近日鐵路訂票網“12306”又出現多道另類考題，竟要訂票者在8個圖案中“點擊圖中所有美男子”、“請點擊下圖中所有的非智能眼鏡”、“請點擊下圖中所有的博斯普魯斯海峽”，網友吐槽：比高考題還難，到底是什么樣子的，先跟大家分享一下幾個例子：
哈哈，是有點奇葩的驗證碼，怪不得有人會說“媽媽我已經找不到回家”，這讓分秒必爭的春運網上搶票者瞬間傻眼，九成網友已經被打敗……
正巧小編最近也在研究驗證碼，參考了許多網上案例，整理了一篇文章特分享給大家。
驗證碼的一般編寫思路為：
1.定義驗證碼字符長度;
2.根據長度隨機生成驗證碼字符串;
3.將驗證碼字符串轉換成圖片形式，并在圖片中生成隨機噪聲點和聲線（對驗證碼進行模糊識別處理）;
4.顯示結果。
/// /// 生成隨機驗證碼 /// /// 驗證碼長度 /// public string CreateIdentifyingCode(int CodeLen) { if (CodeLen < 1) return String.Empty; int num; string checkcode = String.Empty; Random random = new Random(); for (int index = 0; index < CodeLen; index++) { num = random.Next(); if (num % 2 == 0) checkcode += (char)('0' + (char)(num % 10)); else checkcode += (char)('A' + (char)(num % 26)); } return checkcode; }------------------------------------------------------------------------------------------------- /// /// 生成驗證碼圖片 /// /// /// private void CreateCheckCodeImage(string checkcode) { if (checkcode == null || checkcode.Trim() == String.Empty) return; //創建圖片大小 System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling(checkcode.Length*12.5),22); //創建畫板 Graphics graphic = Graphics.FromImage(image); try { Random random = new Random(); graphic.Clear(Color.White); int x1 = 0, y1 = 0, x2 = 0, y2 = 0; //畫圖片背景噪聲線 for (int index = 0; index < 25; index++) { x1 = random.Next(image.Width); y1 = random.Next(image.Height); x2 = random.Next(image.Width); y2 = random.Next(image.Height); graphic.DrawLine(new Pen(Color.Silver),x1,y1,x2,y2); } Font font = new System.Drawing.Font("Helvetica", 12, (FontStyle.Bold |FontStyle.Italic)); LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),Color.Blue,Color.DarkBlue,1.2f,true); graphic.DrawString(checkcode,font,brush,2,2); int x = 0; int y = 0; // 畫圖片的前景噪聲點 for (int index = 0; index < 100; index++) { x = random.Next(image.Width); y = random.Next(image.Height); image.SetPixel(x,y,Color.FromArgb(random.Next())); } //畫圖片的邊框線 graphic.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1); //網頁響應 System.IO.MemoryStream ms = new System.IO.MemoryStream(); image.Save(ms,System.Drawing.Imaging.ImageFormat.Gif); Response.ClearContent(); Response.ContentType = "image/Gif"; Response.BinaryWrite(ms.ToArray()); } finally { graphic.Dispose(); image.Dispose(); } }以上所生成的為簡單的驗證碼。接下來我從其他的博客中學習了其他形式的效果。
/* 圖片畫線特殊效果：貝塞爾曲線 */ Graphics graph = Graphics.FromImage(image); graph.Clear(Color.WhiteSmoke); Point[] myArray ={ new Point(random.Next(150),random.Next(50)), new Point(random.Next(150),random.Next(50)), new Point(random.Next(150),random.Next(50)), new Point(random.Next(150),random.Next(50)), new Point(random.Next(150),random.Next(50)), new Point(random.Next(150),random.Next(50)), new Point(random.Next(150),random.Next(50)), new Point(random.Next(150),random.Next(50)), new Point(random.Next(150),random.Next(50)), new Point(random.Next(150),random.Next(50)) }; Pen myPen = new Pen(Color.Blue, 1); GraphicsPath myPath = new GraphicsPath(); myPath.AddBeziers(myArray); graph.DrawPath(myPen, myPath);驗證碼字符顏色變換效果：實現該效果，我們首先來定義一個顏色集合，然后通過for循環使其隨機改變字體顏色則可。
#region 定義顏色數組 Color[] colors = { Color.Blue, Color.Green, Color.Red, Color.Gold, Color.Black, Color.Chocolate, Color.Orange, Color.Purple }; public Color[] Colors { get { return colors; } set { colors = value; } } #endregion Brush brush; int colornum; for(int i=0; i { colornum = random.Next(Colors.Length - 1); brush = new System.Drawing.SolidBrush(Colors[cindex]); //利用DrawString函數進行顏色填充就可以了。 } 同樣的原理我們也可以定義一個字體的數組來進行驗證碼字體切換。代碼和顏色的類似，這里就不加以累贅。
