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.Imaging;

/// <summary>
/// C#生成彩色验证码
/// </summary>
public partial class GetCode : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        //纯数字验证码
        //Session["Code1"] = Number(4);
        //CreateImage(Session["Code1"].ToString());

        //数字+字母验证码
        Session["Code2"] = Str(4);
        CreateImage(Session["Code2"].ToString());

        //纯字母验证码
        //Session["Code3"] = Str_char(4);
        //CreateImage(Session["Code3"].ToString());
    }

    /// <summary>
    /// 生成验证码
    /// </summary>
    /// <param name="checkCode">需转化为图片的字符串</param>
    private void CreateImage(string checkCode)
    {
        int iwidth = (int)(checkCode.Length * 15);
        System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 30);
        Graphics g = Graphics.FromImage(image);
        g.Clear(Color.LightCyan);
        //定义颜色
        Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple, Color.SkyBlue };
        //定义字体
        string[] font = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体", "Comic Sans MS" };
        Random rand = new Random();
        //随机输出噪点
        for (int i = 0; i < 150; i++)
        {
            int x = rand.Next(image.Width);
            int y = rand.Next(image.Height);
            g.DrawPie(new Pen(Color.LightGray, 0), x, y, 6, 6, 1, 1);
        }

        //输出不同字体和颜色的验证码字符
        for (int i = 0; i < checkCode.Length; i++)
        {
            int cindex = rand.Next(7);
            int findex = rand.Next(6);
            Font fs_font = new System.Drawing.Font(font[findex], 14, System.Drawing.FontStyle.Bold);
            Brush b = new System.Drawing.SolidBrush(c[cindex]);
            int ii = 4;
            if ((i + 1) % 2 == 0)
            {
                ii = 2;
            }
            g.DrawString(checkCode.Substring(i, 1), fs_font, b, 3 + (i * 12), ii);
        }

        //画一个边框
        g.DrawRectangle(new Pen(Color.Red, 0), 100, 0, image.Width - 1, image.Height - 1);
        //输出到浏览器
        System.IO.MemoryStream ms = new System.IO.MemoryStream();
        image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
        Response.ClearContent();//Response.ClearContent();
        Response.ContentType = "image/Jpeg";
        Response.BinaryWrite(ms.ToArray());
        g.Dispose();
        image.Dispose();
    }

    /// <summary>
    /// 生成随机数字
    /// </summary>
    /// <param name="length">生成长度</param>
    /// <returns></returns>
    public static string Number(int Length)
    {
        return Number(Length, false);
    }

    /// <summary>
    /// 生成随机数字
    /// </summary>
    /// <param name="Length">生成长度</param>
    /// <param name="Sleep">是否要在生成前将当前线程阻止以避免重复</param>
    /// <returns></returns>
    public static string Number(int Length, bool Sleep)
    {
        if (Sleep)
            System.Threading.Thread.Sleep(3);
        string result = "";
        System.Random random = new Random();
        for (int i = 0; i < Length; i++)
        {
            result += random.Next(10).ToString();
        }
        return result;
    }

    /// <summary>
    /// 生成随机字母与数字
    /// </summary>
    /// <param name="IntStr">生成长度</param>
    /// <returns></returns>
    public static string Str(int Length)
    {
        return Str(Length, false);
    }
    /// <summary>
    /// 生成随机字母与数字
    /// </summary>
    /// <param name="Length">生成长度</param>
    /// <param name="Sleep">是否要在生成前将当前线程阻止以避免重复</param>
    /// <returns></returns>
    public static string Str(int Length, bool Sleep)
    {
        if (Sleep)
            System.Threading.Thread.Sleep(3);
        char[] Pattern = new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };
        string result = "";
        int n = Pattern.Length;
        System.Random random = new Random(~unchecked((int)DateTime.Now.Ticks));
        for (int i = 0; i < Length; i++)
        {
            int rnd = random.Next(0, n);
            result += Pattern[rnd];
        }
        return result;
    }


    /// <summary>
    /// 生成随机纯字母随机数
    /// </summary>
    /// <param name="IntStr">生成长度</param>
    /// <returns></returns>
    public static string Str_char(int Length)
    {
        return Str_char(Length, false);
    }

    /// <summary>
    /// 生成随机纯字母随机数
    /// </summary>
    /// <param name="Length">生成长度</param>
    /// <param name="Sleep">是否要在生成前将当前线程阻止以避免重复</param>
    /// <returns></returns>
    public static string Str_char(int Length, bool Sleep)
    {
        if (Sleep)
            System.Threading.Thread.Sleep(3);
        char[] Pattern = new char[] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };
        string result = "";
        int n = Pattern.Length;
        System.Random random = new Random(~unchecked((int)DateTime.Now.Ticks));
        for (int i = 0; i < Length; i++)
        {
            int rnd = random.Next(0, n);
            result += Pattern[rnd];
        }
        return result;
    }
}