本文实例讲述了C#实现的一款比较美观的验证码。分享给大家供大家参考，具体如下：

using System;using System.Collections.Generic;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using System.Drawing;using System.IO;using System.Drawing.Imaging;public partial class ValidateCode : System.Web.UI.Page{ private int letterWidth = 16;//单个字体的宽度范围 private int letterHeight = 22;//单个字体的高度范围 private int letterCount = 4;//验证码位数 private char[] chars = "0123456789".ToCharArray(); private string[] fonts = { "Arial", "Georgia" }; /// <summary> /// 产生波形滤镜效果 /// </summary> private const double PI = 3.1415926535897932384626433832795; private const double PI2 = 6.283185307179586476925286766559; protected void Page_Load(object sender, EventArgs e) { //防止网页后退--禁止缓存 Response.Expires = 0; Response.Buffer = true; Response.ExpiresAbsolute = DateTime.Now.AddSeconds(-1); Response.AddHeader("pragma", "no-cache"); Response.CacheControl = "no-cache"; string str_ValidateCode = GetRandomNumberString(letterCount); HttpCookie objCookie = new HttpCookie("ValidateCode"); objCookie.Value = str_ValidateCode; objCookie.Path = "/"; objCookie.Expires = DateTime.Now.AddSeconds(1200); Response.Cookies.Add(objCookie); CreateImage(str_ValidateCode); } public void CreateImage(string checkCode) { int int_ImageWidth = checkCode.Length * letterWidth; Random newRandom = new Random(); Bitmap image = new Bitmap(int_ImageWidth, letterHeight); Graphics g = Graphics.FromImage(image); //生成随机生成器 Random random = new Random(); //白色背景 g.Clear(Color.White); //画图片的背景噪音线 for (int i = 0; i < 10; i++) { int x1 = random.Next(image.Width); int x2 = random.Next(image.Width); int y1 = random.Next(image.Height); int y2 = random.Next(image.Height); g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2); } //画图片的前景噪音点 for (int i = 0; i < 10; i++) { int x = random.Next(image.Width); int y = random.Next(image.Height); image.SetPixel(x, y, Color.FromArgb(random.Next())); } //随机字体和颜色的验证码字符 int findex; for (int int_index = 0; int_index < checkCode.Length; int_index++) { findex = newRandom.Next(fonts.Length - 1); string str_char = checkCode.Substring(int_index, 1); Brush newBrush = new SolidBrush(GetRandomColor()); Point thePos = new Point(int_index * letterWidth + 1 + newRandom.Next(3), 1 + newRandom.Next(3));//5+1+a+s+p+x g.DrawString(str_char, new Font(fonts[findex], 12, FontStyle.Bold), newBrush, thePos); } //灰色边框 g.DrawRectangle(new Pen(Color.LightGray, 1), 0, 0, int_ImageWidth - 1, (letterHeight - 1)); //图片扭曲 //image = TwistImage(image, true, 3, 4); //将生成的图片发回客户端 MemoryStream ms = new MemoryStream(); image.Save(ms, ImageFormat.Png); Response.ClearContent(); //需要输出图象信息 要修改HTTP头 Response.ContentType = "image/Png"; Response.BinaryWrite(ms.ToArray()); g.Dispose(); image.Dispose(); } /// <summary> /// 正弦曲线Wave扭曲图片 /// </summary> /// <param name="srcBmp">图片路径</param> /// <param name="bXDir">如果扭曲则选择为True</param> /// <param name="nMultValue">波形的幅度倍数，越大扭曲的程度越高，一般为3</param> /// <param name="dPhase">波形的起始相位，取值区间[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); // 将位图背景填充为白色 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); // 取得当前点的颜色 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; } public Color GetRandomColor() { Random RandomNum_First = new Random((int)DateTime.Now.Ticks); System.Threading.Thread.Sleep(RandomNum_First.Next(50)); Random RandomNum_Sencond = new Random((int)DateTime.Now.Ticks); int int_Red = RandomNum_First.Next(210); int int_Green = RandomNum_Sencond.Next(180); int int_Blue = (int_Red + int_Green > 300) ? 0 : 400 - int_Red - int_Green; int_Blue = (int_Blue > 255) ? 255 : int_Blue; return Color.FromArgb(int_Red, int_Green, int_Blue);// 5+1+a+s+p+x } // 生成随机数字字符串 public string GetRandomNumberString(int int_NumberLength) { Random random = new Random(); string validateCode = string.Empty; for (int i = 0; i < int_NumberLength; i++) validateCode += chars[random.Next(0, chars.Length)].ToString(); return validateCode; }}复制代码 代码如下:
<img alt="看不清，换一张" title="看不清，换一张" src="ValidateCode.aspx" style="cursor:pointer" onclick="this.src=this.src+'?r='+Math.random()" />

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