asp.net验证码新手教程

1、制作登录页面：先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。)代码如下：<asp:Image ID=“vcImg” ImageUrl="~/ValidateCode.aspx" runat="server" />

2、编写生成验证码的代码生成类文件 (命名：validatedCode）添加以下引用using System;using System.Web;using System.Drawin爿讥旌护g;/// <summary>/// Summary description for validatedCode/// </summary>public class validatedCode{ /// <summary> /// 验证码长度(默认6个验证码的长度) /// </summary> public int Length { get; set; } = 4; /// <summary> /// 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) /// </summary> public int FontSize { get; set; } = 40; /// <summary> /// 边框补(默认1像素) /// </summary> public int Padding { get; set; } = 2; /// <summary> /// 是否输出燥点(默认不输出) /// </summary> public bool Chaos { get; set; } = true; /// <summary> /// 输出燥点的颜色(默认灰色) /// </summary> public Color ChaosColor { get; set; } = Color.LightGray; /// <summary> /// 自定义背景色(默认白色) /// </summary> public Color BackgroundColor { get; set; } = Color.White; /// <summary> /// 自定义随机颜色数组 /// </summary> public Color[] Colors { get; set; } = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple }; /// <summary> /// 自定义字体数组 /// </summary> public string[] Fonts { get; set; } = { "Arial", "Georgia" }; /// <summary> /// 自定义随机码字符串序列(使用逗号分隔) /// </summary> public string CodeSerial { get; set; } = "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"; #region 产生波形滤镜效果 private const double PI = 3.1415926535897932384626433832795; private const double PI2 = 6.283185307179586476925286766559; /// <summary> /// 正弦曲线Wave扭曲图片（Edit By 51aspx.com） /// </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; } #endregion #region 生成校验码图片 public Bitmap CreateImageCode(string code) { int fSize = FontSize; int fWidth = fSize + Padding; int imageWidth = (int)(code.Length * fWidth) + 4 + 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(); //给背景添加随机生成的燥点 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; //随机字体和颜色的验证码字符 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); } //画一个边框 边框颜色为Color.Gainsboro g.DrawRectangle(new Pen(Color.Gainsboro, 0), 0, 0, image.Width - 1, image.Height - 1); g.Dispose(); //产生波形（Add By 51aspx.com） image = TwistImage(image, true, 8, 4); return image; } #endregion #region 将创建好的图片输出到页面 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 生成随机字符码 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}

3、编写调用网页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： protected void Page_Load(object sender, EventArgs e) { validatedCode v = new validatedCode(); string code = v.CreateVerifyCode(); //取随机码 v.CreateImageOnPage(code, this.Context); // 输出图片 Session["CheckCode"] = code; //Session 取出验证码 }

4、判断验证结果：Login.aspx页面的登录事件中添加验证protected void btnLogin_Click(object sender, Eve荏鱿胫协ntArgs e) { string vCode = Session["CheckCode"].ToString(); if (txtValidatedcode.Text.Trim().ToUpper() == vCode.ToUpper()) { ScriptManager.RegisterStartupScript(this.Page, this.GetType(), "Startup", "alert('验证码正确!');", true); } }