asp.net2.0生成一个复杂的验证码,背景随机,字体随机,中英文数字随机

来源：互联网发布：贵州大学网络课程登录编辑：程序博客网时间：2024/05/16 12:21

1、建立网站，添加一个网页ValitionNo.aspx，和Default.aspx，新建一个文件夹images。如图所示：
2、在images文件夹里添加以下５张图片：bg_0.jpg，bg_1.jpg，bg_2.jpg，bg_3.jpg，bg_4.jpg bg_0.jpg

bg_1.jpg

bg_2.jpg

bg_3.jpg

bg_4.jpg
3、ValitionNo.aspx里不用放任何控件，代码如下：

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="ValitionNo.aspx.cs" Inherits="guestBook_ValitionNo" %>

<!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>

4、双击页面ValitionNo.aspx进入ValitionNo.aspx.cs页面，按如下所示填充代码：

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.Imaging;
using System.Drawing.Drawing2D;
using System.Drawing;

public partial class guestBook_ValitionNo : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        Random rd = new Random(); //创建随机数对象

        //以下4行,产生由6个字母和数字组成的一个字符串
        string str = "ABCDEFGHIJKLMNOPQRSTURWXYZ0123456789想象是无限的";
        string yanzheng = "";
        for (int i = 0; i < 6; i++)
        {
            yanzheng = yanzheng + str.Substring(rd.Next(42), 1);
        }
        //验证码值存放到Session中用来比较
        Session["yanzheng"] = yanzheng;

        //以下三句,通过随机找一个现有图象产生一个画布Bitmap
        string bgFilePath = Server.MapPath(".//images//bg_" + new Random().Next(5) + ".jpg");//随机找个图象
        System.Drawing.Image imgObj = System.Drawing.Image.FromFile(bgFilePath);
        Bitmap newBitmap = new Bitmap(imgObj, 290, 80);//建立位图对象

        Graphics g = Graphics.FromImage(newBitmap);//根据上面创建的位图对象创建绘图面
        SolidBrush brush = new SolidBrush(Color.Blue);//设置画笔颜色

        //定义一个含10种字体的数组
        String[] ziti ={ "Arial", "Verdana", "Comic Sans MS", "Impact", "Haettenschweiler", "Lucida Sans Unicode", "Garamond", "Courier New", "Book Antiqua", "Arial Narrow" };

        //通过循环,绘制每个字符,
        for (int a = 0; a < yanzheng.Length; a++)
        {
            Font textFont = new Font(ziti[rd.Next(9)], 30, FontStyle.Bold);//字体随机,字号大小30,加粗
            //每次循环绘制一个字符,设置字体格式,画笔颜色,字符相对画布的X坐标,字符相对画布的Y坐标
            g.DrawString(yanzheng.Substring(a, 1), textFont, brush, 40 + a * 36, 20);
        }

        //保存画的图片到输出流中
        newBitmap.Save(Response.OutputStream, ImageFormat.Gif);

    }
}

5、在Default.aspx里添加一个文本框，图片按钮，Label标签和普通按钮，ImageButton的图片路径是~/ValitionNo.aspx，而不是某张图片。代码如下：

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_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>无标题页</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        验证码：<asp:TextBox ID="TextBox1" runat="server" Width="117px"></asp:TextBox>
        <asp:ImageButton ID="ImageButton1" runat="server" ImageUrl="~/ValitionNo.aspx" />
        <asp:LinkButton ID="LinkButton1" runat="server" CausesValidation="False">换一张</asp:LinkButton><br />
        <asp:Label ID="Label1" runat="server" ForeColor="Red"></asp:Label><br />
        <asp:Button ID="Button2" runat="server" Text="确定" OnClick="Button2_Click" /></div>
    </form>
</body>
</html>

6、在Default.aspx.cs里代码如下：

using System;
using System.Data;
using System.Configuration;
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;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void Button2_Click(object sender, EventArgs e)
    {
        if (Session["yanzheng"] != null && TextBox1.Text != Session["yanzheng"].ToString())
        {
            Label1.Text = "验证码错误！";
            return;
        }
        else
        {
            Label1.Text = "验证码正确！";
        }
    }
}

7、运行效果如下所示：

如果点验证码图片或者点换一张按钮，都可以使验证码随机改变，背景随机改变，数字字母汉字随机改变。