using System;
using System.Data;
using System.Configuration;
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.Text;
using System.IO;

/**//// ＜summary＞
/// Summary description for HtmlProxy
/// ＜/summary＞
public class HtmlProxy
...{
public HtmlProxy()
...{
}
public static bool ChangeFile(int id)
...{
string filename = HttpContext.Current.Server.MapPath("Post_" + id + ".html");
//尝试读取已有文件
Stream st = GetFileStream(filename);
//如果文件存在并且读取成功
if (st != null)
...{
using (st)
...{
StreamToStream(st, HttpContext.Current.Response.OutputStream);
return true;
//Response.End();
}
}
else
...{
StringWriter sw = new StringWriter();
HttpContext.Current.Server.Execute("ForumDetail.aspx?PID=" + id, sw);

string content = sw.ToString();
//写进文件
try
...{
using (FileStream fs = new FileStream(filename, FileMode.Create, FileAccess.Write, FileShare.Write))
...{
using (StreamWriter stw = new StreamWriter(fs, HttpContext.Current.Response.ContentEncoding))
...{
stw.Write(content);
}
}
　return true;
}
catch ...{ return false; }
}
}

private static Stream GetFileStream(string filename)
...{
try
...{
DateTime dt = File.GetLastWriteTime(filename);
TimeSpan ts = dt - DateTime.Now;
if (ts.TotalHours ＞1)
...{
//一小时后过期
return null;
}
return new FileStream(filename, FileMode.Open, FileAccess.Read, FileShare.Read);
}
catch ...{ return null; }
}
static public void StreamToStream(Stream src, Stream dst)
...{
　　byte[] buf = new byte[4096];
　　while (true)
...{
int c = src.Read(buf, 0, buf.Length);
if (c == 0)
return;
dst.Write(buf, 0, c);
　}
　}
}
　　在页面文件中，ForURL.aspx的后台代码如下：
protected void Page_Load(object sender, EventArgs e)
...{
try
...{
int id = int.Parse(Request.QueryString["PID"]);
if(HtmlProxy.ChangeFile(id))
...{
　Response.Redirect("Post_" + id + ".html");
}
　else
...{
　Response.Redirect("Post.aspx?PID=" + id );
}
}
　catch ...{
}
}