效果：
思路：
借用ashx文件創建四位驗證，首先生成四位隨機數字。然后創建畫布，再將創建好的驗證碼存入session,然后前臺進行button按鈕將文本框中的值進行ajax請求到后臺，和session中的驗證碼進行對比，成功返回true,失敗返回false.
代碼：
【前臺】
1 <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="verifycodeDemo.aspx.cs" Inherits="verifycodeDemo.verifycodeDemo" %> 2 3 <!DOCTYPE html> 4 5 <html xmlns="http://www.w3.org/1999/xhtml"> 6 <head runat="server"> 7 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 8 <title>青蘋果驗證碼例子</title> 9 <script src="jquery-1.3.2.min.js"></script>10 <script type="text/javascript">11 //切換驗證碼12 function ToggleCode(obj, codeurl) {13 $("#" + obj).attr("src", codeurl + "?time=" + Math.random());14 }15 //ajax提交后臺驗證16 function postAjax() {17 var VerifyCodeValue = $("#txtVerifyCode").val();18 $.ajax({19 type: 'post',20 dataType: "text",21 url: "verifycodeDemo.aspx",22 data: "action=comparison&VerifyCode=" + VerifyCodeValue,23 cache: false,24 async: false,25 success: function (msg) {26 if (msg == "false") {27 alert("驗證失敗!sorry,青蘋果");28 ToggleCode("Verify_codeImag", "VerifyCode.ashx");29 $("#txtVerifyCode").val("");30 }31 else {32 alert("驗證成功！hello,青蘋果!");33 }34 }35 });36 }37 </script>38 </head>39 <body>40 <form id="form1" runat="server">41 <div>42 <input type="text" id="txtVerifyCode" />43 <img src="VerifyCode.ashx" id="Verify_codeImag" alt="點擊切換驗證碼" style="CURSOR: pointer" width="65" height="25" title="點擊切換驗證碼" onclick="ToggleCode(this.id, 'VerifyCode.ashx');return false;" />44 <input type="button" value="青蘋果驗證碼" onclick="postAjax()" />45 </div>46 </form>47 </body>48 </html>
【后臺】
1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Web; 5 using System.Web.UI; 6 using System.Web.UI.WebControls; 7 8 namespace verifycodeDemo 9 {10 public partial class verifycodeDemo : System.Web.UI.Page11 {12 PRotected void Page_Load(object sender, EventArgs e)13 {14 string action = Request.Params["action"];15 string VerifyCodeValue = Request.Params["VerifyCode"];16 if (action == "comparison")17 {18 string Msg = "true";19 //對session中存儲的驗證碼對比20 if (HttpContext.Current.Session["dt_session_code"] == null || VerifyCodeValue.ToLower() != HttpContext.Current.Session["dt_session_code"].ToString().ToLower())21 {22 Msg = "false";//驗證碼輸入不正確23 }24 Response.Write(Msg);25 Response.End();26 }27 28 }29 }30 }【ashx文件】
1 using System; 2 using System.Collections.Generic; 3 using System.Drawing; 4 using System.Drawing.Imaging; 5 using System.IO; 6 using System.Linq; 7 using System.Web; 8 using System.Web.SessionState; 9 10 11 namespace ESoftMS.Web.Frame 12 { 13 /// <summary> 14 /// VerifyCode 的摘要說明 青蘋果(m.survivalescaperooms.com/xinchun) 15 /// </summary> 16 public class VerifyCode : IHttpHandler, IRequiresSessionState 17 { 18 19 public void ProcessRequest(HttpContext context) 20 { 21 int codeW = 80; 22 int codeH = 22; 23 int fontSize = 16; 24 string chkCode = string.Empty; 25 //顏色列表，用于驗證碼、噪線、噪點 26 Color[] color = { Color.Black, Color.Red, Color.Blue, Color.Green, Color.Orange, Color.Brown, Color.Brown, Color.DarkBlue }; 27 //字體列表，用于驗證碼 28 string[] font = { "Times New Roman", "Verdana", "Arial", "Gungsuh", "Impact" }; 29 //驗證碼的字符集，去掉了一些容易混淆的字符 30 char[] character = { '2', '3', '4', '5', '6', '8', '9', 'a', 'b', 'd', 'e', 'f', 'h', 'k', 'm', 'n', 'r', 'x', 'y', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'R', 'S', 'T', 'W', 'X', 'Y' }; 31 Random rnd = new Random(); 32 //生成驗證碼字符串 33 for (int i = 0; i < 4; i++) 34 { 35 chkCode += character[rnd.Next(character.Length)]; 36 } 37 //寫入Session 38 context.Session["dt_session_code"] = chkCode; 39 //創建畫布 40 Bitmap bmp = new Bitmap(codeW, codeH); 41 Graphics g = Graphics.FromImage(bmp); 42 g.Clear(Color.White); 43 //畫噪線 44 for (int i = 0; i < 1; i++) 45 { 46 int x1 = rnd.Next(codeW); 47 int y1 = rnd.Next(codeH); 48 int x2 = rnd.Next(codeW); 49 int y2 = rnd.Next(codeH); 50 Color clr = color[rnd.Next(color.Length)]; 51 g.DrawLine(new Pen(clr), x1, y1, x2, y2); 52 } 53 //畫驗證碼字符串 54 for (int i = 0; i < chkCode.Length; i++) 55 { 56 string fnt = font[rnd.Next(font.Length)]; 57 Font ft = new Font(fnt, fontSize); 58 Color clr = color[rnd.Next(color.Length)]; 59 g.DrawString(chkCode[i].ToString(), ft, new SolidBrush(clr), (float)i * 18 + 2, (float)0); 60 } 61 ////畫噪點 62 //for (int i = 0; i < 1; i++) 63 //{ 64 // int x = rnd.Next(bmp.Width); 65 // int y = rnd.Next(bmp.Height); 66 // Color clr = color[rnd.Next(color.Length)]; 67 // bmp.SetPixel(x, y, clr); 68 //} 69 //清除該頁輸出緩存，設置該頁無緩存 70 context.Response.Buffer = true; 71 context.Response.ExpiresAbsolute = System.DateTime.Now.AddMilliseconds(0); 72 context.Response.Expires = 0; 73 context.Response.CacheControl = "no-cache"; 74 context.Response.AppendHeader("Pragma", "No-Cache"); 75 //將驗證碼圖片寫入內存流，并將其以 "image/Png" 格式輸出 76 MemoryStream ms = new MemoryStream(); 77 try 78 { 79 bmp.Save(ms, ImageFormat.Png); 80 context.Response.ClearContent(); 81 context.Response.ContentType = "image/Gif"; 82 context.Response.BinaryWrite(ms.ToArray()); 83 } 84 catch (Exception) 85 { 86 87 } 88 finally 89 { 90 g.Dispose(); 91 bmp.Dispose(); 92 } 93 } 94 95 public bool IsReusable 96 { 97 get 98 { 99 return false;100 }101 }102 }103 }Demo下載：
http://files.VEVb.com/xinchun/verifycodeDemo.rar
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