asp.net中的比较完美的验证码

本文转载：http://blog.csdn.net/zjk20108023/article/details/7836174

要实现如图的效果的验证码，分以下步骤：

第一、布局好调用验证码的登录页面（命名：Login.aspx），注意：验证码位置可以是服务器控件 Image，也可以是html标签写的<img>，但是图片url就是一个页面（命名：ValidateCode.aspx）(将在下面讲述。)比如：<asp:Image ID=“vcImg”      ImageUrl="~/ValidateCode.aspx"   runat="server" />

第二、生成类文件 (命名：validatedCode）

[csharp] view plaincopyprint?
  1. using System; 
  2. using System.Data; 
  3. using System.Configuration; 
  4. using System.Linq; 
  5. using System.Web; 
  6. using System.Web.Security; 
  7. using System.Web.UI; 
  8. using System.Web.UI.HtmlControls; 
  9. using System.Web.UI.WebControls; 
  10. using System.Web.UI.WebControls.WebParts; 
  11. using System.Xml.Linq; 
  12. using System.Drawing; 
  13. using System.IO; 
  14. using System.Drawing.Imaging; 
  15.  
  16. /// <summary> 
  17. /// Summary description for validatedCode 
  18. /// </summary> 
  19. public class validatedCode 
  20. {    
  21.        #region  验证码长度(默认6个验证码的长度) 
  22.         int length = 4; 
  23.         public int Length 
  24.         { 
  25.             get { return length; } 
  26.             set { length = value; } 
  27.         } 
  28.         #endregion 
  30.         #region 验证码字体大小(为了显示扭曲效果，默认40像素，可以自行修改) 
  31.         int fontSize = 40; 
  32.         public int FontSize 
  33.         { 
  34.             get { return fontSize; } 
  35.             set { fontSize = value; } 
  36.         } 
  37.         #endregion 
  39.         #region 边框补(默认1像素) 
  40.         int padding = 2; 
  41.         public int Padding 
  42.         { 
  43.             get { return padding; } 
  44.             set { padding = value; } 
  45.         } 
  46.         #endregion 
  48.         #region 是否输出燥点(默认不输出) 
  49.         bool chaos = true; 
  50.         public bool Chaos 
  51.         { 
  52.             get { return chaos; } 
  53.             set { chaos = value; } 
  54.         } 
  55.         #endregion 
  57.         #region 输出燥点的颜色(默认灰色) 
  58.         Color chaosColor = Color.LightGray; 
  59.         public Color ChaosColor 
  60.         { 
  61.             get { return chaosColor; } 
  62.             set { chaosColor = value; } 
  63.         } 
  64.         #endregion 
  66.         #region 自定义背景色(默认白色) 
  67.         Color backgroundColor = Color.White; 
  68.         public Color BackgroundColor 
  69.         { 
  70.             get { return backgroundColor; } 
  71.             set { backgroundColor = value; } 
  72.         } 
  73.         #endregion 
  75.         #region 自定义随机颜色数组 
  76.         Color[] colors = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple }; 
  77.         public Color[] Colors 
  78.         { 
  79.             get { return colors; } 
  80.             set { colors = value; } 
  81.         } 
  82.         #endregion 
  84.         #region 自定义字体数组 
  85.         string[] fonts = { "Arial", "Georgia" }; 
  86.         public string[] Fonts 
  87.         { 
  88.             get { return fonts; } 
  89.             set { fonts = value; } 
  90.         } 
  91.         #endregion 
  93.         #region 自定义随机码字符串序列(使用逗号分隔) 
  94.         string codeSerial = "0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z"; 
  95.         public string CodeSerial 
  96.         { 
  97.             get { return codeSerial; } 
  98.             set { codeSerial = value; } 
  99.         } 
  100.         #endregion 
  102.         #region 产生波形滤镜效果 
  103.  
  104.         private const double PI = 3.1415926535897932384626433832795; 
  105.         private const double PI2 = 6.283185307179586476925286766559; 
  106.  
  107.         /// <summary> 
  108.         /// 正弦曲线Wave扭曲图片（Edit By 51aspx.com） 
  109.         /// </summary> 
  110.         /// <param name="srcBmp">图片路径</param> 
