我试图通过一个打开的连接将多个文件下载到内存中。
我从本文档中知道:https://docs.microsoft.com/en-us/dotnet/api/system.net.ftpwebrequest.keepalive – FtpWebRequest
默认将KeepAlive
设置为true。
如果与服务器的连接不应被破坏;否则为假。默认值为true。
我创建了这段代码:
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
namespace ConsoleApp23
{
class Program
{
static void Main(string[] args)
{
String[] files = FTPListTree("ftp://server.com", "user", "password");
for (int i = 0; i <= files.Count() - 1; i++)
{
string path = files[i].ToString();
var request = (FtpWebRequest)WebRequest.Create(path);
request.Method = WebRequestMethods.Ftp.DownloadFile;
request.Credentials = new NetworkCredential("user", "password");
request.Timeout = 100000;
request.KeepAlive = true;
request.ConnectionGroupName = "DownloadFilesGroup";
request.ServicePoint.ConnectionLimit = 8;
using (var response = (FtpWebResponse)request.GetResponse())
{
using (var stream = response.GetResponseStream())
{
var ms = new MemoryStream();
stream.CopyTo(ms);
var a = ms.ToArray();
string ss = Encoding.UTF8.GetString(a);
Console.WriteLine(ss);
}
}
}
}
public static String[] FTPListTree(String ftpUri, String user, String pass)
{
try
{
List<String> files = new List<String>();
Queue<String> folders = new Queue<String>();
folders.Enqueue(ftpUri);
while (folders.Count > 0)
{
String fld = folders.Dequeue();
List<String> newFiles = new List<String>();
FtpWebRequest ftp = (FtpWebRequest)FtpWebRequest.Create(fld);
ftp.Timeout = 20000;
ftp.Credentials = new NetworkCredential(user, pass);
ftp.Method = WebRequestMethods.Ftp.ListDirectory;
using (StreamReader resp = new StreamReader(ftp.GetResponse().GetResponseStream()))
{
String line = resp.ReadLine();
while (line != null)
{
newFiles.Add(line.Trim());
line = resp.ReadLine();
}
}
ftp = (FtpWebRequest)FtpWebRequest.Create(fld);
ftp.Timeout = 20000;
ftp.Credentials = new NetworkCredential(user, pass);
ftp.Method = WebRequestMethods.Ftp.ListDirectory;
using (StreamReader resp = new StreamReader(ftp.GetResponse().GetResponseStream()))
{
String line = resp.ReadLine();
while (line != null)
{
if (!Path.HasExtension(line))
{
String dir = newFiles.First(x => line.EndsWith(x));
newFiles.Remove(dir);
folders.Enqueue(fld + dir + "/");
}
line = resp.ReadLine();
}
}
files.AddRange(from f in newFiles select fld + f);
}
return files.ToArray();
}
catch (Exception e)
{
throw;
}
}
}
}
这是处置的正确方法吗?我似乎找不到任何有关处置response
或响应流是否会关闭控件连接,keepalive保持打开状态的文档。
运行此程序时,有什么方法可以记录此消息,以便可以看到FTP调用?我本人无权访问FTP服务器。
UPDATE
我实际上已经使用测试FTP和上面的代码对此进行了测试,即使它具有KeepAlive=true
,它也会在每个请求上使用新的连接。我已经使用Fluent API创建了PoC:https://github.com/robinrodricks/FluentFTP/blob/master/FluentFTP.CSharpExamples/DownloadManyFiles.cs,它可以正确执行此操作:连接一次并下载文件。我觉得FtpWebRequest
就是这种情况。我不了解KeepAlive
及其功能。也许它重用了TCP连接,这本身就是一件好事,但是它使用TCP连接来登录每个请求。
有人知道是否甚至可以通过FtpWebRequest
而不是登录每个新请求(例如Fluent FTP API)吗?我想念什么吗?
FTP是FileZilla Server 0.9.60 beta。
似乎在.NET Core中未实现FTP连接重用:https://github.com/dotnet/runtime/issues/23256
而且作为*WebRequest
API is actually obsolete,它可能永远也不会。
使用.NET框架,它可以按预期工作:*WebRequest