接下來看看如何使得驗證碼的字體進行扭曲。
private const double PI = 3.1415926535897932384626433832795; private const double PI2 = 6.283185307179586476925286766559; /// /// 波形濾鏡效果函數 /// /// /// /// /// /// public System.Drawing.Bitmap TwistImage(Bitmap srcbmp, double dmultvalue, double dphase) { System.Drawing.Bitmap destbmp = new Bitmap(srcbmp.Width,srcbmp.Height); System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(destbmp); //填充背景圖為白色 graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), 0, 0, destbmp.Width, destbmp.Height); graph.Dispose(); double dbaselen = (double)destbmp.Width; for (int i = 0; i < destbmp.Width; i++) { for (int j = 0; j < destbmp.Height; j++) { double dx = 0; dx = (PI2 * (double)j) / dbaselen; dx += dphase; double dy = Math.Sin(dx); int noldx = 0, noldy = 0; noldx = i + (int)(dy * dmultvalue); noldy = j + (int)(dy * dmultvalue); System.Drawing.Color color = srcbmp.GetPixel(i, j); if (noldx >= 0 && noldx < destbmp.Width && noldy >= 0 && noldy < destbmp.Height) destbmp.SetPixel(noldx, noldy, color); } } return destbmp; }上面代碼是參考了這段代碼進行的學習<C#.net 好用的驗證碼代碼 漢字-變色-扭曲-波動 >，代碼如下
using System;using System.Data;using System.Configuration;using System.Collections;using System.Drawing;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Web.UI.HtmlControls;public partial class study_CheckCode2 : System.Web.UI.Page{ protected void Page_Load(object sender, EventArgs e) { string code = CreateVerifyCode(); //取隨機碼 CreateImageOnPage(code, this.Context); // 輸出圖片 Response.Cookies.Add(new HttpCookie("CheckCode", code.ToUpper()));// 使用Cookies取驗證碼的值 } #region 驗證碼長度(默認4個驗證碼的長度) int length = 4; public int Length { get { return length; } set { length = value; } } #endregion #region 驗證碼字體大小(為了顯示扭曲效果，默認40像素，可以自行修改) int fontSize = 40; public int FontSize { get { return fontSize; } set { fontSize = value; } } #endregion #region 邊框補(默認1像素) int padding = 2; public int Padding { get { return padding; } set { padding = value; } } #endregion #region 是否輸出燥點(默認不輸出) bool chaos = true; public bool Chaos { get { return chaos; } set { chaos = value; } } #endregion #region 輸出燥點的顏色(默認灰色) Color chaosColor = Color.LightGray; public Color ChaosColor { get { return chaosColor; } set { chaosColor = value; } } #endregion #region 自定義背景色(默認白色) Color backgroundColor = Color.White; public Color BackgroundColor { get { return backgroundColor; } set { backgroundColor = value; } } #endregion #region 自定義隨機顏色數組 Color[] colors = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple }; public Color[] Colors { get { return colors; } set { colors = value; } } #endregion #region 自定義字體數組 string[] fonts = { "Arial", "Georgia" }; public string[] Fonts { get { return fonts; } set { fonts = value; } } #endregion #region 自定義隨機碼字符串序列(使用逗號分隔) //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"; string codeSerial = "阿,保,持,的,法,規,和,東,三,省,問,我,惹,你,誒,沒,改,變,揍,屁,股,吧"; public string CodeSerial { get { return codeSerial; } set { codeSerial = value; } } #endregion #region 產生波形濾鏡效果 private const double PI = 3.1415926535897932384626433832795; private const double PI2 = 6.283185307179586476925286766559; /// <summary> /// 正弦曲線Wave扭曲圖片（Edit By 51aspx.com） /// </summary> /// <param name="srcBmp">圖片路徑</param> /// <param name="bXDir">如果扭曲則選擇為True</param> /// <param name="dMultValue">波形的幅度倍數，越大扭曲的程度越高，一般為3</param> /// <param name="dPhase">波形的起始相位，取值區間[0-2*PI)</param> /// <returns></returns> public System.Drawing.Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase) { System.Drawing.Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height); // 將位圖背景填充為白色 System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(destBmp); graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), 0, 0, destBmp.Width, destBmp.Height); graph.Dispose(); double dBaseAxisLen = bXDir ? (double)destBmp.Height : (double)destBmp.Width; for (int i = 0; i < destBmp.Width; i++) { for (int j = 0; j < destBmp.Height; j++) { double dx = 0; dx = bXDir ? (PI2 * (double)j) / dBaseAxisLen : (PI2 * (double)i) / dBaseAxisLen; dx += dPhase; double dy = Math.Sin(dx); // 取得當前點的顏色 int nOldX = 0, nOldY = 0; nOldX = bXDir ? i + (int)(dy * dMultValue) : i; nOldY = bXDir ? j : j + (int)(dy * dMultValue); System.Drawing.Color color = srcBmp.GetPixel(i, j); if (nOldX >= 0 && nOldX < destBmp.Width && nOldY >= 0 && nOldY < destBmp.Height) { destBmp.SetPixel(nOldX, nOldY, color); } } } return destBmp; } #endregion #region 生成校驗碼圖片 public Bitmap CreateImageCode(string code) { int fSize = FontSize; int fWidth = fSize + Padding; int imageWidth = (int)(code.Length * fWidth) + 30 + Padding * 2; int imageHeight = fSize * 2 + Padding; System.Drawing.Bitmap image = new System.Drawing.Bitmap(imageWidth, imageHeight); Graphics g = Graphics.FromImage(image); g.Clear(BackgroundColor); Random rand = new Random(); //給背景添加隨機生成的燥點 if (this.Chaos) { Pen pen = new Pen(ChaosColor, 0); int c = Length * 10; for (int i = 0; i < c; i++) { int x = rand.Next(image.Width); int y = rand.Next(image.Height); g.DrawRectangle(pen, x, y, 1, 1); } } int left = 0, top = 0, top1 = 1, top2 = 1; int n1 = (imageHeight - FontSize - Padding * 2); int n2 = n1 / 4; top1 = n2; top2 = n2 * 2; Font f; Brush b; int cindex, findex; //隨機字體和顏色的驗證碼字符 for (int i = 0; i < code.Length; i++) { cindex = rand.Next(Colors.Length - 1); findex = rand.Next(Fonts.Length - 1); f = new System.Drawing.Font(Fonts[findex], fSize, System.Drawing.FontStyle.Bold); b = new System.Drawing.SolidBrush(Colors[cindex]); if (i % 2 == 1) { top = top2; } else { top = top1; } left = i * fWidth; g.DrawString(code.Substring(i, 1), f, b, left, top); } //畫一個邊框 邊框顏色為Color.Gainsboro g.DrawRectangle(new Pen(Color.Gainsboro, 0), 0, 0, image.Width - 1, image.Height - 1); g.Dispose(); //產生波形（Add By 51aspx.com） image = TwistImage(image, true, 8, 4); return image; } #endregion #region 將創建好的圖片輸出到頁面 public void CreateImageOnPage(string code, HttpContext context) { System.IO.MemoryStream ms = new System.IO.MemoryStream(); Bitmap image = this.CreateImageCode(code); image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); context.Response.ClearContent(); context.Response.ContentType = "image/Jpeg"; context.Response.BinaryWrite(ms.GetBuffer()); ms.Close(); ms = null; image.Dispose(); image = null; } #endregion #region 生成隨機字符碼 public string CreateVerifyCode(int codeLen) { if (codeLen == 0) { codeLen = Length; } string[] arr = CodeSerial.Split(','); string code = ""; int randValue = -1; Random rand = new Random(unchecked((int)DateTime.Now.Ticks)); for (int i = 0; i < codeLen; i++) { randValue = rand.Next(0, arr.Length - 1); code += arr[randValue]; } return code; } public string CreateVerifyCode() { return CreateVerifyCode(0); } #endregion}一年一度的搶票熱潮又開始了，希望大家都能順利買到回家的火車篇，回家過年，突然感覺有點年味了，一年又一年，時間都去哪了，小小的感慨一下……
言歸正傳，這就是為大家分享的C#驗證碼程序，和12306驗證碼差多了，不過也是小編的學習收獲吧！大家也可以結合下面這兩篇文章進行學習：
《12306動態驗證碼啟發之ASP.NET實現動態GIF驗證碼(附源碼)》
希望本文所述對大家學習驗證碼技術有所幫助。
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