HTML实现验证码 | 易学教程

第一步:添加一个页面,页面代码如下:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="CheckCode.aspx.cs" Inherits="CheckCode" %>

<!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>无标题页</title>
</head>
<body>
<form id="form1" runat="server">
<div>

</div>
</form>
</body>
</html>
第二步:添加页面的cs代码:
using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Drawing;
//这是一个生成验证码的网页
public partial class CheckCode : System.Web.UI.Page
{
private string GenerateCheckCode()
{
int num;
char code;
string checkCode = string.Empty;
Random random = new Random();
for (int i = 0; i < 6; i++)//循环次数决定验证码的位数
{
num = random.Next();
if (num % 2 == 0)
{
code = (char)('0' + (char)(num % 10));
}
else
{
code = (char)('A' + (char)(num % 26));
}

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

protected void Page_Load(object sender, EventArgs e)
{
CreateCheckCodeImg(GenerateCheckCode());
}

private void CreateCheckCodeImg(string checkCode)
{
if (checkCode == null || checkCode.Trim() == String.Empty)
return;
Bitmap img = new Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22);

Graphics g = Graphics.FromImage(img);
try
{
Random random = new Random();
g.Clear(Color.White);

//画图片的背景线
for (int i = 0; i < 2; i++)
{
int x1 = random.Next(img.Width);
int x2 = random.Next(img.Width);
int y1 = random.Next(img.Width);
int y2 = random.Next(img.Width);
g.DrawLine(new Pen(Color.Black), x1, y1, x2, y2);
}

//画出指定的字符
Font font = new Font("Arial", 12, (FontStyle.Bold));
System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, img.Width, img.Height), Color.Blue, Color.Red, 1.2f, true);
g.DrawString(checkCode, font, brush, 2, 2);

//画图片的前景噪点
for (int i = 0; i < 100; i++)
{
int x = random.Next(img.Width);
int y = random.Next(img.Height);
img.SetPixel(x, y, Color.FromArgb(random.Next()));
}
g.DrawRectangle(new Pen(Color.Silver),0,0,img.Width-1,img.Height-1);
System.IO.MemoryStream ms=new System.IO.MemoryStream();
img.Save(ms,System.Drawing.Imaging.ImageFormat.Gif);
Response.ClearContent();
Response.ContentType="image/Gif";
Response.BinaryWrite(ms.ToArray());

}
finally
{
g.Dispose();
img.Dispose();
}
}

}

第三步:在需要验证码的网页引用产生验证码的网页:
在你需要调用验证码的网页中添加一个<img>标签,将img标签的src设置成刚刚新添加的那个aspx!比如<img alt="验证码" src="CkeckCode.aspx"></img>
下面是刷新功能:
你可以把img标签和一个linkbutton一起加入到updatepanel中,然后生成一个linkbutton的click事件,不用在里面写任何代码的,就可以达到刷新验证码的效果了.

最后一步:验证验证码:
在验证页面里添加以下代码:
HttpCookie cookie = Request.Cookies["CheckCode"];

if (cookie.Value == tbYanZM.Text)
{
Response.Write("...验证码正确");

}

来源：CSDN

作者：逸磊无双

链接：https://blog.csdn.net/qiaolei654658/article/details/6905160

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验证码

html代码

system

string

response