验证码实现

这里贴一段验证码的代码，只做记录，方便直接使用。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;
using System.IO;
using System.Drawing.Imaging;

namespace Elink.Web.Authencation.CheckCode
{
    public partial class SafeCode : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            string chkCode = string.Empty;
            //颜色列表，用于验证码、噪线、噪点 
            Color[] color = new Color[] { Color.Black, Color.Red, Color.Blue, Color.Green, Color.Orange, Color.Brown, Color.Brown, Color.DarkBlue };
            //字体列表，用于验证码 
            string[] font = new string[] { "Times New Roman", "MS Mincho", "Book Antiqua", "Gungsuh", "PMingLiU", "Impact" };
            //验证码的字符集，去掉了一些容易混淆的字符 
            char[] character = { '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'R', 'S', 'T', 'W', 'X', 'Y' };

            Random rnd = new Random();

            //生成验证码字符串 
            for (int i = 0; i < 4; i++)
            {
                chkCode += character[rnd.Next(character.Length)];
            }
            Session["CheckCode"] = chkCode;

            Bitmap bmp = new Bitmap(100, 20);
            Graphics g = Graphics.FromImage(bmp);
            g.Clear(Color.White);

            //画噪线 
            for (int i = 0; i < 5; i++)
            {
                int x1 = rnd.Next(100);
                int y1 = rnd.Next(20);
                int x2 = rnd.Next(100);
                int y2 = rnd.Next(20);
                Color clr = color[rnd.Next(color.Length)];
                g.DrawLine(new Pen(clr), x1, y1, x2, y2);
            }

            //画验证码字符串 
            for (int i = 0; i < chkCode.Length; i++)
            {
                string f = font[rnd.Next(font.Length)];
                Font ft = new Font(f, 12);

                Color clr = color[rnd.Next(color.Length)];
                g.DrawString(chkCode[i].ToString(), ft, new SolidBrush(clr), i * 20 + 8, 4);
            }

            //画噪点 
            for (int i = 0; i < 40; i++)
            {
                int x = rnd.Next(bmp.Width);
                int y = rnd.Next(bmp.Height);
                Color clr = color[rnd.Next(color.Length)];
                bmp.SetPixel(x, y, clr);
            }
            //清除该页输出缓存，设置该页无缓存 
            Response.Buffer = true;
            Response.ExpiresAbsolute = DateTime.Now.AddMilliseconds(0);
            Response.Expires = 0;
            Response.CacheControl = "no-cache";
            Response.AddHeader("Pragma", "No-Cache");

            //将验证码图片写入内存流，并将其以 "image/Png" 格式输出 
            MemoryStream ms = new MemoryStream();

            try
            {
                bmp.Save(ms, ImageFormat.Png);
                Response.ClearContent();
                Response.ContentType = "image/Png";
                Response.BinaryWrite(ms.ToArray());
                Response.End();
            }
            finally
            {
                ////显式释放资源 
                bmp.Dispose();
                g.Dispose();
            }

        }
    }
}

获取session保存的验证码内容

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using NAIS.Common;
using Elink.Common;
using System.Web.Script.Serialization;
using System.Web.SessionState;

namespace Elink.Web.RelationService
{
    /// <summary>
    /// LoginGetCheckCodeValue 的摘要说明
    /// </summary>
    public class LoginGetCheckCodeValue : IHttpHandler, IRequiresSessionState
    {

        public void ProcessRequest(HttpContext context)
        {
            //控件ID
            string returnFlag = context.Request["returnFlag"];
            try
            {
                string reValue = string.Empty;
                if (returnFlag.ToUpper() == "CHECKCODE")
                {
                    reValue = SessionUtils.GetSessionValue(context.Session["CheckCode"]);
                }
                JavaScriptSerializer jsSerializer = new JavaScriptSerializer();
                string json = jsSerializer.Serialize(new { result = true, Data = reValue });
                context.Response.ContentType = "text/plain";
                context.Response.Write(json);
            }
            catch (Exception ex)
            {
                LogUtil.Logger.Error(string.Format("用户登录一般处理程序LoginGetCheckCodeValue：ProcessRequest获取指定返回值异常，指定返回值为={0}", returnFlag), ex);
            }
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}