真爱无限的知识驿站

//第一种

using System;
using System.Collections.Generic;
using System.Web;
using System.Drawing;
using System.Drawing.Imaging;
using System.Web.SessionState;

namespace sizhengwang.BLL
{
   /// <summary>
   /// GetValImage 的摘要说明
   /// </summary>
   public class GetValImage : IHttpHandler, IRequiresSessionState
   {

       public void ProcessRequest(HttpContext context)
       {
           context.Response.ContentType = "image/jpeg";
           using (Bitmap bitmap = new Bitmap(80, 20))//创建图片
           {
               using (Graphics gr = Graphics.FromImage(bitmap))//创建图片的画布
               {
                   Random rand = new Random();
                   string code = yzm(4);
                   gr.Clear(Color.White);
                   gr.DrawString(" " + code, new Font("宋体", 14), Brushes.Blue, new PointF(0, 0));

                   bitmap.Save(context.Response.OutputStream, ImageFormat.Jpeg); //返回一个jpeg图片对象
                   HttpContext.Current.Session["code"] = code.ToLower(); //保存到session
               }
           }
       }

       public bool IsReusable
       {
           get
           {
               return false;
           }
       }
       public static string yzm(int len)
       {
           string str = "0,1,2,3,4,5,6,7,8,9,";
           str += "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,";
           str += "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[] s = str.Split(new char[] { ',' });
           string strnum = "";
           int tag = -1;
           Random rnd = new Random();
           
           for (int i = 1; i <= len; i++)
           {
               if (tag == -1)
               {
                   rnd = new Random(i * tag * unchecked((int)DateTime.Now.Ticks));
               }
               int rndnum = rnd.Next(61);
               //if (tag != -1 && tag == rndnum)
               //{
               //   return yzm(1);
               //}
               tag = rndnum;
               strnum += s[rndnum];
           }
           return strnum;
       }
   }
   
}

//第二种

<%@ WebHandler Language="C#" Class="ValidateCode" %>

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

public class ValidateCode : IHttpHandler, IRequiresSessionState
{
   HttpContext context;
    
   //在此文件被访问时自动调用 相当于页面的PageLoad事件
   public void ProcessRequest (HttpContext context1) {
       this.context = context1;
       CreateCheckCodeImage(GenerateCheckCode());
   }

   #region 生成随机字符串
   /// <summary>
   /// 生成随机字符串
   /// </summary>
   /// <returns></returns>
   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)('0' + (char)(number % 10));
           //code = (char)('A' + (char)(number % 26));

           checkCode += code.ToString();
       }

       //Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));
       //当生成好随机字符串后，将它保存在Session
       context.Session["vCode"] = checkCode;//.Add("vCode", checkCode);
       return checkCode;
   }
   #endregion

   /// <summary>
   /// 根据字符串生成图片
   /// </summary>
   /// <param name="checkCode">字符串</param>
   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
           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);

           //准备缓存流
           System.IO.MemoryStream ms = new System.IO.MemoryStream();
           //将图片流存入缓存流
           image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
           //清空相应对象内容
           context.Response.ClearContent();
           //设置相应对象内容格式为图片
           context.Response.ContentType = "image/Gif";
           //将缓存流中的图片流返回客户端
           context.Response.BinaryWrite(ms.ToArray());
       }
       finally
       {
           g.Dispose();//销毁画板
           image.Dispose();//销毁图片
       }
   }
   
   public bool IsReusable {
       get {
           return false;
       }
   }

}