我以前做过。首先，很明显，文件必须位于网站用户进程可以访问的外部服务器上的共享中。
就 HTTPHandler 而言，我通过为用户提供包含他们想要下载的文件的 zip 文件来处理这个问题；这样，我的处理程序就可以拦截对 .zip 文件的任何调用，并将它们流式传输到我创建的 zip 文件中。
这是代码（相当大的一部分；我使用 MVP，所以它分为 Handler 和 Presenter）：
处理程序：
public class ZipDownloadModule: IHttpHandler, ICompressFilesView, IErrorView
{
CompressFilesPresenter _presenter;
public ZipDownloadModule()
{
_presenter = new CompressFilesPresenter(this, this);
}
#region IHttpHandler Members
public bool IsReusable
{
get { return true; }
}
public void ProcessRequest(HttpContext context)
{
OnDownloadFiles();
}
private void OnDownloadFiles()
{
if(Compress != null)
Compress(this, EventArgs.Empty);
}
#endregion
#region IFileListDownloadView Members
public IEnumerable<string> FileNames
{
get
{
string files = HttpContext.Current.Request["files"] ?? string.Empty;
return files.Split(new Char[] { ',' });
}
}
public System.IO.Stream Stream
{
get
{
HttpContext.Current.Response.ContentType = "application/x-zip-compressed";
HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment; filename=ads.zip");
return HttpContext.Current.Response.OutputStream;
}
}
public event EventHandler Compress;
#endregion
#region IErrorView Members
public string errorMessage
{
set { }
}
#endregion
}
演讲者：
public class CompressFilesPresenter: PresenterBase<ICompressFilesView>
{
IErrorView _errorView;
public CompressFilesPresenter(ICompressFilesView view, IErrorView errorView)
: base(view)
{
_errorView = errorView;
this.View.Compress += new EventHandler(View_Compress);
}
void View_Compress(object sender, EventArgs e)
{
CreateZipFile();
}
private void CreateZipFile()
{
MemoryStream stream = new MemoryStream();
try
{
CreateZip(stream, this.View.FileNames);
WriteZip(stream);
}
catch(Exception ex)
{
HandleException(ex);
}
}
private void WriteZip(MemoryStream stream)
{
byte[] data = stream.ToArray();
this.View.Stream.Write(data, 0, data.Length);
}
private void CreateZip(MemoryStream stream, IEnumerable<string> filePaths)
{
using(ZipOutputStream s = new ZipOutputStream(stream)) // this.View.Stream))
{
s.SetLevel(9); // 0 = store only to 9 = best compression
foreach(string fullPath in filePaths)
AddFileToZip(fullPath, s);
s.Finish();
}
}
private static void AddFileToZip(string fullPath, ZipOutputStream s)
{
byte[] buffer = new byte[4096];
ZipEntry entry;
// Using GetFileName makes the result compatible with XP
entry = new ZipEntry(Path.GetFileName(fullPath));
entry.DateTime = DateTime.Now;
s.PutNextEntry(entry);
using(FileStream fs = File.OpenRead(fullPath))
{
int sourceBytes;
do
{
sourceBytes = fs.Read(buffer, 0, buffer.Length);
s.Write(buffer, 0, sourceBytes);
} while(sourceBytes > 0);
}
}
private void HandleException(Exception ex)
{
switch(ex.GetType().ToString())
{
case "DirectoryNotFoundException":
_errorView.errorMessage = "The expected directory does not exist.";
break;
case "FileNotFoundException":
_errorView.errorMessage = "The expected file does not exist.";
break;
default:
_errorView.errorMessage = "There has been an error. If this continues please contact AMG IT Support.";
break;
}
}
private void ClearError()
{
_errorView.errorMessage = "";
}
}
希望这会有所帮助！