ASP.NET生成随机验证码代码和看不清切换验证码的小结

xiaoxiao2025-02-12 17

经过亲自测试，本代码复制并按照说明，可以直接运行

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using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using System.Drawing;using System.IO;

public partial class CheckCode : System.Web.UI.Page{ protected void Page_Load(object sender, EventArgs e) { this.CreateCheckCodeImage(GenerateCheckCode()); }

/// <summary> /// 创建随机生成的验证码，可以为数字或字母 /// </summary> /// <returns></returns> private string GenerateCheckCode() { int number = 0; char code; string checkcode = string.Empty;

// 随机生成数字，并转换成5个数字或字母 System.Random random = new Random(); for (int i = 0; i < 5; i++) { number = random.Next(); if (number % 2 == 0) code = (char)('0' + (char)(number % 10)); // 数字 else code = (char)('A' + (char)(number % 26)); // 字母

checkcode += code.ToString(); } Response.Cookies.Add(new HttpCookie("CheckCode", checkcode)); return checkcode; }

/// <summary> /// 创建随机验证的图片，包括背景色和前景色 /// </summary> /// <param name="checkcode"></param> private void CreateCheckCodeImage(string checkcode) { if (checkcode == null || checkcode.Trim() == string.Empty) return;

Bitmap image = new Bitmap((int)Math.Ceiling((checkcode.Length * 12.8)), 24); Graphics grp = Graphics.FromImage(image);

try { // 产生随机生成码 Random random = new Random();

// 清空图片背景色 grp.Clear(Color.White);

// 画图片的背景噪音线 for (int 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);

grp.DrawLine(new Pen(Color.SpringGreen), x1, x2, y1, y2); } Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic)); 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); grp.DrawString(checkcode, font, brush, 2, 2);

// 画图片的前景噪音点 for (int i = 0; i < 100; i++) { int x = random.Next(image.Width); int y = random.Next(image.Height);

image.SetPixel(x, y, Color.FromArgb(random.Next())); }

// 画图片的边框线 grp.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);

MemoryStream ms = new MemoryStream(); image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif); Response.ClearContent(); Response.ContentType = "image/Gif"; Response.BinaryWrite(ms.ToArray()); } catch (System.Exception ex) { Response.Write(ex.Message); } finally { // 清除类对象(Graphics和Bitmap) grp.Dispose(); image.Dispose(); grp = null; image = null; } }}

生成随机验证码的配置说明：

假如以上验证码生成器页面名为：CheckCode.aspx，那么在登录页面中使用“<IMG>” 这个 HTML 元素来显示生成的验证码图片：<IMG src="CheckCode.aspx">　　在登录页面的登录按钮的处理事件中使用以下代码判断验证码：

private void btnLogin_Click(object sender, System.Web.UI.ImageClickEventArgs e){if(Request.Cookies["CheckCode"] == null){lblMessage.Text = "您的浏览器设置已被禁用 Cookies，您必须设置浏览器允许使用 Cookies 选项后才能使用本系统。";lblMessage.Visible = true;return;}

if(String.Compare(Request.Cookies["CheckCode"].Value, txtCheckCode.Text, true) != 0){lblMessage.Text = "验证码错误，请输入正确的验证码。";lblMessage.Visible = true;return;}

添加图片，便切换验证码设置：

转载声明：本文转自http://wyzhjmy.blog.163.com/blog/static/7234753520093353751852/

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另外，亦可参考：

无刷新更换验证码

现在越来越多的网站的注册、发布等页面都采用了防止一些恶意程序的图片验证码选项，不知道大家有没有碰到这样的情况，一个注册表单，填写了帐号信息、个人信息，最后一项的验证码太模糊了竟然看不清，只能是重新刷新整个页面来刷新图片验证码的内容，这是一个不良好的交互设计。参考了一些门户网站的方法，我的改进设计思路如下：把验证码输入项放在表单的第一行；客户端可以在不刷新整个页面的情况下更新图片验证码的内容。我们一般要插入验证码都是使用<img />标签，例如<img src="validate.aspx" />，其中validate.aspx是一个生成图片的程序文件。为了能够更新验证码的内容，可以在图片旁边加一个更新的链接，单击触发图片重载事件，完成图片验证码的更换。具体代码如下：

