生成验证码

生成验证码的类：

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.Drawing.Drawing2D;

public partial class yanzheng : 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>
    public string GenerateCheckCode()
    {
        //int number;
        //string strCode = string.Empty;
        随机数种子
        //Random radom = new Random();
        //for (int i = 0; i < 4; i++)
        //{
        //    //随机的整数
        //    number = radom.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Cookie中保存校验码或Session中
        //Session["CheckCode"] = strCode;
        //Response.Cookies.Add(new HttpCookie("CheckCode", strCode));
        //return strCode;

 

        string allChar = "2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,J,K,M,N,P,Q,R,S,T,U,W,X,Y,Z,a,b,c,d,e,f,g,h,j,k,m,n,p,q,r,s,t,u,v,w,x,y,z";
        string[] allCharArray = allChar.Split(',');
        string randomCode = "";
        int temp = -1;

        Random rand = new Random();
        for (int i = 0; i < 4; i++)
        {
            if (temp != -1)
            {
                rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
            }
            int t = rand.Next(53);
            if (temp == t)
            {
                return GenerateCheckCode();
            }
            temp = t;
            randomCode += allCharArray[t];
        }
        Session["CheckCode"] = randomCode;
        return randomCode;
    }
    /// <summary> /// 根据校验码输出图片
    /// </summary> ///
    /// <param name="checkCode">产生的随机校验码</param>
    public 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((int)Math.Ceiling(decimal.Parse((checkCode.Length * 15) + "")), 20);
        //创建ＧＲＡＰＨＩＣＳ对象
        System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(image);
        try
        {
            //生成随机数种子
            Random random = new Random();
            //清空图片背景色
            g.Clear(System.Drawing.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 System.Drawing.Pen(System.Drawing.Color.Silver), x1, y1, x2, y2);
            }
            //输出图片中校验码的字体：１２号Arial,粗斜体
            System.Drawing.Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
            //线形渐变画刷
            System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new System.Drawing.Rectangle(0, 0, image.Width, image.Height), System.Drawing.Color.Blue, System.Drawing.Color.Purple, 1.2f, true);
            g.DrawString(checkCode, font, brush, 2, 3);
            //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, System.Drawing.Color.FromArgb(random.Next()));
            }
            //画图片的边框线
            g.DrawRectangle(new System.Drawing.Pen(System.Drawing.Color.SaddleBrown), 0, 0, image.Width - 1, image.Height - 1);
            //创建内存流用于输出图片
            using (System.IO.MemoryStream ms = new System.IO.MemoryStream())
            {
                //图片格式指定为ＰＮＧ
                image.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
                //清除缓冲区流中的所有输出
                Response.ClearContent();
                //输出流的ＨＴＴＰＭＩＭＥ类型设置为＂image/Png＂
                Response.ContentType = "image/Png";
                //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();
        }
    }

 
}

前端代码：

<input id="TextBox2" name="TextBox2" type="text" size="7" />

 <img src="yanzheng.aspx" id="image1" runat="server" οnclick="show()" style="cursor:pointer" alt="看不清，再来一张"/>

 

 function show()
{ var i=document.getElementById("image1");
i.src="yanzheng.aspx?"+new Date();
//注意这里的new Date一定要加上，否则只会生成一次验证码
}

 

验证输入是否正确：

 

    //判断验证码输入是否正确(不区分大小写)
    public static bool check(string input, string yanzheng)
    {
        bool flag = true;
        if (input.Length != yanzheng.Length)
        {
            flag = false;
        }
        else
        {
            for (int i = 0; i < yanzheng.Length; i++)
            {
                if (yanzheng[i].ToString() != input[i].ToString() && yanzheng[i].ToString().ToLower() != input[i].ToString() && yanzheng[i].ToString().ToUpper() != input[i].ToString())
                {
                    flag = false;
                    break;

                }
            }
        }
        return flag;
    }
}