怎么做验证码

Question

谁跟我讲下思路 我就知道第一步随机生成图片  第二步 随机生成数字  第三步  让数字和图片 配合    我就知道这些  

Answer 1

然后把 数字记录在session里
接着把 图片write到前台，
然后在注册的页面里 ，验证码的图片 的 src指定生成图片的页面。
onclick的时候，重新给图片的src赋值  

Answer 2

帮你百度
http://wostyh.javaeye.com/blog/440426http://edu.iecool.com/show/2652.html

Answer 3

public void MakeCheckCode(string checkCodeCookieName, int len)
        {
            //这儿定义你期待产生的随机字母 
            string[] arrLetter = new string[] {  
                                                   "A", "B", "C", "D", "E", "F", "G", "H", "J", "K", "L", "M", "N", "P", "Q", "R",  
                                                   "S", "T", "U", "V", "W", "X", "Y", "Z", "2", "3", "4", "5", "6", "7", "8", "9" 
                                               };
            //随机颜色 
            Color[] arrColor = new Color[] { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Green, Color.Brown, Color.DarkCyan, Color.Blue };
            //随机字体 
            string[] arrFont = new string[] { "Arial", "Verdana" };            Random romTemp = new Random();
            string strCheckCode = "";
            //产生随机字符串 
            for (int i = 1; i <= len; i++)
            {
                strCheckCode = strCheckCode + arrLetter[romTemp.Next(arrLetter.Length)];
            }
            strCheckCode = strCheckCode.ToUpper();
            //将值写入cook 
            HttpCookie cookTemp = new HttpCookie(checkCodeCookieName);
            cookTemp.Values.Add("CheckCode", strCheckCode);
            this.Context.Response.Cookies.Add(cookTemp);
            int intWidth = strCheckCode.Length * 13; //计算图片需要的宽度 
            Bitmap bitmap1 = new Bitmap(intWidth, 0x16);
            //绘图 
            Graphics graphics1 = Graphics.FromImage(bitmap1);
            graphics1.Clear(Color.White);
            for (int i = 0; i < 5; i++)
            {
                //随机字母宽度 
                int intLetterWidth = romTemp.Next(bitmap1.Width);
                //随机字母高度 
                int intLetterHeight = romTemp.Next(bitmap1.Height);
                graphics1.DrawRectangle(new Pen(Color.DarkGray, 0f), intLetterWidth, intLetterHeight, 1, 1);
            }
            for (int i = 0; i < strCheckCode.Length; i++)
            {
                int num7 = romTemp.Next(arrColor.Length);
                int num8 = romTemp.Next(arrFont.Length);
                Font font1 = new Font(arrFont[num8], 10f, FontStyle.Bold);
                Brush brush1 = new SolidBrush(arrColor[num7]);
                graphics1.DrawString(strCheckCode.Substring(i, 1), font1, brush1, (float)(3 + (i * 11)), 3f);
            }
            graphics1.DrawRectangle(new Pen(Color.LightGray, 0f), 0, 0, bitmap1.Width - 1, bitmap1.Height - 1);
            graphics1.Dispose();
            System.IO.MemoryStream stream1 = new System.IO.MemoryStream();
            bitmap1.Save(stream1, System.Drawing.Imaging.ImageFormat.Gif);
            this.Context.Response.ClearContent();
            this.Context.Response.ContentType = "image/Gif";
            this.Context.Response.BinaryWrite(stream1.ToArray());
            bitmap1.Dispose();
            graphics1.Dispose();
        }  

