验证码

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

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        System.Drawing.Image img = new Bitmap(200, 60);
        Graphics g = Graphics.FromImage(img);
        this.dealimage(img, 2000);
        g.DrawLine(Pens.Red, 0, 0, 200, 60);
        string code = this.GenerateCode();
        Font font = new Font("宋体", 24, FontStyle.Bold | FontStyle.Italic | FontStyle.Strikeout);
        g.DrawString(code, font, Brushes.GreenYellow, 10, 10);

        this.Response.Clear();
        MemoryStream ms = new MemoryStream();
        img.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
        this.Response.BinaryWrite(ms.ToArray());
        this.Response.Flush();
        this.Response.End();

    }
    private void dealimage(System.Drawing.Image img, int nums)
    {
        Bitmap b = img as Bitmap;
        Random ran = new Random();
        for (int i = 0; i < nums; i++)
        {
            b.SetPixel(ran.Next(0, img.Width), ran.Next(0, img.Height), Color.White);
        }
    }


    private string GenerateCode()
    {
        Random ran = new Random(DateTime.Now.Millisecond);
        StringBuilder sb = new StringBuilder(6);
        for (int i = 0; i < 6; i++)
        {
            sb.Append(ran.Next(0, 9));
        }
        return sb.ToString();

    }
}