C#验证码

using  System;

using  System.Drawing;

using  System.Drawing.Drawing2D;

using  System.Drawing.Imaging;

using  System.IO;

using  System.Text;

using  System.Web;

namespace  Demo

{

     /// <summary>

     /// Captcha

     /// </summary>

     public  class  Captcha

     {

         #region Private Field

         /// <summary>

         /// 随机种子

         /// </summary>

         private  Random objRandom =  new  Random();

         #endregion

         #region Public Property

         #region 验证码长度

         /// <summary>

         /// 验证码长度

         /// </summary>

         private  int  length = 4;

         /// <summary>

         /// 验证码长度(默认为4)

         /// </summary>

         public  int  Length

         {

             get  {  return  this .length; }

             set  {  this .length = value; }

         }

         #endregion

         #region 验证码字符串

         /// <summary>

         /// 验证码字符串

         /// </summary>

         private  string  verifyCodeText =  null ;

         /// <summary>

         /// 验证码字符串

         /// </summary>

         public  string  VerifyCodeText

         {

             get  {  return  this .verifyCodeText; }

             set  {  this .verifyCodeText = value; }

         }

         #endregion

         #region 是否加入小写字母

         /// <summary>

         /// 是否加入小写字母

         /// </summary>

         private  bool  addLowerLetter =  false ;

         /// <summary>

         /// 是否加入小写字母(不包括o)

         /// </summary>

         public  bool  AddLowerLetter

         {

             get  {  return  this .addLowerLetter; }

             set  {  this .addLowerLetter = value; }

         }

         #endregion

         #region 是否加入大写字母

         /// <summary>

         /// 是否加入大写字母

         /// </summary>

         private  bool  addUpperLetter =  false ;

         /// <summary>

         /// 是否加入大写字母(不包括O)

         /// </summary>

         public  bool  AddUpperLetter

         {

             get  {  return  this .addUpperLetter; }

             set  {  this .addUpperLetter = value; }

         }

         #endregion

         #region 字体大小

         /// <summary>

         /// 字体大小

         /// </summary>

         private  int  fontSize = 18;

         /// <summary>

         /// 字体大小(默认为18)

         /// </summary>

         public  int  FontSize

         {

             get  {  return  this .fontSize; }

             set  {  this .fontSize = value; }

         }

         #endregion

         #region 字体颜色

         /// <summary>

         /// 字体颜色

         /// </summary>

         private  Color fontColor = Color.Blue;

         /// <summary>

         /// 字体颜色(默认为Blue)

         /// </summary>

         public  Color FontColor

         {

             get  {  return  this .fontColor; }

             set  {  this .fontColor = value; }

         }

         #endregion

         #region 字体类型

         /// <summary>

         /// 字体类型

         /// </summary>

         private  string  fontFamily =  "Verdana" ;

         /// <summary>

         /// 字体类型(默认为Verdana)

         /// </summary>

         public  string  FontFamily

         {

             get  {  return  this .fontFamily; }

             set  {  this .fontFamily = value; }

         }

         #endregion

         #region 背景色

         /// <summary>

         /// 背景色

         /// </summary>

         private  Color backgroundColor = Color.AliceBlue;

         /// <summary>

         /// 背景色(默认为AliceBlue)

         /// </summary>

         public  Color BackgroundColor

         {

             get  {  return  this .backgroundColor; }

             set  {  this .backgroundColor = value; }

         }

         #endregion

         #region 前景噪点数量

         /// <summary>

         /// 前景噪点数量

         /// </summary>

         private  int  foreNoisePointCount = 2;

         /// <summary>

         /// 前景噪点数量(默认为2)

         /// </summary>

         public  int  ForeNoisePointCount

         {

             get  {  return  this .foreNoisePointCount; }

             set  {  this .foreNoisePointCount = value; }

         }

         #endregion

         #region 随机码的旋转角度

         /// <summary>

         /// 随机码的旋转角度

         /// </summary>

         private  int  randomAngle = 45;

         /// <summary>

         /// 随机码的旋转角度(默认为40度)

         /// </summary>

         public  int  RandomAngle

         {

             get  {  return  this .randomAngle; }

             set  {  this .randomAngle = value; }

         }

         #endregion

         #endregion

         #region Constructor Method

         /// <summary>

         /// 构造方法

         /// </summary>

         public  Captcha()

         {

             this .GetText();

         }

         #endregion

         #region Private Method

         /// <summary>

         /// 得到验证码字符串

         /// </summary>

         private  void  GetText()

         {

             //没有外部输入验证码时随机生成

             if  (String.IsNullOrEmpty( this .verifyCodeText))

             {

                 StringBuilder objStringBuilder =  new  StringBuilder();

                 //加入数字1-9

                 for  ( int  i = 1; i <= 9; i++)

                 {

                     objStringBuilder.Append(i.ToString());

