验证码（转）

把下面代码存为一个文件code.aspx。另一个文件里调用<img src="code.aspx">


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;

public partial class Default4 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if(!Page.IsPostBack)
        {
            getimg(getcode(4));
        }
    }

    public string getcode(int num)
    {

        string[] source ={ "1", "A", "B", "4", "C", "6", "7", "8", "9", "Q", "W", "Y", "U", "O", "P" };
        //string[] source ={ "A", "B", "C", "Q", "W", "Y", "U", "O", "P" };
        string code = "";
        Random rm = new Random();
        for(int i = 0; i < num; i++)
        {
            code += source[rm.Next(0, source.Length)];
        }
        return code;
    }

    public void getimg(string code)
    {
        Bitmap myPalette = new Bitmap(60, 20);
        Graphics gh = Graphics.FromImage(myPalette);
        Rectangle rc = new Rectangle(0, 0, 60, 20);
        gh.FillRectangle(new SolidBrush(Color.Silver), rc);
        gh.DrawString(code, new Font("宋体", 16), new SolidBrush(Color.Gray), rc);
        myPalette.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
        Session["ValidataCode"] = code;
        gh.Dispose();
        myPalette.Dispose();

    }
}