c#图片随机验证码的实现

来源：互联网发布：超图软件中标编辑：程序博客网时间：2024/05/02 02:35

新建Web窗体CheckCode.aspx

如下CheckCode.aspx.cs的代码：

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;
using System.Drawing.Design;

public partial class CheckCode : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        this.CreateCheckCodeImage(RndNum());
    }
    private string RndNum()
   {
       int number;
       char code;
       string checkcode = string.Empty;

System.Random random = new Random();

       for (int i = 0; i < 4; i++)
       {
           number = random.Next();
           if(number % 2== 0)
               code = (char)('0' + (char)(number % 10));

          else if(number % 3== 0)
               code = (char)('a' + (char)(number % 26));
           else
               code = (char)('A' + (char)(number % 26));
           checkcode += code.ToString();
       }
       Session["CheckCode"] = checkcode;
       return checkcode;
   }
   private void CreateCheckCodeImage(string checkcode)
   {
       if (checkcode == null || checkcode.Trim() == string.Empty)
           return;
       System.Drawing.Bitmap Image = new System.Drawing.Bitmap((int)Math.Ceiling((checkcode.Length*12.5)),22);
       Graphics G = Graphics.FromImage(Image);
       try
       {
           //生成随机生成器
           Random random = new Random();
           //清空图片背景色
           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,Y1,X2,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(checkcode,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();
           Image.Save(MS,System.Drawing.Imaging.ImageFormat.Gif);
           Response.ClearContent();
           Response.ContentType = "IMAGE/GIF";
           Response.BinaryWrite(MS.ToArray());
       }
       finally
       {
           G.Dispose();
           Image.Dispose();
       }
   }
}

然后在登录页面login.aspx中：

<asp:ImageButton ID="YZM" ImageUrl="~/checkcode.aspx" runat="server" Height="26px" Style="z-index: 101;
left: 143px; position: absolute; top: 65px" Width="57px" />
<asp:LinkButton ID="CHANGECODE" runat="server" onclick="CHANGECODE_CLICK" Style="z-index: 103; left: 141px;position: absolute; top: 99px" Font-Size="10pt" Width="81px">换一个验证码</asp:LinkButton>

<ASP:BUTTON ID="BUTTON1" RUNAT="SERVER" ONCLICK="BUTTON1_CLICK" TEXT="BUTTON" />

最后在login.aspx.cs中：

protected void CHANGECODE_CLICK(object sender, EventArgs e)
{

//什么都不用写

}

public void BUTTON1_CLICK(OBJECT SENDER, EVENTARGS E)
{
              if (Session["CheckCode"].ToString().ToLower() != TextBox.Text.ToLower())//忽略大小写
             {
                 //"验证码错误！
             }
             else
             {

//验证码正确
}

}