本文实例讲述了asp.net使用ashx生成图形验证码的方法。分享给大家供大家参考，具体如下：
验证码的好处不用我多说，你们都懂的。我在网上看到有人把验证码直接写在aspx页面里，也就是说这种方式请求验证码等于请求一个页面，这样做很不科学。如下所示
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<form id="form1" runat="server"> <div> <asp:Image ID="Image1" runat="server" ImageUrl="Default.aspx" /> <br /> <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox> <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" /> </div></form> |
这个代码看着就觉得写代码的人比较欠揍，代码写成这样子着实郁闷。验证吗也不写点script做下切换。
下面我介绍一种方式来实现这样的功能
1. 写个ashx生成图形验证码
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using System;using System.Collections;using System.Data;using System.Linq;using System.Web;using System.Web.Services;using System.Web.Services.Protocols;using System.Xml.Linq;using System.Web.SessionState;using System.Drawing;namespace usechecknum.ashx{ /// <summary> /// $codebehindclassname$ 的摘要说明 /// </summary> [WebService(Namespace = "http://tempuri.org/")] [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)] public class doCreateNum : IHttpHandler,IRequiresSessionState { public void ProcessRequest(HttpContext context) { context.Response.ContentType = "text/html"; string checkCode = GetValidation(5); // 产生5位随机验证码字符 context.Session["Code"] = checkCode; //将字符串保存到Session中，以便需要时进行验证 System.Drawing.Bitmap image = new System.Drawing.Bitmap(70, 22); Graphics g = Graphics.FromImage(image); try { //生成随机生成器 Random random = new Random(); //清空图片背景色 g.Clear(Color.White); // 画图片的背景噪音线 int i; for (i = 0; i < 25; 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); } Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold)); System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2F, true); g.DrawString(checkCode, font, brush, 2, 2); //画图片的前景噪音点 g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1); System.IO.MemoryStream ms = new System.IO.MemoryStream(); image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif); context.Response.ClearContent(); context.Response.ContentType = "image/Gif"; context.Response.BinaryWrite(ms.ToArray()); } finally { g.Dispose(); image.Dispose(); } } public string GetValidation(int num) { string str = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"; //"或者写汉字也行" string validatecode = ""; Random rd = new Random(); for (int i = 0; i < num; i++) { validatecode += str.Substring(rd.Next(0, str.Length), 1); } return validatecode; } public bool IsReusable { get { return false; } } }} |
2. 在页面上显示验证码，因为我们生成的是图形，所以可以直接写在<img/>标签里，我们只要写段简单的脚本就可以点击鼠标切换验证码了
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<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="index.aspx.cs" Inherits="usechecknum._Default" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" ><head runat="server"> <title>验证码的使用</title></head><script language="javascript" type="text/javascript"> function changeCode() { var imgNode = document.getElementById("vimg"); imgNode.src = "ashx/doCreateNum.ashx?t=" + (new Date()).valueOf(); // 这里加个时间的参数是为了防止浏览器缓存的问题 } </script><body> <form id="form1" runat="server"> 请输入验证码:<input type="text" name="checknum"/><img src="ashx/doCreateNum.ashx" id="vimg" onclick="changeCode()" /> </form></body></html> |
说了半天，该是时候看看生成的验证码长什么样了
希望本文所述对大家asp.net程序设计有所帮助。
