class file(object)

    def close(self): # real signature unknown; restored from __doc__

        关闭文件

        """

        close() -> None or (perhaps) an integer.  Close the file.

        Sets data attribute .closed to True.  A closed file cannot be used for

        further I/O operations.  close() may be called more than once without

        error.  Some kinds of file objects (for example, opened by popen())

        may return an exit status upon closing.

        """

    def fileno(self): # real signature unknown; restored from __doc__

        文件描述符

         """

        fileno() -> integer "file descriptor".

        This is needed for lower-level file interfaces, such os.read().

        """

        return 0    

    def flush(self): # real signature unknown; restored from __doc__

        刷新文件内部缓冲区

        """ flush() -> None.  Flush the internal I/O buffer. """

        pass

    def isatty(self): # real signature unknown; restored from __doc__

        判断文件是否是同意tty设备

        """ isatty() -> true or false.  True if the file is connected to a tty device. """

        return False

    def next(self): # real signature unknown; restored from __doc__

        获取下一行数据，不存在，则报错

        """ x.next() -> the next value, or raise StopIteration """

        pass

    def read(self, size=None): # real signature unknown; restored from __doc__

        读取指定字节数据

        """

        read([size]) -> read at most size bytes, returned as a string.

        If the size argument is negative or omitted, read until EOF is reached.

        Notice that when in non-blocking mode, less data than what was requested

        may be returned, even if no size parameter was given.

        """

        pass

    def readinto(self): # real signature unknown; restored from __doc__

        读取到缓冲区，不要用，将被遗弃

        """ readinto() -> Undocumented.  Don't use this; it may go away. """

        pass

    def readline(self, size=None): # real signature unknown; restored from __doc__

        仅读取一行数据

        """

        readline([size]) -> next line from the file, as a string.

        Retain newline.  A non-negative size argument limits the maximum

        number of bytes to return (an incomplete line may be returned then).

        Return an empty string at EOF.

        """

        pass

    def readlines(self, size=None): # real signature unknown; restored from __doc__

        读取所有数据，并根据换行保存值列表

        """

        readlines([size]) -> list of strings, each a line from the file.

        Call readline() repeatedly and return a list of the lines so read.

        The optional size argument, if given, is an approximate bound on the

        total number of bytes in the lines returned.

        """

        return []

    def seek(self, offset, whence=None): # real signature unknown; restored from __doc__

        指定文件中指针位置

        """

        seek(offset[, whence]) -> None.  Move to new file position.

        Argument offset is a byte count.  Optional argument whence defaults to

(offset from start of file, offset should be >= 0); other values are 1

        (move relative to current position, positive or negative), and 2 (move

        relative to end of file, usually negative, although many platforms allow

        seeking beyond the end of a file).  If the file is opened in text mode,

        only offsets returned by tell() are legal.  Use of other offsets causes

        undefined behavior.

        Note that not all file objects are seekable.

        """

        pass

    def tell(self): # real signature unknown; restored from __doc__

        获取当前指针位置

        """ tell() -> current file position, an integer (may be a long integer). """

        pass

    def truncate(self, size=None): # real signature unknown; restored from __doc__

        截断数据，仅保留指定之前数据

        """

        truncate([size]) -> None.  Truncate the file to at most size bytes.

        Size defaults to the current file position, as returned by tell().

        """

        pass

    def write(self, p_str): # real signature unknown; restored from __doc__

        写内容

        """

        write(str) -> None.  Write string str to file.

        Note that due to buffering, flush() or close() may be needed before

        the file on disk reflects the data written.

        """

        pass

    def writelines(self, sequence_of_strings): # real signature unknown; restored from __doc__

        将一个字符串列表写入文件

        """

        writelines(sequence_of_strings) -> None.  Write the strings to the file.

        Note that newlines are not added.  The sequence can be any iterable object

        producing strings. This is equivalent to calling write() for each string.

        """

        pass

    def xreadlines(self): # real signature unknown; restored from __doc__

        可用于逐行读取文件，非全部

        """

        xreadlines() -> returns self.

        For backward compatibility. File objects now include the performance

        optimizations previously implemented in the xreadlines module.

        """

        pass

2.x

class TextIOWrapper(_TextIOBase):

    """

    Character and line based layer over a BufferedIOBase object, buffer.

    encoding gives the name of the encoding that the stream will be

    decoded or encoded with. It defaults to locale.getpreferredencoding(False).

    errors determines the strictness of encoding and decoding (see

    help(codecs.Codec) or the documentation for codecs.register) and

    defaults to "strict".

    newline controls how line endings are handled. It can be None, '',

    '\n', '\r', and '\r\n'.  It works as follows:

    * On input, if newline is None, universal newlines mode is

      enabled. Lines in the input can end in '\n', '\r', or '\r\n', and

      these are translated into '\n' before being returned to the

      caller. If it is '', universal newline mode is enabled, but line

      endings are returned to the caller untranslated. If it has any of

      the other legal values, input lines are only terminated by the given

      string, and the line ending is returned to the caller untranslated.

