列出位於 C# 中 SFTP 服務器上的 ZIP 文件中的文件

Question

我需要通過 ASP.NET Core 以編程方式處理來自 SFTP 服務器 (WinSCP) 的 ZIP 文件中的文件夾。

有什么方法可以在不下載到本地計算機的情況下獲取 ZIP 文件中的文件列表？ 由於文件大小會很大並且不會以一致的方式。 任何幫助，將不勝感激。

Answer 1

使用SSH.NET 庫，它可以很簡單：

using (var client = new SftpClient(host, username, password)
{
    client.Connect();

    using (Stream stream = client.OpenRead("/remote/path/archive.zip"))
    using (var archive = new ZipArchive(stream, ZipArchiveMode.Read))
    {
        foreach (var entry in archive.Entries)
        {
            Console.WriteLine(entry);
        }
    }
}

您需要引用System.IO.Compression程序集來獲取ZipArchive 。

該代碼只會讀取（下載）ZIP 中央目錄記錄，而不是整個 ZIP 檔案。 有關證明，請參閱答案的末尾。

---

不幸的是，庫中有一個錯誤。 要解決它，您必須像這樣實現包裝器Stream實現：

class FixStream : Stream
{
    public override long Seek(long offset, SeekOrigin origin)
    {
        long result;
        // workaround for SSH.NET bug in implementation of SeekOrigin.End
        if (origin == SeekOrigin.End)
        {
            result = _stream.Seek(Length + offset, SeekOrigin.Begin);
        }
        else
        {
            result = _stream.Seek(offset, origin);
        }
        return result;
    }

    // passthrough implementation of the rest of Stream interface

    public override bool CanRead => _stream.CanRead;

    public override bool CanSeek => _stream.CanSeek;

    public override bool CanWrite => _stream.CanWrite;

    public override long Length => _stream.Length;

    public override long Position { 
        get => _stream.Position; set => _stream.Position = value; }

    public FixStream(Stream stream)
    {
        _stream = stream;
    }

    public override void Flush()
    {
        _stream.Flush();
    }

    public override int Read(byte[] buffer, int offset, int count)
    {
        return _stream.Read(buffer, offset, count);
    }

    public override void SetLength(long value)
    {
        _stream.SetLength(value);
    }

    public override void Write(byte[] buffer, int offset, int count)
    {
        _stream.Write(buffer, offset, count);
    }

    private Stream _stream;
}

並將SftpFileStream包裝到它：

using (Stream stream = client.OpenRead("/remote/path/archive.zip"))
using (var stream2 = new FixStream(stream))
using (var archive = new ZipArchive(stream2, ZipArchiveMode.Read))
{
    ...
}

---

作為它確實有效的證明，我已將日志記錄添加到FixStream的所有方法。 當使用帶有兩個條目的 18 MB（18265315 字節）ZIP 存檔的代碼時，生成了以下內容。 所以從 stream 中只讀取了 244 個字節。實際上更多的是從實際的遠程 SFTP 文件中讀取，因為 SSH.NET 緩沖讀取（否則代碼將非常無效，特別是在這種情況下，正如您所看到的ZipArchive做很多小讀）。 默認的 SSH.NET 緩沖區是 32 KB ( SftpClient.BufferSize )。

Tried to seek to -18 from End => converting to seek to 18265297 from Begin
Seeked to 18265297 from Begin => 18265297
Seeked to -32 from Current => 18265265
Tried to read 32, got 32
Seeked to -32 from Current => 18265265
Seeked to 28 from Current => 18265293
Tried to read 4, got 4
Tried to read 2, got 2
Tried to read 2, got 2
Tried to read 2, got 2
Tried to read 2, got 2
Tried to read 4, got 4
Tried to read 4, got 4
Tried to read 2, got 2
Seeked to 18265075 from Begin => 18265075
Tried to read 4, got 4
Tried to read 1, got 1
Tried to read 1, got 1
Tried to read 2, got 2
Tried to read 2, got 2
Tried to read 2, got 2
Tried to read 4, got 4
Tried to read 4, got 4
Tried to read 4, got 4
Tried to read 4, got 4
Tried to read 2, got 2
Tried to read 2, got 2
Tried to read 2, got 2
Tried to read 2, got 2
Tried to read 2, got 2
Tried to read 4, got 4
Tried to read 4, got 4
Tried to read 28, got 28
Tried to read 2, got 2
Tried to read 2, got 2
Tried to read 32, got 32
Set position to 18265185
Tried to read 4, got 4
Tried to read 1, got 1
Tried to read 1, got 1
Tried to read 2, got 2
Tried to read 2, got 2
Tried to read 2, got 2
Tried to read 4, got 4
Tried to read 4, got 4
Tried to read 4, got 4
Tried to read 4, got 4
Tried to read 2, got 2
Tried to read 2, got 2
Tried to read 2, got 2
Tried to read 2, got 2
Tried to read 2, got 2
Tried to read 4, got 4
Tried to read 4, got 4
Tried to read 26, got 26
Tried to read 2, got 2
Tried to read 2, got 2
Tried to read 32, got 32
Set position to 18265293
Tried to read 4, got 4