12.2. gzip
— 对 gzip 格式的支持¶
源代码: Lib/gzip.py
此模块提供的简单接口帮助用户压缩和解压缩文件,功能类似于 GNU 应用程序 gzip 和 gunzip。
数据压缩由 zlib
模块提供。
The gzip
module provides the GzipFile
class which is modeled
after Python’s File Object. The GzipFile
class reads and writes
gzip-format files, automatically compressing or decompressing the
data so that it looks like an ordinary file object.
注意,此模块不支持部分可以被 gzip 和 gunzip 解压的格式,如利用 compress 或 pack 压缩所得的文件。
这个模块定义了以下内容:
-
class
gzip.
GzipFile
([filename[, mode[, compresslevel[, fileobj[, mtime]]]]])¶ Constructor for the
GzipFile
class, which simulates most of the methods of a file object, with the exception of thereadinto()
andtruncate()
methods. 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, a
StringIO
object, or any other object which simulates a file. It defaults toNone
, in which case filename is opened to provide a file object.当 fileobj 为
None
时, filename 参数只用于 gzip 文件头中,这个文件有可能包含未压缩文件的源文件名。如果文件可以被识别,默认 fileobj 的文件名;否则默认为空字符串,在这种情况下文件头将不包含源文件名。The mode argument can be any of
'r'
,'rb'
,'a'
,'ab'
,'w'
, or'wb'
, depending on whether the file will be read or written. The default is the mode of fileobj if discernible; otherwise, the default is'rb'
. If not given, the ‘b’ flag will be added to the mode to ensure the file is opened in binary mode for cross-platform portability.compresslevel 参数是一个从
0
to9
的整数,用于控制压缩等级;1
最快但压缩比例最小,9
最慢但压缩比例最大。0
不压缩。默认为9
。The mtime argument is an optional numeric timestamp to be written to the stream when compressing. All gzip compressed streams are required to contain a timestamp. If omitted or
None
, the current time is used. This module ignores the timestamp when decompressing; however, some programs, such as gunzip, make use of it. The format of the timestamp is the same as that of the return value oftime.time()
and of thest_mtime
attribute of the object returned byos.stat()
.Calling a
GzipFile
object’sclose()
method does not close fileobj, since you might wish to append more material after the compressed data. This also allows you to pass aStringIO
object opened for writing as fileobj, and retrieve the resulting memory buffer using theStringIO
object’sgetvalue()
method.GzipFile
supports iteration and thewith
statement.在 2.7 版更改: Support for the
with
statement was added.在 2.7 版更改: Support for zero-padded files was added.
2.7 新版功能: The mtime argument.
-
gzip.
open
(filename[, mode[, compresslevel]])¶ This is a shorthand for
GzipFile(filename,
mode,
compresslevel)
. The filename argument is required; mode defaults to'rb'
and compresslevel defaults to9
.
12.2.1. 用法示例¶
读取压缩文件示例:
import gzip
with gzip.open('file.txt.gz', 'rb') as f:
file_content = f.read()
创建GZIP 文件示例:
import gzip
content = "Lots of content here"
with gzip.open('file.txt.gz', 'wb') as f:
f.write(content)
使用 GZIP 压缩已有的文件示例:
import gzip
import shutil
with open('file.txt', 'rb') as f_in, gzip.open('file.txt.gz', 'wb') as f_out:
shutil.copyfileobj(f_in, f_out)
参见
- 模块
zlib
支持 gzip 格式所需要的基本压缩模块。