python - 如何解压缩字节数组中的 gzip 数据？

Question

我有一个字节数组，其中包含由 gzip 压缩的数据。现在我需要解压缩这些数据。如何实现？

Answer 1

zlib.decompress(data, 15 + 32) 应该自动检测您是否有 gzip 数据或 zlib 数据。

如果 gzip zlib.decompress(data, 15 + 16) 应该工作，如果 zlib 应该 barf。

这里是 Python 2.7.1，创建一个小 gz 文件，读回它，然后解压缩它:

>>> import gzip, zlib
>>> f = gzip.open('foo.gz', 'wb')
>>> f.write(b"hello world")
11
>>> f.close()
>>> c = open('foo.gz', 'rb').read()
>>> c
'\x1f\x8b\x08\x08\x14\xf4\xdcM\x02\xfffoo\x00\xcbH\xcd\xc9\xc9W(\xcf/\xcaI\x01\x00\x85\x11J\r\x0b\x00\x00\x00'
>>> ba = bytearray(c)
>>> ba
bytearray(b'\x1f\x8b\x08\x08\x14\xf4\xdcM\x02\xfffoo\x00\xcbH\xcd\xc9\xc9W(\xcf/\xcaI\x01\x00\x85\x11J\r\x0b\x00\x00\x00')
>>> zlib.decompress(ba, 15+32)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: must be string or read-only buffer, not bytearray
>>> zlib.decompress(bytes(ba), 15+32)
'hello world'
>>>

Python 3.x 的用法非常相似。

更新基于您正在运行 Python 2.2.1 的评论。

叹息。这甚至不是 Python 2.2 的最后一个版本。不管怎样，继续上面创建的 foo.gz 文件:

Python 2.2.3 (#42, May 30 2003, 18:12:08) [MSC 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> strobj = open('foo.gz', 'rb').read()
>>> strobj
'\x1f\x8b\x08\x08\x14\xf4\xdcM\x02\xfffoo\x00\xcbH\xcd\xc9\xc9W(\xcf/\xcaI\x01\x00\x85\x11J\r\x0b\x00\x00\x00'
>>> import zlib
>>> zlib.decompress(strobj, 15+32)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
zlib.error: Error -2 while preparing to decompress data
>>> zlib.decompress(strobj, 15+16)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
zlib.error: Error -2 while preparing to decompress data

# OK, we can't use the back door method. Plan B: use the 
# documented approach i.e. gzip.GzipFile with a file-like object.

>>> import gzip, cStringIO
>>> fileobj = cStringIO.StringIO(strobj)
>>> gzf = gzip.GzipFile('dummy-name', 'rb', 9, fileobj)
>>> gzf.read()
'hello world'

# Success. Now let's assume you have an array.array object-- which requires
# premeditation; they aren't created accidentally!
# The following code assumes subtype 'B' but should work for any subtype.

>>> import array, sys
>>> aaB = array.array('B')
>>> aaB.fromfile(open('foo.gz', 'rb'), sys.maxint)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
EOFError: not enough items in file
#### Don't panic, just read the fine manual
>>> aaB
array('B', [31, 139, 8, 8, 20, 244, 220, 77, 2, 255, 102, 111, 111, 0, 203, 72, 205, 201, 201, 87, 40, 207, 47, 202, 73, 1, 0, 133, 17, 74, 13, 11, 0, 0, 0])
>>> strobj2 = aaB.tostring()
>>> strobj2 == strobj
1 #### means True 
# You can make a str object and use that as above.

# ... or you can plug it directly into StringIO:
>>> gzip.GzipFile('dummy-name', 'rb', 9, cStringIO.StringIO(aaB)).read()
'hello world'