那些琐碎的知识-----登录验证码

1、新建文件CheckCode.aspx

前台不用写，后台代码为：

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;

public partial class common_CheckCode : System.Web.UI.Page

{

    private void Page_Load(object sender, System.EventArgs e)

    {

        this.CreateCheckCodeImage(GenerateCheckCode());

    }
private string GenerateCheckCode()

    {

        int number;

        char code;

        string checkCode = String.Empty;
System.Random random = new Random();
for (int i = 0; i < 4; i++)

        {

            number = random.Next();
//if (number % 2 == 0)

                code = (char)(‘0‘ + (char)(number % 10));

            //else

                //code = (char)(‘A‘ + (char)(number % 26));
checkCode += code.ToString();

        }
Session["CheckCode"] = checkCode;
return checkCode;

    }
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.AliceBlue);

            g.Clear(Color.FromArgb(246, 251, 255));
//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.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);
System.IO.MemoryStream ms = new System.IO.MemoryStream();

            image.Save(ms, System.Drawing.Imaging.ImageFormat.Bmp);

            Response.ClearContent();

            Response.ContentType = "image/bmp";

            Response.BinaryWrite(ms.ToArray());

        }

        finally

        {

            g.Dispose();

            image.Dispose();

        }

    }

}

2、在需要验证码的页面建立标签

<img id="codeImg" alt="点击更换验证码" style="display: inline; cursor: pointer;" src="CheckCode.aspx" />

3、在需要验证码的页面上引入jquery的js文件，然后添加如下jQuery代码

$(function(){

    $("#codeImg").click(function(){

        $("#codeImg").attr("src","CheckCode.aspx?temp="+(new Date().getTime().toString(36)));

    });

});

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