  111.         /// <param name="bXDir">如果扭曲则选择为True</param> 
  112.         /// <param name="nMultValue">波形的幅度倍数，越大扭曲的程度越高，一般为3</param> 
  113.         /// <param name="dPhase">波形的起始相位，取值区间[0-2*PI)</param> 
  114.         /// <returns></returns> 
  115.         public System.Drawing.Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase) 
  116.         { 
  117.             System.Drawing.Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height); 
  118.  
  119.             // 将位图背景填充为白色 
  120.             System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(destBmp); 
  121.             graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), 0, 0, destBmp.Width, destBmp.Height); 
  122.             graph.Dispose(); 
  123.  
  124.             double dBaseAxisLen = bXDir ? (double)destBmp.Height : (double)destBmp.Width; 
  125.  
  126.             for (int i = 0; i < destBmp.Width; i++) 
  127.             { 
  128.                 for (int j = 0; j < destBmp.Height; j++) 
  129.                 { 
  130.                     double dx = 0; 
  131.                     dx = bXDir ? (PI2 * (double)j) / dBaseAxisLen : (PI2 * (double)i) / dBaseAxisLen; 
  132.                     dx += dPhase; 
  133.                     double dy = Math.Sin(dx); 
  134.  
  135.                     // 取得当前点的颜色 
  136.                     int nOldX = 0, nOldY = 0; 
  137.                     nOldX = bXDir ? i + (int)(dy * dMultValue) : i; 
  138.                     nOldY = bXDir ? j : j + (int)(dy * dMultValue); 
  139.  
  140.                     System.Drawing.Color color = srcBmp.GetPixel(i, j); 
  141.                     if (nOldX >= 0 && nOldX < destBmp.Width 
  142.                      && nOldY >= 0 && nOldY < destBmp.Height) 
  143.                     { 
  144.                         destBmp.SetPixel(nOldX, nOldY, color); 
  145.                     } 
  146.                 } 
  147.             } 
  148.  
  149.             return destBmp; 
  150.         } 
  154.         #endregion 
  156.         #region 生成校验码图片 
  157.         public Bitmap CreateImageCode(string code) 
  158.         { 
  159.             int fSize = FontSize; 
  160.             int fWidth = fSize + Padding; 
  161.  
  162.             int imageWidth = (int)(code.Length * fWidth) + 4 + Padding * 2; 
  163.             int imageHeight = fSize * 2 + Padding; 
  164.  
  165.             System.Drawing.Bitmap image = new System.Drawing.Bitmap(imageWidth, imageHeight); 
  166.  
  167.             Graphics g = Graphics.FromImage(image); 
  168.  
  169.             g.Clear(BackgroundColor); 
  170.  
  171.             Random rand = new Random(); 
  172.  
  173.             //给背景添加随机生成的燥点 
  174.             if (this.Chaos) 
  175.             { 
  176.  
  177.                 Pen pen = new Pen(ChaosColor, 0); 
  178.                 int c = Length * 10; 
  179.  
  180.                 for (int i = 0; i < c; i++) 
  181.                 { 
  182.                     int x = rand.Next(image.Width); 
  183.                     int y = rand.Next(image.Height); 
  184.  
  185.                     g.DrawRectangle(pen, x, y, 1, 1); 
  186.                 } 
  187.             } 
  188.  
  189.             int left = 0, top = 0, top1 = 1, top2 = 1; 
  190.  
  191.             int n1 = (imageHeight - FontSize - Padding * 2); 
  192.             int n2 = n1 / 4; 
  193.             top1 = n2; 
  194.             top2 = n2 * 2; 
  195.  
  196.             Font f; 
  197.             Brush b; 
  198.  
  199.             int cindex, findex; 
  200.  
  201.             //随机字体和颜色的验证码字符 
  202.             for (int i = 0; i < code.Length; i++) 
  203.             { 
  204.                 cindex = rand.Next(Colors.Length - 1); 
