从 FTP 服务器上的 gz 文件中检索数据而不在本地写入

2022-01-09 00:00:00 python gzip ftp ftplib

问题描述

我想检索存储在 FTP 服务器上的压缩 gz 文件中的数据，而不将文件写入本地存档.

I would like to retrieve the data inside a compressed gz file stored on an FTP server, without writing the file to the local archive.

目前我已经完成了

from ftplib import FTP
import gzip

ftp = FTP('ftp.server.com')
ftp.login()  
ftp.cwd('/a/folder/')

fileName = 'aFile.gz'

localfile = open(fileName,'wb')
ftp.retrbinary('RETR '+fileName, localfile.write, 1024)

f = gzip.open(localfile,'rb')
data = f.read()

然而，这会将文件localfile"写入当前存储.

This, however, writes the file "localfile" on the current storage.

我试图改变这个

from ftplib import FTP
import zlib

ftp = FTP('ftp.server.com')
ftp.login()  
ftp.cwd('/a/folder/')

fileName = 'aFile.gz'

data = ftp.retrbinary('RETR '+fileName, zlib.decompress, 1024)

但是，ftp.retrbinary 不输出其回调的输出.有没有办法做到这一点?

but, ftp.retrbinary does not output the output of its callback. Is there a way to do this?

解决方案

一个简单的实现是:

  • 将文件下载到内存中类似文件的对象，例如 BytesIO;

将其传递给 fileobj 参数noreferrer">GzipFile 构造函数.

pass that to fileobj parameter of GzipFile constructor.

import gzip
from io import BytesIO
import shutil
from ftplib import FTP

ftp = FTP('ftp.example.com')
ftp.login('username', 'password')

flo = BytesIO()

ftp.retrbinary('RETR /remote/path/archive.tar.gz', flo.write)

flo.seek(0)

with open('archive.tar', 'wb') as fout, gzip.GzipFile(fileobj = flo) as gzip:
    shutil.copyfileobj(gzip, fout)

<小时>

以上将整个 .gz 文件加载到内存中.对于大文件来说什么是低效的.更智能的实现将改为流式传输数据.但这可能需要实现一个智能的自定义类文件对象.

The above loads whole .gz file to a memory. What can be inefficient for large files. A smarter implementation would stream the data instead. But that would probably require implementing a smart custom file-like object.

另请参阅在 FTP 服务器上的 zip 文件中获取文件名，而无需下载整个存档.

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