生成Image的类：

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Drawing;using System.Drawing.Drawing2D;using System.Drawing.Imaging;using System.Security.Cryptography;namespace WebAppToBuildImage{    /// 
    /// 验证码图片类    /// 
    public class VerifyImageEntity    {        /// 
        /// 要显示的文字        /// 
        public string Text        {            get { return this.text; }        }        /// 
        /// 图片        /// 
        public Bitmap Image        {            get { return this.image; }        }        /// 
        /// 宽度        /// 
        public int Width        {            get { return this.width; }        }        /// 
        /// 高度        /// 
        public int Height        {            get { return this.height; }        }        private string text;        private int width;        private int height;        private Bitmap image;        private static byte[] randb = new byte[4];        private static RNGCryptoServiceProvider rand = new RNGCryptoServiceProvider();        /// 
        /// 构造函数        /// 
        /// 要显示的验证码        /// 宽度        /// 高度        public VerifyImageEntity(string code, int width, int height)        {            this.text = code;            this.width = width;            this.height = height;            this.GenerateImage();        }        /// 
        /// 析构函数        /// 
        ~VerifyImageEntity()        {            Dispose(false);        }        public void Dispose()        {            GC.SuppressFinalize(this);            this.Dispose(true);        }        protected virtual void Dispose(bool disposing)        {            if (disposing)                this.image.Dispose();        }        private FontFamily[] fonts = {                                new FontFamily("Times New Roman"),                                new FontFamily("Georgia"),                                new FontFamily("Arial"),                                new FontFamily("Comic Sans MS")                            };        public static int Next()        {            rand.GetBytes(randb);            int value = BitConverter.ToInt32(randb, 0);            if (value < 0) value = -value;            return value;        }        public static int Next(int max)        {            rand.GetBytes(randb);            int value = BitConverter.ToInt32(randb, 0);            value = value % (max + 1);            if (value < 0) value = -value;            return value;        }        public static int Next(int min, int max)        {            int value = Next(max - min) + min;            return value;        }        /// 
        /// 生成验证码图片        /// 
        private void GenerateImage()        {            Bitmap bitmap = new Bitmap(this.width, this.height, PixelFormat.Format32bppArgb);            Graphics g = Graphics.FromImage(bitmap);            Rectangle rect = new Rectangle(0, 0, this.width, this.height);            g.SmoothingMode = SmoothingMode.AntiAlias;            g.Clear(Color.White);            int emSize = Next(3) + 18;//(int)((this.width - 20) * 2 / text.Length);            FontFamily family = fonts[Next(fonts.Length - 1)];            Font font = new Font(family, emSize, FontStyle.Bold);            SizeF measured = new SizeF(0, 0);            SizeF workingSize = new SizeF(this.width, this.height);            while (emSize > 2 && (measured = g.MeasureString(text, font)).Width > workingSize.Width || measured.Height > workingSize.Height)            {                font.Dispose();                font = new Font(family, emSize -= 2);            }            SolidBrush drawBrush = new SolidBrush(Color.FromArgb(Next(100), Next(100), Next(100)));            for (int x = 0; x < 3; x++)            {                Pen linePen = new Pen(Color.FromArgb(Next(150), Next(150), Next(150)), 1);                g.DrawLine(linePen, new PointF(0.0F + Next(20), 0.0F + Next(this.height)), new PointF(0.0F + Next(this.width), 0.0F + Next(this.height)));            }            for (int x = 0; x < this.text.Length; x++)            {                drawBrush.Color = Color.FromArgb(Next(150) + 20, Next(150) + 20, Next(150) + 20);                PointF drawPoint = new PointF(0.0F + Next(4) + x * 15, 8.0F + Next(4));                g.DrawString(this.text[x].ToString(), font, drawBrush, drawPoint);            }            double distort = Next(5, 10) * (Next(10) == 1 ? 1 : -1);            using (Bitmap copy = (Bitmap)bitmap.Clone())            {                for (int y = 0; y < height; y++)                {                    for (int x = 0; x < width; x++)                    {                        int newX = (int)(x + (distort * Math.Sin(Math.PI * y / 84.0)));                        int newY = (int)(y + (distort * Math.Cos(Math.PI * x / 54.0)));                        if (newX < 0 || newX >= width) newX = 0;                        if (newY < 0 || newY >= height) newY = 0;                        bitmap.SetPixel(x, y, copy.GetPixel(newX, newY));                    }                }            }            //g.DrawRectangle(new Pen(Color.Silver), 0, 0, bitmap.Width - 1, bitmap.Height - 1);            font.Dispose();            drawBrush.Dispose();            g.Dispose();            this.image = bitmap;        }    }}

添加一个img.aspx页面用于显示image：

<%@ Page Title="主页" Language="C#" AutoEventWireup="true" ContentType="image/jpeg"    CodeBehind="img.aspx.cs" Inherits="WebAppToBuildImage._Default" %>

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using System.Text;namespace WebAppToBuildImage{    public partial class _Default : System.Web.UI.Page    {        protected void Page_Load(object sender, EventArgs e)        {        }        protected override void OnInit(EventArgs e)        {            base.OnInit(e);            string authStr = CreateAuthStr(4);            System.Diagnostics.Debug.WriteLine(authStr);            VerifyImageEntity verifyimg = new VerifyImageEntity(authStr, 100, 35);            System.Drawing.Bitmap image = verifyimg.Image;            System.Web.HttpContext.Current.Response.ContentType = "image/pjpeg";            //Session["AuthStr"] = authStr.ToLower();            image.Save(this.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);        }        /// 
        /// 产生验证码        /// 
        /// 
      
       验证码
              public static string CreateAuthStr(int len)        {            int number;            StringBuilder checkCode = new StringBuilder();            Random random = new Random();            for (int i = 0; i < len; i++)            {                number = random.Next();                if (number % 2 == 0)                {                    checkCode.Append((char)('0' + (char)(number % 10)));                }                else                {                    checkCode.Append((char)('A' + (char)(number % 26)));                }            }            return checkCode.ToString();        }    }}

调用[看高亮那一句]：

<%@ Page Title="关于我们" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true"    CodeBehind="About.aspx.cs" Inherits="WebAppToBuildImage.About" %>
         
          
          
          
      
     
         
      
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