asp.net实现登录页验证码功能

最新推荐文章于 2019-06-03 10:14:18 发布

原创最新推荐文章于 2019-06-03 10:14:18 发布 · 5.9k 阅读

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本文介绍了一个使用ASP.NET、C#和HTML实现的验证码系统。该系统包括前后端代码，通过生成随机字符并显示为图片，用户需输入看到的验证码进行验证。文章提供了完整的代码示例，包括Default.aspx页面的HTML和C#逻辑，以及ImageCode.aspx页面的验证码生成代码。

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一、效果

二、实现代码:

项目资源分布

主页Default.aspx

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

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
       <script src="jq/jquery-3.3.1.js" type="text/javascript"></script> 
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <table runat="server" >
         <tr>
                <td>
                    <asp:Label ID="Label3" runat="server" Text="验证码" Font-Size="30px"></asp:Label>
                </td>
                <td >
                 <asp:TextBox ID="tbx_yzm" runat="server" Width="70px"></asp:TextBox>          
                    <asp:ImageButton ID="ibtn_yzm"  src="/ImageCode.aspx"  runat="server" Width="70px" Height="40px" />
                    <a href="javascript:changeCode()"style="text-decoration: underline; font-size:10px;">换一张</a>
                    <script type="text/javascript">
                    function changeCode() 
                    {
                    document.getElementById('ibtn_yzm').src = document.getElementById('ibtn_yzm').src + '?';
                    }
                    </script>
                    <asp:Button ID="Button1" runat="server" Text="验证" OnClick="Button1_Click" />
                </td>
            </tr>
          </table>
    </div>
    </form>
</body>
</html>

Default.aspx.cs

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

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

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        string code = tbx_yzm.Text;
        HttpCookie htco = Request.Cookies["ImageV"];
        string scode = htco.Value.ToString();
        if (code.ToUpper() != scode)
        {
            Response.Write("<script>alert('验证码输入不正确！')</script>");
        }
        else
        {
            this.tbx_yzm.Text = "";
            Response.Write("<script>alert('验证码输入正确！')</script>");
        }
    }
}

ImageCode.aspx(啥也不用动)

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

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    
    </div>
    </form>
</body>
</html>

ImageCode.aspx.cs

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

public partial class ImageCode : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string tmp = RndNum(4);
        HttpCookie a = new HttpCookie("ImageV ", tmp);
        Response.Cookies.Add(a);
        this.ValidateCode(tmp);
    }
    private void ValidateCode(string VNum)
    {

        Bitmap Img = null;

        Graphics g = null;

        MemoryStream ms = null;

        int gheight = VNum.Length * 12;

        Img = new Bitmap(gheight, 25);

        g = Graphics.FromImage(Img);

        //生成随机生成器

        Random random = new Random();

        //背景颜色
        g.Clear(Color.White);

        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()));

        }


        //文字字体
        Font f = new Font("Arial Black ", 12);

        //文字颜色
        SolidBrush s = new SolidBrush(Color.Blue);

        g.DrawString(VNum, f, s, 3, 3);

        ms = new MemoryStream();

        Img.Save(ms, ImageFormat.Jpeg);

        Response.ClearContent();

        Response.ContentType = "image/Jpeg ";

        Response.BinaryWrite(ms.ToArray());

        g.Dispose();
        Img.Dispose();
        Response.End();

    }
    private string RndNum(int VcodeNum)
    {

        string Vchar = "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";

        string[] VcArray = Vchar.Split(new Char[] { ',' });

        string VNum = " ";
        int temp = -1;
        Random rand = new Random();

        for (int i = 1; i < VcodeNum + 1; i++)
        {
            if (temp != -1)
            {
                rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks));

            }
            int t = rand.Next(35);
            if (temp != -1 && temp == t)
            {
                return RndNum(VcodeNum);

            }
            temp = t;
            VNum += VcArray[t];

        }

        return VNum;

    }
}