汉字验证码

闲来无事，就写了一个汉字验证码，不常见吧，废话少说直接上代码：

 protected void Page_Load(object sender, EventArgs e)
    {
        int length = 4;
        string strkey = getString(length);
        byte[] data = CheckCodeService(length, strkey);
        Response.OutputStream.Write(data, 0, data.Length);
    }
    //产生的汉字验证码
    private object[] CreateString(int strLength) { 
      //定义一个数组存储汉字编码的组成元素
        string[] str = new string[16] {"0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f" };
        Random ran = new Random();
        object[] bytes = new object[strLength];
        for (int i = 0; i < strLength; i++) { 
         //获取区位码第一位
            int ran1 = ran.Next(11, 14);
            string str1 = str[ran1].Trim();
            //获取第二位并防止重复
            ran = new Random(ran1*unchecked((int)DateTime.Now.Ticks)+i);
            int ran2;
            if (ran1 == 13)
            {
                ran2 = ran.Next(0, 7);
            }
            else
            {
                ran2 = ran.Next(0, 16);
            }
            string str2 = str[ran2].Trim();
            //获取第三位区位码
            ran = new Random(ran2*unchecked((int)DateTime.Now.Ticks)+i);
            int ran3 = ran.Next(10,16);
            string str3 = str[ran3].Trim();
           //获取第四位区位码
            ran = new Random(ran3 * unchecked((int)DateTime.Now.Ticks)+i);
            int ran4;
            if (ran3 == 10)
            {
                ran4 = ran.Next(1, 16);
            }
            else if (ran3 == 15)
            {
                ran4 = ran.Next(0, 15);
            }
            else

            {
                ran4 = ran.Next(0,16);
            }
            string str4 = str[ran4].Trim();
            //定义字节变量存储产生的随机汉字区位码
            byte byte1 = Convert.ToByte(str1+str2,16);
            byte byte2 = Convert.ToByte(str3+str4,16);
            byte[] stradd = new byte[] {byte1,byte2};
            //将产生的汉字放入数组
            bytes.SetValue(stradd, i);


        }
        return bytes;
    
    
    }

    //获取验证码
    private string getString(int length) {
        Encoding gb = Encoding.GetEncoding("gb2312");
        object[] bytes = CreateString(length);
        //根据汉字字节解码出中文汉字
        string str1 = gb.GetString((byte[])Convert.ChangeType(bytes[0],typeof(byte[])));
        string str2 = gb.GetString((byte[])Convert.ChangeType(bytes[1], typeof(byte[])));
        string str3 = gb.GetString((byte[])Convert.ChangeType(bytes[2], typeof(byte[])));
        string str4 = gb.GetString((byte[])Convert.ChangeType(bytes[3], typeof(byte[])));
        string str = str1 + str2 + str3 + str4;
        Response.Cookies.Add(new HttpCookie("CheckCode",str));
        return str;
    }

    //生成图片验证码
    protected byte[] CheckCodeService(int nLen, string strKey)
    {
        int nBmpWidth = 13 * nLen + 50;
        int nBmpHeight = 25;
        System.Drawing.Bitmap bmp = new System.Drawing.Bitmap(nBmpWidth, nBmpHeight);
        //生成随机背景颜色
        int nRed;
        int nGreen;
        int nBlue;
        //生成三原色
        System.Random rd = new Random((int)System.DateTime.Now.Ticks);
        nRed = rd.Next(255) % 128 + 128;
        nGreen = rd.Next(255) % 128 + 128;
        nBlue = rd.Next(255) % 128 + 128;
        //填充背景
        System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(bmp);
        graph.FillRectangle(new System.Drawing.SolidBrush(System.Drawing.Color.AliceBlue), 0, 0, nBmpWidth, nBmpHeight);
        //绘制干扰线，采用比背景深一些的颜色
        int nLines = 3;
        System.Drawing.Pen pen = new System.Drawing.Pen(System.Drawing.Color.FromArgb(nRed - 17, nGreen - 17, nBlue - 17), 2);
        for (int a = 0; a < nLines; a++)
        {
            int x1 = rd.Next(nBmpWidth);
            int x2 = rd.Next(nBmpHeight);
            int y1 = rd.Next(nBmpWidth);
            int y2 = rd.Next(nBmpHeight);
            graph.DrawLine(pen, x1, y1, x2, y2);

        }
        //画图片的前景噪音点
        for (int i = 0; i < 100; i++)
        {
            int x = rd.Next(bmp.Width);
            int y = rd.Next(bmp.Height);
            bmp.SetPixel(x, y, System.Drawing.Color.FromArgb(rd.Next()));

        }
        //确定字体
        System.Drawing.Font font = new System.Drawing.Font("Courier New", 14 + rd.Next() % 4, System.Drawing.FontStyle.Bold);
        System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new System.Drawing.Rectangle(0, 0, bmp.Width, bmp.Height), System.Drawing.Color.Blue, System.Drawing.Color.DarkRed, 1.2f, true);
        graph.DrawString(strKey, font, brush, 2, 2);
        //输出字节流
        System.IO.MemoryStream stream = new System.IO.MemoryStream();
        bmp.Save(stream, System.Drawing.Imaging.ImageFormat.Jpeg);
        bmp.Dispose();
        graph.Dispose();
        byte[] byteReturn = stream.ToArray();
        stream.Close();
        return byteReturn;
    }