image2.aspx.cs

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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;

//该源码下载自www.51aspx.com(５１ａｓｐｘ．ｃｏｍ)

using System.Drawing;
using System.Drawing.Drawing2D; //引用的命名控件

namespace ValidationCode
{
    public partial class Image2 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            CreateCheckCodeImage(GetExpressions());
        }

        /// <summary>
        /// 产生算术式
        /// </summary>
        private string GetExpressions()
        {
            Random rd = new Random(); //创建随机数对象       

            int Results = 0;
            int Num1 = rd.Next(10); ;
            int Num2 = rd.Next(10); ;
            string Expressions = "";

            int F = (rd.Next(4) + 1);
            switch (F)
            {
                case 1:
                    Results = Num1 + Num2;
                    Expressions = Num1 + " 加上 " + Num2;// +" 结果是" +Results;
                    break;
                case 2:
                    Results = Num1 - Num2;
                    Expressions = Num1 + " 减去 " + Num2;
                    break;
                case 3:
                    Results = Num1 * Num2;
                    Expressions = Num1 + " 乘以 " + Num2;
                    break;
                case 4:
                    if (Num2 > 0)
                    {
                        Results = Convert.ToInt16(Num1 / Num2);
                        Expressions = Num1 + " 整除 " + Num2;
                    }
                    else
                    {
                        Results = Num1;
                        Expressions = Num1 + " 整除 1";// + Results;
                    }
                    break;
            }

            //验证码值存放到Session中用来比较
            Session["Code"] = Results.ToString();
            return Expressions;

        }

//5_1_a_s_p_x.c_o_m

        /// <summary>
        /// 生成图片（增加背景噪音线、前景噪音点）
        /// </summary>
        /// <param name="checkCode">随机出字符串</param>
        private void CreateCheckCodeImage(string checkCode)
        {
            if (checkCode.Trim() == "" || checkCode == null)
                return;
            System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)(checkCode.Length * 14), 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.White);

                //画图片的背景噪音线
                int i;
                for (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);
                }

                //定义一个含10种字体的数组
                String[] fontFamily ={ "Arial", "Verdana", "Comic Sans MS", "Impact", "Haettenschweiler", "幼圆", "黑体", "隶书", "宋体", "楷体_GB2312" };
                FontStyle[] fontStyle ={ FontStyle.Bold, FontStyle.Italic, FontStyle.Regular, FontStyle.Strikeout, FontStyle.Underline };
                Font font = new System.Drawing.Font(fontFamily[random.Next(9)], 12, fontStyle[random.Next(5)]);
                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
                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.ContentType = "image/Gif";
                Response.BinaryWrite(ms.ToArray());

            }
            catch
            {
                g.Dispose();
                image.Dispose();
            }

        }

    }
}