Web/VerificationCode.ashx.cs

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using Seven.Common;
using System.Drawing;
using System.IO;
using System.Drawing.Imaging;
namespace Web
{
    /// <summary>
    /// VerificationCode 的摘要说明
    /// </summary>
    public class VerificationCode : IHttpHandler,System.Web.SessionState.IRequiresSessionState
    {

        public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "text/plain";
            string str_ValidateCode = StringUtils.GetRandString(RandString.All, 4);
            context.Session["imageCode"] = str_ValidateCode;
            int int_ImageWidth = str_ValidateCode.Length * 13;
            Random newRandom = new Random();
            //  图高20px
            Bitmap theBitmap = new Bitmap(int_ImageWidth, 20);
            Graphics theGraphics = Graphics.FromImage(theBitmap);
            //  白色背景
            theGraphics.Clear(Color.White);
            //  灰色边框
            theGraphics.DrawRectangle(new Pen(Color.LightGray, 1), 0, 0, int_ImageWidth - 1, 19);
            //  10pt的字体
            Font theFont = new Font("Arial", 10);
            for (int int_index = 0; int_index < str_ValidateCode.Length; int_index++)
            {
                string str_char = str_ValidateCode.Substring(int_index, 1);
                Brush newBrush = new SolidBrush(GetRandomColor());
                Point thePos = new Point(int_index * 13 + 1 + newRandom.Next(3), 1 + newRandom.Next(3));
                theGraphics.DrawString(str_char, theFont, newBrush, thePos);
            }
            //  将生成的图片发回客户端
           
            context.Response.ContentType = "Image/JPEG";
            theBitmap.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
            theBitmap.Dispose();
            context.ApplicationInstance.CompleteRequest();
            context.Response.OutputStream.Close();
            context.Response.OutputStream.Dispose();
        }

        private Color GetRandomColor()
        {
            Random RandomNum_First = new Random((int)DateTime.Now.Ticks);
            //  对于C#的随机数，没什么好说的
            System.Threading.Thread.Sleep(RandomNum_First.Next(50));
            Random RandomNum_Sencond = new Random((int)DateTime.Now.Ticks);
            //  为了在白色背景上显示，尽量生成深色
            int int_Red = RandomNum_First.Next(256);
            int int_Green = RandomNum_Sencond.Next(256);
            int int_Blue = (int_Red + int_Green > 400) ? 0 : 400 - int_Red - int_Green;
            int_Blue = (int_Blue > 255) ? 255 : int_Blue;