python - 下载并解压内存中的gzip压缩文件？

Question

我想使用 urllib 下载一个文件并在保存之前解压缩内存中的文件。

这就是我现在所拥有的：

response = urllib2.urlopen(baseURL + filename)
compressedFile = StringIO.StringIO()
compressedFile.write(response.read())
decompressedFile = gzip.GzipFile(fileobj=compressedFile, mode='rb')
outfile = open(outFilePath, 'w')
outfile.write(decompressedFile.read())

这最终会写入空文件。我怎样才能实现我所追求的？

更新答案：

#! /usr/bin/env python2
import urllib2
import StringIO
import gzip

baseURL = "https://www.kernel.org/pub/linux/docs/man-pages/"        
# check filename: it may change over time, due to new updates
filename = "man-pages-5.00.tar.gz" 
outFilePath = filename[:-3]

response = urllib2.urlopen(baseURL + filename)
compressedFile = StringIO.StringIO(response.read())
decompressedFile = gzip.GzipFile(fileobj=compressedFile)

with open(outFilePath, 'w') as outfile:
    outfile.write(decompressedFile.read())

Answer 1

您需要compressedFile在写入之后但在将其传递给gzip.GzipFile(). 否则它将被gzip模块从末尾读取，并显示为一个空文件。见下文：

#! /usr/bin/env python
import urllib2
import StringIO
import gzip

baseURL = "https://www.kernel.org/pub/linux/docs/man-pages/"
filename = "man-pages-3.34.tar.gz"
outFilePath = "man-pages-3.34.tar"

response = urllib2.urlopen(baseURL + filename)
compressedFile = StringIO.StringIO()
compressedFile.write(response.read())
#
# Set the file's current position to the beginning
# of the file so that gzip.GzipFile can read
# its contents from the top.
#
compressedFile.seek(0)

decompressedFile = gzip.GzipFile(fileobj=compressedFile, mode='rb')

with open(outFilePath, 'w') as outfile:
    outfile.write(decompressedFile.read())

Answer 2

对于那些使用 Python 3 的人来说，等价的答案是：

import urllib.request
import io
import gzip

response = urllib.request.urlopen(FILE_URL)
compressed_file = io.BytesIO(response.read())
decompressed_file = gzip.GzipFile(fileobj=compressed_file)

with open(OUTFILE_PATH, 'wb') as outfile:
    outfile.write(decompressed_file.read())

Answer 3

如果你有 Python 3.2 或更高版本，生活会容易得多：

#!/usr/bin/env python3
import gzip
import urllib.request

baseURL = "https://www.kernel.org/pub/linux/docs/man-pages/"
filename = "man-pages-4.03.tar.gz"
outFilePath = filename[:-3]

response = urllib.request.urlopen(baseURL + filename)
with open(outFilePath, 'wb') as outfile:
    outfile.write(gzip.decompress(response.read()))

对于那些对历史感兴趣的人，请参阅https://bugs.python.org/issue3488和https://hg.python.org/cpython/rev/3fa0a9553402。

Answer 4

一行代码打印解压后的文件内容：

print gzip.GzipFile(fileobj=StringIO.StringIO(urllib2.urlopen(DOWNLOAD_LINK).read()), mode='rb').read()