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.Net 登陆的时候添加验证码

一、ASPX 登陆界面验证码

1、登陆验证码图片和输入验证码框

<asp:TextBox ID="txtValiCode" runat="server" Width="50px"></asp:TextBox>
<asp:Image ID="ValiCode" ImageUrl="CreateValiImg.aspx" runat="server" style="position:relative;top:4px;" />

2、js

 $(function () {
            $("#loginBtn").click(function () {
                var Pwd = $("#PwdTbx").val();
                var md5pwd = $.md5(Pwd);
                $("#PwdTbx").val(md5pwd);

            });
            $("#txtValiCode").val("");

            $("#ValiCode").click(function () {
                location.reload();
            });
            
        });

View Code

3、创建生产验证码的aspx页 CreateValiImg.aspx

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

<!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>

View Code

后台代码

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

public partial class CreateValiImg : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string validateNum = CreateRandomNum(4);
        CreateImage(validateNum);
        Session["ValidateNum"] = validateNum;
    }

    //生产随机数
    private string CreateRandomNum(int NumCount)
    {
        string allChar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,O,P,Q,R,S,T,U,W,X,Y,Z,a,b,c,d,e,f,g,h,i,j,k,m,n,o,p,q,s,t,u,w,x,y,z";
        string[] allCharArray = allChar.Split(',');//拆分成数组
        string randomNum = "";
        int temp = -1;                             //记录上次随机数的数值，尽量避免产生几个相同的随机数
        Random rand = new Random();
        for (int i = 0; i < NumCount; i++)
        {
            if (temp != -1)
            {
                rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
            }
            int t = rand.Next(35);
            if (temp == t)
            {
                return CreateRandomNum(NumCount);
            }
            temp = t;
            randomNum += allCharArray[t];


        }
        return randomNum;
    }
    //生产图片
    private void CreateImage(string validateNum)
    {
        if (validateNum == null || validateNum.Trim() == string.Empty)
            return;
        //生成BitMap图像
        System.Drawing.Bitmap image = new System.Drawing.Bitmap(validateNum.Length * 12 + 12, 22);
        Graphics g = Graphics.FromImage(image);
        try
        {
            //生成随机生成器
            Random random = new Random();
            //清空图片背景
            g.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);
                g.DrawLine(new Pen(Color.Silver), x1, x2, y1, y2);
            }
            Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.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);
            g.DrawString(validateNum, 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
            g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            //将图像保存到指定流
            image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
            Response.ClearContent();
            Response.ContentType = "image/Gif";
            Response.BinaryWrite(ms.ToArray());
        }
        finally
        {
            g.Dispose();
            image.Dispose();
        }
    }
}

View Code

4、运行效果

5、登陆提交账号密码验证码的时候验证

if (ValiCode != Session["ValidateNum"].ToString()){ ... }

二、MVC中使用验证码

1、在登陆页添加输入验证码框和图片

 验证码 <input ID="txtValiCode" type="text"  style="60px;" />
       <img ID="ValiCode" src="/Login/CreatevaliImg"   style="position:relative;top:4px;" />

2、登陆界面js、点击验证码图片刷新验证码

  $(function () {     
        $("#txtValiCode").val("");
        $("#ValiCode").click(function () {
            location.reload();
        });
    });

3、在controller里添加 CreatevaliImg 方法生产验证码，供界面里img url调用

 public void CreatevaliImg()
        {
            string validateNum = CreateRandomNum(4);
            CreateImage(validateNum);
            Session["ValidateNum"] = validateNum;
        }

        //生产随机数
        private string CreateRandomNum(int NumCount)
        {
            string allChar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,O,P,Q,R,S,T,U,W,X,Y,Z,a,b,c,d,e,f,g,h,i,j,k,m,n,o,p,q,s,t,u,w,x,y,z";
            string[] allCharArray = allChar.Split(',');//拆分成数组
            string randomNum = "";
            int temp = -1;                             //记录上次随机数的数值，尽量避免产生几个相同的随机数
            Random rand = new Random();
            for (int i = 0; i < NumCount; i++)
            {
                if (temp != -1)
                {
                    rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
                }
                int t = rand.Next(35);
                if (temp == t)
                {
                    return CreateRandomNum(NumCount);
                }
                temp = t;
                randomNum += allCharArray[t];


            }
            return randomNum;
        }
        //生产图片
        private void CreateImage(string validateNum)
        {
            if (validateNum == null || validateNum.Trim() == string.Empty)
                return;
            //生成BitMap图像
            System.Drawing.Bitmap image = new System.Drawing.Bitmap(validateNum.Length * 12 + 12, 22);
            Graphics g = Graphics.FromImage(image);
            try
            {
                //生成随机生成器
                Random random = new Random();
                //清空图片背景
                g.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);
                    g.DrawLine(new Pen(Color.Silver), x1, x2, y1, y2);
                }
                Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.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);
                g.DrawString(validateNum, 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
                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
                System.IO.MemoryStream ms = new System.IO.MemoryStream();
                //将图像保存到指定流
                image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
                Response.ClearContent();
                Response.ContentType = "image/Gif";
                Response.BinaryWrite(ms.ToArray());
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }

View Code

4、运行效果

5、登陆的时候校验下页面中的输入内容和后台生成的 Session["ValidateNum"] 作校验

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原文地址：https://www.cnblogs.com/i-mengli/p/9723439.html