注意：在reloadcode函数中，我们在code.asp后面加了一个随机参数，这样每次的链接地址都不一样，从而达到更新的目的。

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无刷新更换验证码

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<img src="manage_product_checkCode.aspx" id="safecode" alt="看不清，点击换张验证码"/> <a href="javascript:reloadcode()" title="更换一张验证码图片">更换一张验证码图片 </a>

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转载声明：本文转自http://czm600604604.blog.163.com/blog/static/8252068200981091443438/

无刷新更换验证码

页面中代码

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图形验证码+“看不清楚换一张”

Image.aspx.cs 中代码

using System;using System.Data;using System.Configuration;using System.Collections;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Web.UI.HtmlControls;using System.Drawing;using System.Drawing.Text;using System.Drawing.Drawing2D;using System.Drawing.Imaging;using System.Drawing.Design;

//生成随机字符串public partial class Image : System.Web.UI.Page{ private string CreateRandomNum(int NumCount) { string allChar = "0,1,2,3,4,5,6,7,8,9"; string[] allCharArray = allChar.Split(','); string randomNum = ""; int temp = +1; Random rand = new Random(); for (int i = 0; i < NumCount; i++) { if (temp != -1) { rand = new Random(temp * ((int)DateTime.Now.Ticks)); } int t = rand.Next(10); if (temp == t) { return CreateRandomNum(NumCount); } temp = t; randomNum += allCharArray[t]; } return randomNum; } //生成图片 private void CreateImage(string validateNum) { if (validateNum == null || validateNum.Trim() == String.Empty) return; System.Drawing.Bitmap image = new System.Drawing.Bitmap(validateNum.Length * 12 + 10, 22); Graphics g = Graphics.FromImage(image); try { Random random = new Random(); g.Clear(Color.White); for (int 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, x2, y1, 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(validateNum, font, brush, 2, 2); for (int i = 0; i < 100; i++) { int x = random.Next(image.Width); int y = random.Next(image.Height); image.SetPixel(x, y, Color.FromArgb(random.Next())); } 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); Response.ClearContent(); Response.ContentType = "image/Gif"; Response.BinaryWrite(ms.ToArray()); } finally { g.Dispose(); image.Dispose(); } } protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { string validateNum = CreateRandomNum(4); CreateImage(validateNum); Session["ValidateNum"] = validateNum; } }}

页面中代码

转载声明：本文转自http://zzpdownload.blog.163.com/blog/static/83231134200912643320729/

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Javascript 验证码（尚未验证）

需要用到验证码，突然想能否用js做验证码呢？当然js不能作图，但是可以用js模拟做验证码的于是花了20分钟按照我的想法尝试做，最后做出来比我想象中的效果还要好，呵呵先贴个图看看代码：

<!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> <title>无标题页</title> <style type="text/css"> .code { background-image:url(code.jpg); font-family:Arial; font-style:italic; color:Red; border:0; padding:2px 3px; letter-spacing:3px; font-weight:bolder; } .unchanged { border:0; } </style> <script language="javascript" type="text/javascript"> var code ; //在全局定义验证码 function createCode() { code = ""; var codeLength = 6;//验证码的长度 var checkCode = document.getElementById("checkCode"); var selectChar = new Array(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');//所有候选组成验证码的字符，当然也可以用中文的 for(var i=0;i<codeLength;i++) { var charIndex = Math.floor(Math.random()*36); code +=selectChar[charIndex]; } // alert(code); if(checkCode) { checkCode.className="code"; checkCode.value = code; } } function validate () { var inputCode = document.getElementById("input1").value; if(inputCode.length <=0) { alert("请输入验证码！"); } else if(inputCode != code ) { alert("验证码输入错误！"); createCode();//刷新验证码 } else { alert("^-^ OK"); } } </script> </head> <body> <form action="#"> <input type="text" οnclick="createCode()" id="input1" /> <input type="text" id="checkCode" class="unchanged" style="width: 80px" /><br /> <input id="Button1" οnclick="validate();" type="button" value="确定" /> </form> </body> </html>

转载声明：本文转自http://www.chenjiliang.com/Article/View.aspx?ArticleID=5449

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