Timer_gdiplus.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Timer_GdiPlus.aspx.cs" Inherits="Timer_GdiPlus" %>
<%--<%@ Register Assembly="System.Web.Extensions, Version=2.0.50727, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
Namespace="System.Web.UI" TagPrefix="asp" %> --%>
<%--
<%@ Register Assembly="System.Web.Extensions, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
Namespace="System.Web.UI" TagPrefix="asp" %> --%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>未命名页面</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
</div>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<img id="imgTime" src="" runat="server" alt="a" />
</ContentTemplate>
</asp:UpdatePanel>
<asp:Timer ID="Timer1" runat="server" Interval="1000" OnTick="Timer1_Tick">
</asp:Timer>
</form>
</body>
</html>
timer_gdiplus.aspx.cs
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;
public partial class Timer_GdiPlus : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Timer1_Tick(object sender, EventArgs e)
{
imgTime.Visible = true;
imgTime.Src = "ImageHandler.ashx?" + DateTime.Now.Second; //1.这句话似懂非懂，给imgTime.Src赋值，那么DateTime.Now.Second又是干什么呢？“ImageHandler.ashx?" +“17：40：56”变成"ImageHandler.ashx?17：40：56"又是怎么起作用，怎样的流程呢？谢谢，这是第一个问题
}
}
ImageHandler.ashx内容
<%@ WebHandler Language="C#" Class="ImageHandler" %>
using System;
using System.Web;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;
public class ImageHandler : IHttpHandler {
public void ProcessRequest (HttpContext context) //2.这里的context是输入还是输出呢？
{
Bitmap imageTime = new Bitmap(500, 100);
Graphics g = Graphics.FromImage(imageTime);
SolidBrush colorPen = new SolidBrush(Color.White);
g.FillRectangle(colorPen, 0, 0, 500, 800);
Array obj = Enum.GetValues(typeof(HatchStyle));
int valueStyle = new Random().Next(obj.Length);
HatchStyle brushStyle = (HatchStyle)obj.GetValue(valueStyle);
HatchBrush theBrush = new HatchBrush(brushStyle, Color.White, Color.Black);
g.DrawString(DateTime.Now.ToLongTimeString(), new Font("Arial Black", 48), theBrush, 0, 0);
MemoryStream ms = new MemoryStream();
imageTime.Save(ms, System.Drawing.Imaging.ImageFormat.Bmp);
byte[] buffer = new byte[ms.Length];
ms.Seek(0, SeekOrigin.Begin); //3.这个Seek做啥用呢？
ms.Read(buffer, 0, (int)ms.Length);
ms.Close();
context.Response.OutputStream.Write(buffer, 0, buffer.Length);
context.Response.OutputStream.Close();
buffer = null;
imageTime.Dispose();
g.Dispose();
}
public bool IsReusable //4.这段代码干什么呢？
{
get
{
return false;
}
}
}
maiyude
