ASP.NET with C#生成验证码的过程

  1 using  System;
  2 using  System.IO;
  3 using  System.Web.UI;
  4 using  System.Drawing;
  5 using  System.Drawing.Imaging;
  6 using  System.Drawing.Drawing2D;
  7
  8 namespace  Web.Common
  9 {
 10      /**/ ///  
 11      ///  validate 的摘要说明。
 12      ///  
 13      public   class  Validate: System.Web.UI.Page
 14      {
 15          private   void  Page_Load( object  sender, EventArgs e)
 16          {
 17              string  strValidateCode  =  ValidateCode( 6 ); // 取得随机字符串，并设置Session值
 18             DrawValidateCode(strValidateCode, 50 , 100 ); // 绘图
 19         }
 20     
 21          // 绘图
 22          private   void  DrawValidateCode( string  strValidateCode, int  intFgNoise, int  intBgNoise)
 23          {
 24              if (strValidateCode  ==   null   ||  strValidateCode.Trim()  ==  String.Empty)
 25              {
 26                  return ;
 27             }
 28              else
 29              {
 30                  // 建立一个位图文件 确立长宽
 31                 Bitmap bmpImage  =   new  Bitmap(( int )Math.Ceiling((strValidateCode.Length  *   12.5 )),  22 );
 32                 Graphics grpGraphics  =  Graphics.FromImage(bmpImage);
 33     
 34                  try
 35                  {
 36                      // 生成随机生成器
 37                     Random rndRandom  =   new  Random();
 38     
 39                      // 清空图片背景色
 40                     grpGraphics.Clear(Color.White);
 41     
 42                      // 画图片的背景噪音线
 43                      for ( int  i = 0 ; i < intBgNoise; i ++ )
 44                      {
 45                          int  int_x1  =  rndRandom.Next(bmpImage.Width);
 46                          int  int_x2  =  rndRandom.Next(bmpImage.Width);
 47                          int  int_y1  =  rndRandom.Next(bmpImage.Height);
 48                          int  int_y2  =  rndRandom.Next(bmpImage.Height);
 49     
 50                         grpGraphics.DrawLine( new  Pen(Color.Silver), int_x1, int_y1, int_x2, int_y2);
 51                     }
 52                      // 把产生的随机数以字体的形式写入画面
 53                     Font font  =   new  Font( " Arial " ,  12 , (FontStyle.Bold  |  FontStyle.Italic));
 54                     LinearGradientBrush brhBrush  =   new  LinearGradientBrush( new  Rectangle( 0 ,  0 , bmpImage.Width, bmpImage.Height), Color.Blue, Color.DarkRed,  1.2f ,  true );
 55                     grpGraphics.DrawString(strValidateCode, font, brhBrush,  2 ,  2 );
 56     
 57                      // 画图片的前景噪音点
 58                      for ( int  i = 0 ; i < intFgNoise; i ++ )
 59                      {
 60                          int  int_x  =  rndRandom.Next(bmpImage.Width);
 61                          int  int_y  =  rndRandom.Next(bmpImage.Height);
 62     
 63                         bmpImage.SetPixel(int_x, int_y, Color.FromArgb(rndRandom.Next()));
 64                     }
 65     
 66                      // 画图片的边框线
 67                     grpGraphics.DrawRectangle( new  Pen(Color.Silver),  0 ,  0 , bmpImage.Width  -   1 , bmpImage.Height  -   1 );
 68     
 69                     MemoryStream memsMemoryStream  =   new  MemoryStream();
 70                     bmpImage.Save(memsMemoryStream, ImageFormat.Gif);
 71                     Response.ClearContent();
 72                     Response.ContentType  =   " image/Gif " ;
 73                     Response.BinaryWrite(memsMemoryStream.ToArray());
 74                 }
 75                  finally
 76                  {
 77                     grpGraphics.Dispose();
 78                     bmpImage.Dispose();
 79                 }
 80             }
 81         }
 82     
 83          // 取得随机字符串，并设置Session值
 84          private   string  ValidateCode( int  intLength)
 85          {
 86              int  intNumber;
 87              char  chrCode;
 88              string  strValidateCode  =  String.Empty;
 89     
 90             Random rndRandom  =   new  Random();
 91     
 92              for ( int  i = 0 ;i < intLength;i ++ )
 93              {
 94                 intNumber  =  rndRandom.Next();
 95                  if (intNumber  %   2   ==   0 )
 96                  {
 97                     chrCode  =  ( char )( ' 0 '   +  ( char )(intNumber  %   10 )); // 如果随机数是偶数 取余
 98                 }
 99                  else
100                  {
101                     chrCode  =  ( char )( ' A '   +  ( char )(intNumber  %   26 )); // 如果随机数是奇数 选择从[A-Z]
102                 }
103                 strValidateCode  +=  chrCode.ToString(); 
104             }
105     
106             Session[ " ValidateCode " ]  =  strValidateCode; // 设置Session["ValidateCode"]
107              // Response.Cookies.Add(new HttpCookie("strValidateCode",strValidateCode));
108     
109              return  strValidateCode;
110         }
111
112          Web 窗体设计器生成的代码 #region  Web 窗体设计器生成的代码
113          override   protected   void  OnInit(EventArgs e)
114          {
115              //
116              //  CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
117              //
118             InitializeComponent();
119              base .OnInit(e);
120         }
121         
122          /**/ ///  
123          ///  设计器支持所需的方法 - 不要使用代码编辑器修改
124          ///  此方法的内容。
125          ///  
126          private   void  InitializeComponent()
127          {    
128              this .Load  +=   new  System.EventHandler( this .Page_Load);
129
130         }
131          #endregion
132     }
133
134 }
135