  205.                 findex = rand.Next(Fonts.Length - 1); 
  206.  
  207.                 f = new System.Drawing.Font(Fonts[findex], fSize, System.Drawing.FontStyle.Bold); 
  208.                 b = new System.Drawing.SolidBrush(Colors[cindex]); 
  209.  
  210.                 if (i % 2 == 1) 
  211.                 { 
  212.                     top = top2; 
  213.                 } 
  214.                 else 
  215.                 { 
  216.                     top = top1; 
  217.                 } 
  218.  
  219.                 left = i * fWidth; 
  220.  
  221.                 g.DrawString(code.Substring(i, 1), f, b, left, top); 
  222.             } 
  223.  
  224.             //画一个边框 边框颜色为Color.Gainsboro 
  225.             g.DrawRectangle(new Pen(Color.Gainsboro, 0), 0, 0, image.Width - 1, image.Height - 1); 
  226.             g.Dispose(); 
  227.  
  228.             //产生波形（Add By 51aspx.com） 
  229.             image = TwistImage(image, true, 8, 4); 
  230.  
  231.             return image; 
  232.         } 
  233.         #endregion 
  235.         #region 将创建好的图片输出到页面 
  236.         public void CreateImageOnPage(string code, HttpContext context) 
  237.         { 
  238.             System.IO.MemoryStream ms = new System.IO.MemoryStream(); 
  239.             Bitmap image = this.CreateImageCode(code); 
  240.  
  241.             image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); 
  242.  
  243.             context.Response.ClearContent(); 
  244.             context.Response.ContentType = "image/Jpeg"; 
  245.             context.Response.BinaryWrite(ms.GetBuffer()); 
  246.  
  247.             ms.Close(); 
  248.             ms = null; 
  249.             image.Dispose(); 
  250.             image = null; 
  251.         } 
  252.         #endregion 
  254.         #region 生成随机字符码 
  255.         public string CreateVerifyCode(int codeLen) 
  256.         { 
  257.             if (codeLen == 0) 
  258.             { 
  259.                 codeLen = Length; 
  260.             } 
  261.  
  262.             string[] arr = CodeSerial.Split(','); 
  263.  
  264.             string code = ""; 
  265.  
  266.             int randValue = -1; 
  267.  
  268.             Random rand = new Random(unchecked((int)DateTime.Now.Ticks)); 
  269.  
  270.             for (int i = 0; i < codeLen; i++) 
  271.             { 
  272.                 randValue = rand.Next(0, arr.Length - 1); 
  273.  
  274.                 code += arr[randValue]; 
  275.             } 
  276.  
  277.             return code; 
  278.         } 
  279.         public string CreateVerifyCode() 
  280.         { 
  281.             return CreateVerifyCode(0); 
  282.         } 
  283.         #endregion 
  284. } 
PS：虽然不是我自己写的，但是可分享给大家。

代码中有注释，所以我就不多说了。

第三、生成调用类文件的网页（ValidateCode.aspx），在该页面的后台代码（ValidateCode.aspx.cs文件）的Page_Load事件中写如下代码：

[csharp] view plaincopyprint?
  1. protected void Page_Load(object sender, EventArgs e) 
  2. { 
  3.     validatedCode v = new validatedCode(); 
  4.     string code = v.CreateVerifyCode();            //取随机码 
  5.     v.CreateImageOnPage(code, this.Context);       // 输出图片 
  6.     Session["CheckCode"] = code;                   //Session 取出验证码 
  7. } 
第四、判断验证结果：Login.aspx页面的登录事件中添加验证
[csharp] view plaincopyprint?
  1. protected void btnLogin_Click(object sender, EventArgs e) 
  2.    { 
  3.        string vCode = Session["CheckCode"].ToString(); 
  4.        if (txtValidatedcode.Text.Trim().ToUpper() == vCode.ToUpper()) 
  5.        { 
  6.            ScriptManager.RegisterStartupScript(this.Page, this.GetType(), "Startup", "alert('ValidatedCode is right!');", true); 
  7.        } 
  8.    } 
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原文地址：https://www.cnblogs.com/51net/p/2902000.html