asp.net GDI+绘制多个矩形

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.Drawing.Drawing2D;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        Bitmap bitmap = new Bitmap(360, 260);
        Graphics graphics = Graphics.FromImage(bitmap);
        graphics.Clear(Color.White);
        Pen pen = new Pen(Color.Blue, 2);
        Rectangle[] rects = { new Rectangle(10, 10, 20, 20), new Rectangle(100, 200, 250, 50), new Rectangle(300, 10, 50, 100) };
        graphics.DrawRectangles(pen, rects);
        System.IO.MemoryStream ms = new System.IO.MemoryStream();
        bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
        Response.ClearContent();
        Response.ContentType = "image/Jpeg";
        Response.BinaryWrite(ms.ToArray());
    }
}