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c# - 列出位于 C# 中 SFTP 服务器上的 ZIP 文件中的文件

问题描述

我需要通过 ASP.NET Core 以编程方式处理来自 SFTP 服务器 (WinSCP) 的 ZIP 文件中的文件夹。

有什么方法可以在不下载到本地计算机的情况下获取 ZIP 文件中的文件列表？因为文件大小会很高并且不会以一致的方式。任何帮助，将不胜感激。

标签： c#.netasp.net-coresftpwinscp

解决方案

使用SSH.NET 库，它可以很简单：

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);
        }
    }
}

您需要参考System.IO.Compression程序集来获取ZipArchive.

该代码将仅读取（下载）ZIP 中央目录记录，而不是整个 ZIP 存档。有关证明，请参见答案的末尾。

不幸的是，库中有一个错误。要解决它，您必须Stream像这样实现包装器实现：

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;
}

并将其包装SftpFileStream起来：

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

为了证明它确实有效，我已将日志记录添加到FixStream. 当使用包含两个条目的 18 MB（18265315 字节）ZIP 存档的代码时，会生成以下内容。所以只从流中读取了 244 个字节。实际上更多是从实际的远程 SFTP 文件中读取的，因为 SSH.NET 会缓冲读取（否则代码将非常无效，特别是在这种情况下，正如您所看到的那样，ZipArchive它会进行大量的小读取）。默认 SSH.NET 缓冲区为 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

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