13.2. gzip — 支持 gzip 文件 ¶

源代码： Lib/gzip.py

This module provides a simple interface to compress and decompress files just like the GNU programs gzip and gunzip would.

The data compression is provided by the zlib 模块。

gzip module provides the GzipFile class, as well as the open() , compress() and decompress() convenience functions. GzipFile class reads and writes gzip -format files, automatically compressing or decompressing the data so that it looks like an ordinary 文件对象 .

Note that additional file formats which can be decompressed by the gzip and gunzip programs, such as those produced by compress and pack , are not supported by this module.

模块定义了下列项：

gzip. open ( filename , mode='rb' , compresslevel=9 , encoding=None , errors=None , newline=None ) ¶

Open a gzip-compressed file in binary or text mode, returning a 文件对象 .

filename argument can be an actual filename (a str or bytes object), or an existing file object to read from or write to.

mode argument can be any of 'r' , 'rb' , 'a' , 'ab' , 'w' , 'wb' , 'x' or 'xb' for binary mode, or 'rt' , 'at' , 'wt' ，或 'xt' for text mode. The default is 'rb' .

compresslevel argument is an integer from 0 to 9, as for the GzipFile 构造函数。

For binary mode, this function is equivalent to the GzipFile 构造函数： GzipFile(filename, 模式， compresslevel) . In this case, the encoding , errors and newline arguments must not be provided.

For text mode, a GzipFile object is created, and wrapped in an io.TextIOWrapper instance with the specified encoding, error handling behavior, and line ending(s).

3.3 版改变： 添加支持 filename being a file object, support for text mode, and the encoding , errors and newline 自变量。

3.4 版改变： 添加支持 'x' , 'xb' and 'xt' 模式。

3.6 版改变： 接受 像路径对象 .

class gzip. GzipFile ( filename=None , mode=None , compresslevel=9 , fileobj=None , mtime=None ) ¶

Constructor for the GzipFile class, which simulates most of the methods of a 文件对象 , with the exception of the truncate() method. At least one of fileobj and filename must be given a non-trivial value.

The new class instance is based on fileobj , which can be a regular file, an io.BytesIO object, or any other object which simulates a file. It defaults to None , in which case filename is opened to provide a file object.

当 fileobj 不是 None ， filename argument is only used to be included in the gzip file header, which may include the original filename of the uncompressed file. It defaults to the filename of fileobj , if discernible; otherwise, it defaults to the empty string, and in this case the original filename is not included in the header.

mode argument can be any of 'r' , 'rb' , 'a' , 'ab' , 'w' , 'wb' , 'x' ，或 'xb' , depending on whether the file will be read or written. The default is the mode of fileobj if discernible; otherwise, the default is 'rb' .

Note that the file is always opened in binary mode. To open a compressed file in text mode, use open() (or wrap your GzipFile with an io.TextIOWrapper ).

compresslevel argument is an integer from 0 to 9 controlling the level of compression; 1 is fastest and produces the least compression, and 9 is slowest and produces the most compression. 0 is no compression. The default is 9 .

mtime argument is an optional numeric timestamp to be written to the last modification time field in the stream when compressing. It should only be provided in compression mode. If omitted or None , the current time is used. See the mtime attribute for more details.

Calling a GzipFile object’s close() method does not close fileobj , since you might wish to append more material after the compressed data. This also allows you to pass an io.BytesIO object opened for writing as fileobj , and retrieve the resulting memory buffer using the io.BytesIO object’s getvalue() 方法。

GzipFile 支持 io.BufferedIOBase interface, including iteration and the with statement. Only the truncate() method isn’t implemented.

GzipFile also provides the following method and attribute:

peek ( n ) ¶

Read n uncompressed bytes without advancing the file position. At most one single read on the compressed stream is done to satisfy the call. The number of bytes returned may be more or less than requested.

注意

While calling peek() does not change the file position of the GzipFile , it may change the position of the underlying file object (e.g. if the GzipFile was constructed with the fileobj parameter).

3.2 版新增。

mtime ¶

When decompressing, the value of the last modification time field in the most recently read header may be read from this attribute, as an integer. The initial value before reading any headers is None .

所有 gzip compressed streams are required to contain this timestamp field. Some programs, such as gunzip , make use of the timestamp. The format is the same as the return value of time.time() 和 st_mtime attribute of the object returned by os.stat() .

3.1 版改变： 支持 with statement was added, along with the mtime constructor argument and mtime 属性。

3.2 版改变： Support for zero-padded and unseekable files was added.

3.3 版改变： io.BufferedIOBase.read1() method is now implemented.

3.4 版改变： 添加支持 'x' and 'xb' 模式。

3.5 版改变： Added support for writing arbitrary 像字节对象 . read() method now accepts an argument of None .

3.6 版改变： 接受 像路径对象 .

gzip. compress ( data , compresslevel=9 ) ¶

Compress the data , returning a bytes object containing the compressed data. compresslevel has the same meaning as in the GzipFile constructor above.

3.2 版新增。

gzip. decompress ( data ) ¶

Decompress the data , returning a bytes object containing the uncompressed data.

3.2 版新增。

import gzip
with gzip.open('/home/joe/file.txt.gz', 'rb') as f:
    file_content = f.read()
								

import gzip
content = b"Lots of content here"
with gzip.open('/home/joe/file.txt.gz', 'wb') as f:
    f.write(content)
								

import gzip
import shutil
with open('/home/joe/file.txt', 'rb') as f_in:
    with gzip.open('/home/joe/file.txt.gz', 'wb') as f_out:
        shutil.copyfileobj(f_in, f_out)
								

import gzip
s_in = b"Lots of content here"
s_out = gzip.compress(s_in)
								

内容表

• 13.2. gzip — 支持 gzip 文件
  • 13.2.1. Examples of usage

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