网上有很多关于验证码做法的资料,但是真正做得完整的却非常少,所以昨天晚上参考了作者：CSDN 上kwklover 的在ASP.NET下实现数字和字符相混合的验证码 (混合,完整,遗憾的是vb.net,说到这里我想我得感谢stone(QQ9337874),因为我在把VB译成C#的过程中几番出错,最终这段翻译由他完成)!!

随机汉字参考了http://navicy.cnblogs.com/archive/2005/05/08/150756.html这篇文章的,

而最终的纯数字以及GDI+绘图则是从□☆近三十☆(QQ19302038)传给我的一个OA案例里面分离出来的!

所以完整的说,这里面几乎都是别人做好了的,我只是整理出来了!

完整的下载地址是　http://www.cnblogs.com/Files/thcjp/gdi.rar　

下面把代码的重点部分贴出来，如果看源文件有什么不明白可以问偶　ＱＱ１１０５３５８０８

效果如图(我确实懒了点,按纽的名字都没有改,哈哈)
需要说明的是,因为提交对比后,页面是重新刷新了,所以文本框里面看见的和后面图片显示不一样,这个不需要太多说明吧!!

 混合模式刷新出现约界错误 已经被 stone(QQ9337874) 修正!!

下面是ＧＤＩ＋绘图的代码段，以及显示的调用等
using System;
using System.Data;
using System.Configuration;
using System.Collections;
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.Drawing2D;
using System.Drawing.Imaging;
using System.Drawing.Text;
using System.Drawing;
using System.Text;

public partial class png : System.Web.UI.Page
{
    private readonly string ImagePath = "Validator.jpg";
    private static string gif = "";

    protected void Page_Load(object sender, EventArgs e)
    {

        switch (Request.QueryString["aa"])
        {
            case "1":
                gif = stxt();
                Session["gif"]= stxt();
                break;
            case "2":
                gif = GetRandomint();
                 Session["gif"]= GetRandomint();
                break;
            case "3":
                gif = RndNum(3);
                 Session["gif"]= RndNum(3);
                break;
            default:
                gif = RndNum(3);
                 Session["gif"]= GetRandomint();
                break;
        }
       
        /**////创建Bmp位图
        Bitmap bitMapImage = new System.Drawing.Bitmap(Server.MapPath(ImagePath));
        Graphics graphicImage = Graphics.FromImage(bitMapImage);

        /**////设置画笔的输出模式
        graphicImage.SmoothingMode = SmoothingMode.HighSpeed;
        /**////添加文本字符串
        graphicImage.DrawString(gif, new Font("Arial", 20, FontStyle.Bold), SystemBrushes.WindowText, new Point(0, 0));

        /**////设置图像输出的格式
        Response.ContentType = "image/jpeg";

        /**////保存数据流
        bitMapImage.Save(Response.OutputStream, ImageFormat.Jpeg);

        /**////释放占用的资源
        graphicImage.Dispose();
        bitMapImage.Dispose();
    }
返回纯数字

    private String GetRandomint()
    {
        Random random = new Random();
        return (random.Next(100000, 999999).ToString());
    }

返回文字＼数字＼字母混合的

public static 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,W,X,Y,Z,呵,哈,弹,簧,秤,嬉,戏";
        String[] VcArray = Vchar.Split(',');
        String VNum = "";
        Random random = new Random();
        for (int i = 1; i <= VcodeNum; i++)
        {
            int iNum = 0;
            while ((iNum = Convert.ToInt32(VcArray.Length * random.NextDouble())) ==VcArray.Length )
            {
                iNum = Convert.ToInt32(VcArray.Length * random.NextDouble());
            }
            VNum += VcArray[iNum];
            // VNum += VcArray[Convert.ToInt32(VcArray.Length*random.NextDouble())];
        }
        return VNum;
    }
返回汉字的
       public static object[] CreateRegionCode(int strlength)
        {
            //定义一个字符串数组储存汉字编码的组成元素
            string[] rBase=new String [16]{"0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f"};
            
            Random rnd=new Random();
        
            //定义一个object数组用来
            object[] bytes=new object[strlength];
 
            /**//**//**//*每循环一次产生一个含两个元素的十六进制字节数组，并将其放入bject数组中
             每个汉字有四个区位码组成
             区位码第1位和区位码第2位作为字节数组第一个元素
             区位码第3位和区位码第4位作为字节数组第二个元素
            */
            for(int i=0;i            {
                //区位码第1位
                int r1=rnd.Next(11,14);
                string str_r1=rBase[r1].Trim();
 
                //区位码第2位
                rnd=new Random(r1*unchecked((int)DateTime.Now.Ticks)+i);//更换随机数发生器的种子避免产生重复值
                int r2;
                if (r1==13)
                {
                    r2=rnd.Next(0,7);
                }
                else
                {
                    r2=rnd.Next(0,16);
                }
                string str_r2=rBase[r2].Trim();
 
                //区位码第3位
                rnd=new Random(r2*unchecked((int)DateTime.Now.Ticks)+i);
                int r3=rnd.Next(10,16);
                string str_r3=rBase[r3].Trim();
 
                //区位码第4位
                rnd=new Random(r3*unchecked((int)DateTime.Now.Ticks)+i);
                int r4;
                if (r3==10)
                {
                    r4=rnd.Next(1,16);
                }
                else if (r3==15)
                {
                    r4=rnd.Next(0,15);
                }
                else
                {
                    r4=rnd.Next(0,16);
                }
                string str_r4=rBase[r4].Trim();
 
                //定义两个字节变量存储产生的随机汉字区位码
                byte byte1=Convert.ToByte(str_r1 + str_r2,16);
                byte byte2=Convert.ToByte(str_r3 + str_r4,16);
                //将两个字节变量存储在字节数组中
                byte[] str_r=new byte[]{byte1,byte2};
 
                //将产生的一个汉字的字节数组放入object数组中
                bytes.SetValue(str_r,i);
                
            }
 
            return bytes;
 
            }
    private string stxt()
    {
        Encoding gb = Encoding.GetEncoding("gb2312");

        //调用函数产生4个随机中文汉字编码
        object[] bytes = CreateRegionCode(3);

        //根据汉字编码的字节数组解码出中文汉字
        string str1 = gb.GetString((byte[])Convert.ChangeType(bytes[0], typeof(byte[])));
        string str2 = gb.GetString((byte[])Convert.ChangeType(bytes[1], typeof(byte[])));
        string str3 = gb.GetString((byte[])Convert.ChangeType(bytes[2], typeof(byte[])));

        string txt = str1 + str2 + str3;
        return txt;
    }
我们调用页的代码如下

ＨＴＭＬ代码
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="view.aspx.cs" Inherits="view" %>

http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

http://www.w3.org/1999/xhtml" >