Answer 4

gdi,写数字,加正弦扭曲变形,x轴y轴方向坐标分别位移随机数,基本人看着都费劲了

Answer 5

http://topic.csdn.net/u/20090429/16/9aee7f0f-16cb-4c49-a789-903aa8143932.html

Answer 6

[code=C#]//---------------------------------------------// RandomImage.aspx.cs验证码生成页面后台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;
using System.IO;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;
using System.Drawing.Printing;public partial class RandomImage : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {        CreateCheckCodeImage(GenerateCheckCode());
    }
    /// <summary>
    /// 生成随机校验码字符串
    /// </summary>
    /// <returns>生成的随机校验码字符串</returns>
    private string GenerateCheckCode()
    {
        int number;
        string strCode = string.Empty;        //随机数种子
        Random random = new Random();        for (int i = 0; i < 4; i++) //校验码长度为4
        {
            //随机的整数
            number = random.Next();            //字符从0-9,A-Z中随机产生,对应的ASCII码分别为
            //48-57,65-90
            number = number % 36;
            if (number < 10)
            {
                number += 48;
            }
            else
            {
                number += 55;
            }
            strCode += ((char)number).ToString();
        }        //在session中保存校验码
        Session["CheckCode"] = strCode;
        return strCode;
    }    /// <summary>
    /// 根据校验码输出图片
    /// </summary>
    /// <param name="checkCode">产生的随机校验码</param>
    private void CreateCheckCodeImage(string checkCode)
    {
        //若校验码为空，则直接返回
        if (checkCode == null || checkCode.Trim() == String.Empty)
        {
            return;
        }
        //根据校验码的长度确定输出图片的长度
        System.Drawing.Bitmap image = new System.Drawing.Bitmap(55, 20);//(int)Math.Ceiling(Convert.ToDouble(checkCode.Length * 15))
        //创建Graphics对象
        Graphics g = Graphics.FromImage(image);
        try
        {
            //生成随机数种子
            Random random = new Random();
            //清空图片背景色
            g.Clear(Color.White);
            //画图片的背景噪音线 10条
            //---------------------------------------------------
            for (int i = 0; i < 10; i++)
            {
                //噪音线起点坐标(x1,y1),终点坐标(x2,y2)
                int x1 = random.Next(image.Width);
                int x2 = random.Next(image.Width);
                int y1 = random.Next(image.Height);
                int y2 = random.Next(image.Height);                //用银色画出噪音线
                g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
            }
            //---------------------------------------------------
            //Brush b = Brushes.Silver;
            //g.FillRectangle(b, 0, 0, image.Width, image.Height);
            //---------------------以上两种任选其一------------------------------
            //输出图片中校验码的字体: 12号Arial,粗斜体
            Font font = new Font("Arial",12,(FontStyle.Bold | FontStyle.Italic));            //线性渐变画刷
            LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),Color.Blue,Color.Purple,1.2f,true);
            g.DrawString(checkCode, font, brush, 2, 2);            //画图片的前景噪音点 50个
            for (int i = 0; i < 50; 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.Peru),0,0,image.Width - 1,image.Height - 1);            //创建内存流用于输出图片
            using (MemoryStream ms = new MemoryStream())
            {
                //图片格式指定为png
                image.Save(ms, ImageFormat.Jpeg);
                //清除缓冲区流中的所有输出
                Response.ClearContent();
                //输出流的HTTP MIME类型设置为"image/Png"
                Response.ContentType = "image/Jpeg";
                //输出图片的二进制流
                Response.BinaryWrite(ms.ToArray());
            }
        }
        finally
        {
            //释放Bitmap对象和Graphics对象
            g.Dispose();
            image.Dispose();
        }
    }
}
//--------------------------------------------------------------------//测试页面 dafault.aspx<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" Debug="true" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>无标题页</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <asp:TextBox ID="txtCode" runat="server"></asp:TextBox>
        <asp:Image ID="Image1" runat="server" ImageUrl="~/RandomImage.aspx" />
        <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" /><hr />
        <asp:Label ID="lblMsg" runat="server" Text="Label"></asp:Label>
    </div>
    </form>
</body>
</html>
//----------------------------------------------------//测试页面后台using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        if (string.Compare(Session["CheckCode"].ToString(), this.txtCode.Text, true) != 0)
        {
            lblMsg.Text = "验证码错误，请输入正确的验证码。";
            return;
        }
        else
        {
            lblMsg.Text = "成功";
        }
    }
}

Answer 7

private void CreateCheckCodeImage(string checkCode) 参数错了吧

Answer 8

http://www.cnblogs.com/ired/archive/2008/06/11/1217544.html

Answer 9

http://www.zlblogs.com/verify-code.html
用户登录验证码怎么做?
请看这里，有例子下载。