生成验证码，并进行验证（四位随机数字）

随机生成四位随机的验证码


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.Imaging;




public partial class Login : System.Web.UI.Page




...{


protected void Page_Load(object sender, EventArgs e)




...{


this.CreateCheckCodeImage(GenerateCheckCode());


if (!IsPostBack)




...{


BindMap();


}




}




protected void BindMap()




...{


Bitmap newBitmap = new Bitmap(36, 16, PixelFormat.Format32bppArgb);


Graphics g = Graphics.FromImage(newBitmap);


g.FillRectangle(new SolidBrush(Color.White), new Rectangle(0, 0, 36, 16));


Font textFont = new Font("Arail", 10);


RectangleF rectangle = new RectangleF(0, 0, 36, 16);


Random rd = new Random();


int valationNo = 1000 + rd.Next(8999);


Session.Remove("No");


Session.Add("No", valationNo);


g.FillRectangle(new SolidBrush(Color.BurlyWood), rectangle);


g.DrawString(valationNo.ToString(), textFont, new SolidBrush(Color.Blue), rectangle);


newBitmap.Save(Server.MapPath("imgs") + "/VaImag.gif", ImageFormat.Gif);




}


protected void ImageButton1_Click(object sender, ImageClickEventArgs e)




...{


//查看驗證碼欄位的驗證碼是否正確


if (validate.Text.Trim()!= Session["No"].ToString())




...{


BindMap();


Response.Write("<script language=javascript>alert('你輸入的驗證碼錯誤！');</script>");


}


else




...{


Response.Redirect("Default.htm");


}


}


}