoice.Split(new Char[] { ',' });
            string strReturn = "";
            Random rnd = new Random(unchecked((int)DateTime.Now.Ticks));
            for (int i = 0; i < codeCount; i++)
            {
                Random rnd1 = new Random(rnd.Next() * unchecked((int)DateTime.Now.Ticks));
                j1 = rnd1.Next(strResult.Length);
                rnd = new Random(rnd.Next() * unchecked((int)DateTime.Now.Ticks));
                strReturn = strReturn + strResult[j1].ToString();
            }
            return strReturn;  
        }
        private Color GetColor()
        {
            return Color.Black;
        }
        private Bitmap CreateImage(string str_ValidateCode)
        {
            Random newRandom = new Random((int)DateTime.Now.Ticks);
            int int_ImageWidth = str_ValidateCode.Length * 14;
            int int_ImageHeight = 20;
            //  图高20px
            Bitmap theBitmap = new Bitmap(int_ImageWidth, int_ImageHeight);
            Graphics theGraphics = Graphics.FromImage(theBitmap);
            //  白色背景
            theGraphics.Clear(Color.White);
            //  灰色边框
            theGraphics.DrawRectangle(new Pen(Color.LightGray, 1), 0, 0, int_ImageWidth - 1, int_ImageHeight);

            int num = theBitmap.Width * theBitmap.Height * 30 / 100;
            for (int iCount = 0; iCount < num; iCount++)
            {
                // 在随机的位置使用随机的颜色设置图片的像素
                int x = newRandom.Next(theBitmap.Width);
                int y = newRandom.Next(theBitmap.Height);
                int r = newRandom.Next(255);
                int g = newRandom.Next(255);
                int b = newRandom.Next(255);
                Color c = Color.FromArgb(r, g, b);
                theBitmap.SetPixel(x, y, c);
            }//for


            //  10pt的字体
            Font theFont = new Font("Arial", 12, FontStyle.Bold);

            for (int int_index = 0; int_index < str_ValidateCode.Length; int_index++)
            {
                string str_char = str_ValidateCode.Substring(int_index, 1);
                Brush newBrush = new SolidBrush(GetColor());
                Point thePos = new Point(int_index * 13 + 1 + newRandom.Next(3), 1 + newRandom.Next(3));
                theGraphics.DrawString(str_char, theFont, newBrush, thePos);
            }
            
            theGraphics.Dispose();
            return theBitmap;
            
        }

        IHttpHandler 成员#region IHttpHandler 成员

        public bool IsReusable
        {
            get { return true; }
        }
        public void ProcessRequest(HttpContext context)
        {
            HttpResponse Response = context.Response;
            //  将生成的图片发回客户端
            MemoryStream ms = new MemoryStream();
            string NumStr=GetRandomNumberString(5);
            context.Session.Add("Verify", NumStr);

            Bitmap theBitmap = CreateImage(NumStr);
            theBitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
            Response.ClearContent(); //需要输出图象信息 要修改HTTP头 
            Response.ContentType = "image/jpeg";
            Response.BinaryWrite(ms.ToArray());
            theBitmap.Dispose();
            ms.Close();
            ms.Dispose();
            Response.End();
        }
        #endregion
    }
}

GetRandomNumberString方法用于生成指定个数的随机数字符串。
IHttpHandle接口的ProcessRequest方法可以启用 HTTP Web 请求的处理。
类VerifyImageHttpHandle 继承了IHttpHandle接口用于自定义程序处理的Web请求。然后在web.config的<system.web>节中配置

      <httpHandlers>
        <add verb="*" path="VerifyImg.jd" type="jdTools.Web.VerifyImageHttpHandle"/>
      </httpHandlers>

此时在浏览器中访问VerifyImg.jd时就会得到一个验证码图片，生成验证码的内容就完成了。

现在我们要自定义一个WEB自定义控件。其代码如下：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;


namespace jdTools.Web.UI
{
    [ToolboxData("<{0}:VerifyImage runat=server></{0}:VerifyImage>")]
    public class VerifyImage : WebControl
    {
        public string Value
        {
            get { return HttpContext.Current.Session["Verify"].ToString(); }
        }
        public virtual ImageAlign ImageAlign
        {
            get
            {
                object obj2 = this.ViewState["ImageAlign"];
                if (obj2 != null)
                {
                    return (ImageAlign)obj2;
                }
                return ImageAlign.NotSet;
            }
            set
            {
                if ((value < ImageAlign.NotSet) || (value > ImageAlign.TextTop))
                {
                    throw new ArgumentOutOfRangeException("value");
                }
                this.ViewState["ImageAlign"] = value;
            }

        }

        public VerifyImage()
            : base(HtmlTextWriterTag.Img)
        { }
        protected override void AddAttributesToRender(HtmlTextWriter writer)
        {
            base.AddAttributesToRender(writer);
            writer.AddStyleAttribute(HtmlTextWriterStyle.Cursor, "pointer");
            writer.AddAttribute("onclick", "this.src='VerifyImg.jd?id='+Math.random()", true);
            writer.AddAttribute(HtmlTextWriterAttribute.Src, "VerifyImg.jd");
            string str2;
            switch (this.ImageAlign)
            {
                case ImageAlign.Left:
                    str2 = "left";
                    break;

                case ImageAlign.Right:
                    str2 = "right";
                    break;

                case ImageAlign.Baseline:
                    str2 = "baseline";
                    break;

                case ImageAlign.Top:
                    str2 = "top";
                    break;

                case ImageAlign.Middle:
                    str2 = "middle";
                    break;

                case ImageAlign.Bottom:
                    str2 = "bottom";
                    break;

                case ImageAlign.AbsBottom:
                    str2 = "absbottom";
                    break;

                case ImageAlign.AbsMiddle:
                    str2 = "absmiddle";
                    break;

                case ImageAlign.NotSet:
                    str2="";
                    break;
                default:
                    str2 = "texttop";
                    break;
            }
            if (str2 != "")
                writer.AddAttribute(HtmlTextWriterAttribute.Align, str2);
        }
    }
}

VerifyImage 类定义了两个属性。其中Value属性用于取得session中存放的验证码的值。
这里就很简单了，没有必要详说。

在使用的时候aspx页面如下：

                    <ul>
                        <li>用户名：<asp:TextBox ID="txtUserName" runat="server"></asp:TextBox></li>
                        <li>密　码：<asp:TextBox ID="txtPassWord" runat="server"></asp:TextBox></li>
                        <li>检证码：<asp:TextBox ID="txtVerify" runat="server" Width="50px"></asp:TextBox><jd:VerifyImage ID="verify" runat="server" Height="23px" ImageAlign="AbsMiddle"/></li>
                    </ul>

aspx.cs中：

            if (txtVerify.Text != verify.Value)
            {
                //.验证码错误
            }
            else
            {
                //验证码正确
            }