这次在项目中，用到了大文件上传，要上传的文件有100多m，于是研究现在国内使用的大文件上传的
组件发现用的比较多的有两个控件AspnetUpload 2.0和Lion.Web.UpLoadModule，另外还有思归在它的博客
堂中所说的办法 http://blog.joycode.com/saucer/archive/2004/03/16/16225.aspx
   两个控件的方法是：利用隐含的HttpWorkerRequest，用它的GetPreloadedEntityBody 和 ReadEntityBody方法从IIS为ASP.NET建立的pipe里分块读取数据。Chris Hynes为我们提供了这样的一个方案(用HttpModule)，该方案除了允许你上传大文件外，还能实时显示上传进度。
    Lion.Web.UpLoadModule和AspnetUpload 两个.NET组件都是利用的这个方案。
   当上传单文件时，两个软件的方法是一样的，继承HttpModule
       HttpApplication application1 = sender as HttpApplication;
   HttpWorkerRequest request1 = (HttpWorkerRequest) ((IServiceProvider) HttpContext.Current).GetService(typeof(HttpWorkerRequest));
   try
   {
    if (application1.Context.Request.ContentType.IndexOf("multipart/form-data") <= -1)
    {
     return;
    }
    //Check The HasEntityBody
    if (!request1.HasEntityBody())
    {
     return;
    }

    int num1 = 0;
    TimeSpan span1 = DateTime.Now.Subtract(this.beginTime);

    string text1 = application1.Context.Request.ContentType.ToLower();

    byte[] buffer1 = Encoding.ASCII.GetBytes(("\r\n--" + text1.Substring(text1.IndexOf("boundary=") + 9)).ToCharArray());
    int num2 = Convert.ToInt32(request1.GetKnownRequestHeader(11));
    Progress progress1 = new Progress();

    application1.Context.Items.Add("FileList", new Hashtable());

    byte[] buffer2 = request1.GetPreloadedEntityBody();
    num1 += buffer2.Length;

    string text2 = this.AnalysePreloadedEntityBody(buffer2, "UploadGUID");
    if (text2 != string.Empty)
    {
     application1.Context.Items.Add("LionSky_UpLoadModule_UploadGUID", text2);
    }
    bool flag1 = true;
    if ((num2 > this.UpLoadFileLength()) && ((0 > span1.TotalHours) || (span1.TotalHours > 3)))
    {
     flag1 = false;
    }
    if ((0 > span1.TotalHours) || (span1.TotalHours > 3))
    {
     flag1 = false;
    }
    string text3 = this.AnalysePreloadedEntityBody(buffer2, "UploadFolder");
    ArrayList list1 = new ArrayList();
    RequestStream stream1 = new RequestStream(buffer2, buffer1, null, RequestStream.FileStatus.Close, RequestStream.ReadStatus.NoRead, text3, flag1, application1.Context, string.Empty);
    list1.AddRange(stream1.ReadBody);
    if (text2 != string.Empty)
    {
     progress1.FileLength = num2;
     progress1.ReceivedLength = num1;
     progress1.FileName = stream1.OriginalFileName;
     progress1.FileCount = ((Hashtable) application1.Context.Items["FileList"]).Count;
     application1.Application["_UploadGUID_" + text2] = progress1;
    }
    if (!request1.IsEntireEntityBodyIsPreloaded())
    {
     byte[] buffer4;
     ArrayList list2;
     int num3 = 204800;
     byte[] buffer3 = new byte[num3];
     while ((num2 - num1) >= n