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  • .net 点击刷新验证码问题

    验证码生成文件:validate.aspx.cs

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

    public partial class validate : System.Web.UI.Page
    {
        
    private Bitmap validateimage;
        
    private Graphics g;
        
    protected void Page_Load(object sender, EventArgs e)
        
    {

            
    if (!IsPostBack)
            
    {

                
    string VNum = MakeValidateCode();
                Session[
    "VNum"= VNum;
                ValidateCode(VNum);

            }

        }




        
    public void ValidateCode(string VNum)
        
    {
            validateimage 
    = new Bitmap(6015, PixelFormat.Format24bppRgb);
            g 
    = Graphics.FromImage(validateimage);


            g.FillRectangle(
    new LinearGradientBrush(new Point(00), new Point(11020), Color.FromArgb(240255255255), Color.FromArgb(240255255255)), 00200200);
            g.DrawString(VNum, 
    new Font("arial"11), new SolidBrush(Color.Red), new PointF(60));
            g.Save();
            MemoryStream ms 
    = new MemoryStream();
            validateimage.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
            Response.ClearContent();
            Response.ContentType 
    = "image/bmp";
            Response.BinaryWrite(ms.ToArray());
            Response.End();
        }


        
    string MakeValidateCode()
        
    {
            
    char[] s = new char[]{'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','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 num = "";
            Random r 
    = new Random();
            
    for (int i = 0; i < 4; i++)
            
    {
                num 
    += s[r.Next(0, s.Length)].ToString();
            }

            
    return num;
        }

    }


    在页面中调用:
    <img src="../validate.aspx" id="yzm" onclick="this.src='../validate.aspx?abc='+Math.random()" alt="图片看不清?点击重新得到验证码" style="cursor:hand;" />
    注意:有一点要说明,当点击刷新时,validate.asp?后面一定要有一个参数,若没有这个无效的参数,程序会认为你请求的是同一个文件,因而不会刷新的。这里的参数abc是个随意的,只起改变请求文件的作用。
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  • 原文地址:https://www.cnblogs.com/wbcms/p/1043769.html
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