                 }

                 //加入大写字母A-Z，不包括O

                 if  ( this .addUpperLetter)

                 {

                     char  temp =  ' ' ;

                     for  ( int  i = 0; i < 26; i++)

                     {

                         temp = Convert.ToChar(i + 65);

                         //如果生成的字母不是'O'

                         if  (!temp.Equals( 'O' ))

                         {

                             objStringBuilder.Append(temp);

                         }

                     }

                 }

                 //加入小写字母a-z，不包括o

                 if  ( this .addLowerLetter)

                 {

                     char  temp =  ' ' ;

                     for  ( int  i = 0; i < 26; i++)

                     {

                         temp = Convert.ToChar(i + 97);

                         //如果生成的字母不是'o'

                         if  (!temp.Equals( 'o' ))

                         {

                             objStringBuilder.Append(temp);

                         }

                     }

                 }

                 //生成验证码字符串

                 {

                     int  index = 0;

                     for  ( int  i = 0; i < length; i++)

                     {

                         index = objRandom.Next(0, objStringBuilder.Length);

                         this .verifyCodeText += objStringBuilder[index];

                         objStringBuilder.Remove(index, 1);

                     }

                 }

             }

         }

         /// <summary>

         /// 得到验证码图片

         /// </summary>

         private  Bitmap GetImage()

         {

             Bitmap result =  null ;

             //创建绘图

             result =  new  Bitmap( this .verifyCodeText.Length * 16, 25);

             using  (Graphics objGraphics = Graphics.FromImage(result))

             {

                 objGraphics.SmoothingMode = SmoothingMode.HighQuality;

                 //清除整个绘图面并以指定背景色填充

                 objGraphics.Clear( this .backgroundColor);

                 //创建画笔

                 using  (SolidBrush objSolidBrush =  new  SolidBrush( this .fontColor))

                 {

                     this .AddForeNoisePoint(result);

                     this .AddBackgroundNoisePoint(result, objGraphics);

                     //文字居中

                     StringFormat objStringFormat =  new  StringFormat(StringFormatFlags.NoClip);

                     objStringFormat.Alignment = StringAlignment.Center;

                     objStringFormat.LineAlignment = StringAlignment.Center;

                     //字体样式

                     Font objFont =  new  Font( this .fontFamily, objRandom.Next( this .fontSize - 3,  this .fontSize), FontStyle.Regular);

                     //验证码旋转，防止机器识别

                     char [] chars =  this .verifyCodeText.ToCharArray();

                     for  ( int  i = 0; i < chars.Length; i++)

                     {

                         //转动的度数

                         float  angle = objRandom.Next(- this .randomAngle,  this .randomAngle);

                         objGraphics.TranslateTransform(12, 12);

                         objGraphics.RotateTransform(angle);

                         objGraphics.DrawString(chars[i].ToString(), objFont, objSolidBrush, -2, 2, objStringFormat);

                         objGraphics.RotateTransform(-angle);

                         objGraphics.TranslateTransform(2, -12);

                     }

                 }

             }

             return  result;

         }

         /// <summary>

         /// 添加前景噪点

         /// </summary>

         /// <param name="objBitmap"></param>

         private  void  AddForeNoisePoint(Bitmap objBitmap)

         {

             for  ( int  i = 0; i < objBitmap.Width *  this .foreNoisePointCount; i++)

             {

                 objBitmap.SetPixel(objRandom.Next(objBitmap.Width), objRandom.Next(objBitmap.Height),  this .fontColor);

             }

         }

         /// <summary>

         /// 添加背景噪点

         /// </summary>

         /// <param name="objBitmap"></param>

         /// <param name="objGraphics"></param>

         private  void  AddBackgroundNoisePoint(Bitmap objBitmap, Graphics objGraphics)

         {

             using  (Pen objPen =  new  Pen(Color.Azure, 0))

             {

                 for  ( int  i = 0; i < objBitmap.Width * 2; i++)

                 {

                     objGraphics.DrawRectangle(objPen, objRandom.Next(objBitmap.Width), objRandom.Next(objBitmap.Height), 1, 1);

                 }

             }

         }

         #endregion

         #region Public Method

         public  void  Output(HttpResponse objHttpResponse)

         {

             using  (Bitmap objBitmap =  this .GetImage())

             {

                 if  (objBitmap !=  null )

                 {

                     using  (MemoryStream objMS =  new  MemoryStream())

                     {

                         objBitmap.Save(objMS, ImageFormat.Jpeg);

                         HttpContext.Current.Response.ClearContent();

                         HttpContext.Current.Response.ContentType =  "image/Jpeg" ;

                         HttpContext.Current.Response.BinaryWrite(objMS.ToArray());

                         HttpContext.Current.Response.Flush();

                         HttpContext.Current.Response.End();

                     }

                 }

             }

         }

         #endregion

     }

}