1using System;
  2using System.Data;
  3using System.Configuration;
  4using System.Web;
  5using System.Web.Security;
  6using System.Web.UI;
  7using System.Web.UI.WebControls;
  8using System.Web.UI.WebControls.WebParts;
  9using System.Web.UI.HtmlControls;
 10using System.Drawing;
 11/**//// <summary>
 12/// checkCode 的摘要说明
 13/// </summary>
 14public class checkCode
 15...{
 16    public checkCode()
 17    ...{
 18        //
 19        // TODO: 在此处添加构造函数逻辑
 20        //
 21    }
 22    public static void DrawImage()
 23    ...{
 24        checkCode img = new checkCode();
 25        HttpContext.Current.Session["CheckCode"] = img.RndNum(4);
 26        img.checkCodes(HttpContext.Current.Session["CheckCode"].ToString());
 27    }
 28    /**//// <summary>
 29    /// 生成验证图片
 30    /// </summary>
 31    /// <param name="checkCode">验证字符</param>
 32    private void checkCodes(string checkCode)
 33    ...{
 34        int iwidth = (int)(checkCode.Length * 13);
 35        System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 23);
 36        Graphics g = Graphics.FromImage(image);
 37        g.Clear(Color.White);
 38        //定义颜色
 39        Color[] c = ...{ Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };
 40        //定义字体 
 41        string[] font = ...{ "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" };
 42        Random rand = new Random();
 43        //随机输出噪点
 44        for (int i = 0; i < 50; i++)
 45        ...{
 46            int x = rand.Next(image.Width);
 47            int y = rand.Next(image.Height);
 48            g.DrawRectangle(new Pen(Color.LightGray, 0), x, y, 1, 1);
 49        }
 50
 51        //输出不同字体和颜色的验证码字符
 52        for (int i = 0; i < checkCode.Length; i++)
 53        ...{
 54            int cindex = rand.Next(7);
 55            int findex = rand.Next(5);
 56
 57            Font f = new System.Drawing.Font(font[findex], 10, System.Drawing.FontStyle.Bold);
 58            Brush b = new System.Drawing.SolidBrush(c[cindex]);
 59            int ii = 4;
 60            if ((i + 1) % 2 == 0)
 61            ...{
 62                ii = 2;
 63            }
 64            g.DrawString(checkCode.Substring(i, 1), f, b, 3 + (i * 12), ii);
 65        }
 66        //画一个边框
 67        g.DrawRectangle(new Pen(Color.Black, 0), 0, 0, image.Width - 1, image.Height - 1);
 68
 69        //输出到浏览器
 70        System.IO.MemoryStream ms = new System.IO.MemoryStream();
 71        image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
 72        HttpContext.Current.Response.ClearContent();
 73        //Response.ClearContent();
 74        HttpContext.Current.Response.ContentType = "image/Jpeg";
 75        HttpContext.Current.Response.BinaryWrite(ms.ToArray());
 76        g.Dispose();
 77        image.Dispose();
 78    }
 79
 80    /**//// <summary>
 81    /// 生成随机的字母
 82    /// </summary>
 83    /// <param name="VcodeNum">生成字母的个数</param>
 84    /// <returns>string</returns>
 85    private string RndNum(int VcodeNum)
 86    ...{
 87        string Vchar = "0,1,2,3,4,5,6,7,8,9";
 88        string[] VcArray = Vchar.Split(',');
 89        string VNum = ""; //由于字符串很短，就不用StringBuilder了
 90        int temp = -1; //记录上次随机数值，尽量避免生产几个一样的随机数
 91
 92        //采用一个简单的算法以保证生成随机数的不同
 93        Random rand = new Random();
 94        for (int i = 1; i < VcodeNum + 1; i++)
 95        ...{
 96            if (temp != -1)
 97            ...{
 98                rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks));
 99            }
100            int t = rand.Next(VcArray.Length);
101            if (temp != -1 && temp == t)
102            ...{
103                return RndNum(VcodeNum);
104            }
105            temp = t;
106            VNum += VcArray[t];
107        }
108        return VNum;
109    }
110
111}
112