生成验证码

using System;
using System.Collections;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;
using System.Drawing.Drawing2D;


namespace GZPI.Gateway
{
    /// <summary>
    /// GenerateCheckCode 的摘要说明。
    /// </summary>
    public class GenerateCheckCode : System.Web.UI.Page
    {
        private void Page_Load(object sender, System.EventArgs e)
        {
            // 在此处放置用户代码以初始化页面
            this.CreateCheckCodeImage(GenerateCheckCodes(4));
        }

        #region Web 窗体设计器生成的代码
        override protected void OnInit(EventArgs e)
        {
            //
            // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
            //
            InitializeComponent();
            base.OnInit(e);
        }
        
        /// <summary>
        /// 设计器支持所需的方法 - 不要使用代码编辑器修改
        /// 此方法的内容。
        /// </summary>
        private void InitializeComponent()
        {    
            this.Load += new System.EventHandler(this.Page_Load);
        }
        #endregion

        private string GenerateCheckCodes(int iCount)
        {
            int number;
            string checkCode = String.Empty;
            int iSeed = DateTime.Now.Millisecond;
            System.Random random = new Random(iSeed);
            for (int i = 0; i < iCount; i++)
            {
                number = random.Next(10);
                checkCode += number.ToString();
            }

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



        private void CreateCheckCodeImage(string checkCode)
        {
            if (checkCode == null || checkCode.Trim() == String.Empty)
                return;
            int iWordWidth = 15;
            int iImageWidth = checkCode.Length * iWordWidth;
            Bitmap image = new Bitmap(iImageWidth, 20);
            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);

                //画图片的背景噪音点
                for (int i = 0; i < 20; 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);
                }

                //画图片的背景噪音线 
                for (int i = 0; i < 2; i++)
                {
                    int x1 = 0;
                    int x2 = image.Width;
                    int y1 = random.Next(image.Height);
                    int y2 = random.Next(image.Height);
                    if (i == 0)
                    {
                        g.DrawLine(new Pen(Color.Gray, 2), x1, y1, x2, y2);
                    }
            
                }


                for (int i = 0; i < checkCode.Length; i++)
                {

                    string Code = checkCode[i].ToString();
                    int xLeft = iWordWidth * (i);
                    random = new Random(xLeft);
                    int iSeed = DateTime.Now.Millisecond;
                    int iValue = random.Next(iSeed) % 4;
                    if (iValue == 0)
                    {
                        Font font = new Font("Arial", 13, (FontStyle.Bold | System.Drawing.FontStyle.Italic));
                        Rectangle rc = new Rectangle(xLeft, 0, iWordWidth, image.Height);
                        LinearGradientBrush brush = new LinearGradientBrush(rc, Color.Blue, Color.Red, 1.5f, true);
                        g.DrawString(Code, font, brush, xLeft, 2);
                    }
                    else if (iValue == 1)
                    {
                        Font font = new System.Drawing.Font("楷体", 13, (FontStyle.Bold));
                        Rectangle rc = new Rectangle(xLeft, 0, iWordWidth, image.Height);
                        LinearGradientBrush brush = new LinearGradientBrush(rc, Color.Blue, Color.DarkRed, 1.3f, true);
                        g.DrawString(Code, font, brush, xLeft, 2);
                    }
                    else if (iValue == 2)
                    {
                        Font font = new System.Drawing.Font("宋体", 13, (System.Drawing.FontStyle.Bold));
                        Rectangle rc = new Rectangle(xLeft, 0, iWordWidth, image.Height);
                        LinearGradientBrush brush = new LinearGradientBrush(rc, Color.Green, Color.Blue, 1.2f, true);
                        g.DrawString(Code, font, brush, xLeft, 2);
                    }
                    else if (iValue == 3)
                    {
                        Font font = new System.Drawing.Font("黑体", 13, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Bold));
                        Rectangle rc = new Rectangle(xLeft, 0, iWordWidth, image.Height);
                        LinearGradientBrush brush = new LinearGradientBrush(rc, Color.Blue, Color.Green, 1.8f, true);
                        g.DrawString(Code, font, brush, xLeft, 2);
                    }
                }
                //////画图片的前景噪音点 
                //for (int i = 0; i < 8; 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.Gif);
                Response.ClearContent();

                Response.BinaryWrite(ms.ToArray());
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }
    }
}

 

　　四、效果图展示
　　验证码数字

　　验证码数字+字母

　　验证码汉字

 

转载自：   http://www.cnblogs.com/dreamof/archive/2009/01/22/1379822.html