asp.net使用ashx生成图形验证码的方法示例

2024-07-10 13:32:35

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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

<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

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

<%@ 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

asp.net,ashx,生成,图形,验证码