    * On output, if newline is None, any '\n' characters written are

      translated to the system default line separator, os.linesep. If

      newline is '' or '\n', no translation takes place. If newline is any

      of the other legal values, any '\n' characters written are translated

      to the given string.

    If line_buffering is True, a call to flush is implied when a call to

    write contains a newline character.

    """

    def close(self, *args, **kwargs): # real signature unknown

        关闭文件

        pass

    def fileno(self, *args, **kwargs): # real signature unknown

        文件描述符

        pass

    def flush(self, *args, **kwargs): # real signature unknown

        刷新文件内部缓冲区

        pass

    def isatty(self, *args, **kwargs): # real signature unknown

        判断文件是否是同意tty设备

        pass

    def read(self, *args, **kwargs): # real signature unknown

        读取指定字节数据

        pass

    def readable(self, *args, **kwargs): # real signature unknown

        是否可读

        pass

    def readline(self, *args, **kwargs): # real signature unknown

        仅读取一行数据

        pass

    def seek(self, *args, **kwargs): # real signature unknown

        指定文件中指针位置

        pass

    def seekable(self, *args, **kwargs): # real signature unknown

        指针是否可操作

        pass

    def tell(self, *args, **kwargs): # real signature unknown

        获取指针位置

        pass

    def truncate(self, *args, **kwargs): # real signature unknown

        截断数据，仅保留指定之前数据

        pass

    def writable(self, *args, **kwargs): # real signature unknown

        是否可写

        pass

    def write(self, *args, **kwargs): # real signature unknown

        写内容

        pass

    def __getstate__(self, *args, **kwargs): # real signature unknown

        pass

    def __init__(self, *args, **kwargs): # real signature unknown

        pass

    @staticmethod # known case of __new__

    def __new__(*args, **kwargs): # real signature unknown

        """ Create and return a new object.  See help(type) for accurate signature. """

        pass

    def __next__(self, *args, **kwargs): # real signature unknown

        """ Implement next(self). """

        pass

    def __repr__(self, *args, **kwargs): # real signature unknown

        """ Return repr(self). """

        pass

    buffer = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default

    closed = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default

    encoding = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default

    errors = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default

    line_buffering = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default

    name = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default

    newlines = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default

    _CHUNK_SIZE = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default

    _finalizing = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default

3.x

with open('log','r') as f:

    ...

with open('log1') as obj1, open('log2') as obj2:

    pass

open(filename, mode)

>>> f = open('/Users/michael/test.txt', 'r')

>>> f=open('/Users/michael/notfound.txt', 'r')

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

FileNotFoundError: [Errno 2] No such file or directory: '/Users/michael/notfound.txt'

#!/usr/bin/python3

# 打开一个文件

f = open("/tmp/foo.txt", "w")

f.write( "Python 是一个非常好的语言。\n是的，的确非常好!!\n" )

# 关闭打开的文件

f.close()

$ cat /tmp/foo.txt

Python 是一个非常好的语言。

是的，的确非常好!!

>>> f = open('/Users/michael/test.jpg', 'rb')

>>> f.read()

b'\xff\xd8\xff\xe1\x00\x18Exif\x00\x00...' # 十六进制表示的字节

>>> f = open('/Users/michael/gbk.txt', 'r', encoding='gbk')

>>> f.read()

'测试'

>>> f = open('/Users/michael/gbk.txt', 'r', encoding='gbk', errors='ignore')

#!/usr/bin/python3

# 打开一个文件

f = open("/tmp/foo.txt", "r")

str = f.read()

print(str)

# 关闭打开的文件

f.close()

Python 是一个非常好的语言。

是的，的确非常好!!

#!/usr/bin/python3

# 打开一个文件

f = open("/tmp/foo.txt", "r")

str = f.readline()

print(str)

# 关闭打开的文件

f.close()

Python 是一个非常好的语言。

#!/usr/bin/python3

# 打开一个文件

f = open("/tmp/foo.txt", "r")

str = f.readlines()

print(str)

# 关闭打开的文件

f.close()

['Python 是一个非常好的语言。\n', '是的，的确非常好!!\n']

#!/usr/bin/python3

# 打开一个文件

f = open("/tmp/foo.txt", "r")

for line in f:

    print(line, end='')

# 关闭打开的文件

f.close()

python是一个非常好的语言

是的，的确非常好！！

#!/usr/bin/python3

# 打开一个文件

f = open("/tmp/foo.txt", "w")

num = f.write( "Python 是一个非常好的语言。\n是的，的确非常好!!\n" )

print(num)

# 关闭打开的文件

f.close()

#!/usr/bin/python3

# 打开一个文件

f = open("/tmp/foo1.txt", "w")

value = ('www.baidu.com', 14)

s = str(value)

f.write(s)

# 关闭打开的文件

f.close()

$ cat /tmp/foo1.txt

('www.baidu.com', 14)

with open('log','r') as f:

    ...

with open('log1') as obj1, open('log2') as obj2:

    pass

>>> f = open('/tmp/foo.txt', 'rb+')

>>> f.write(b'0123456789abcdef')

16

>>> f.seek(5)     # 移动到文件的第六个字节

5

>>> f.read(1)

b'5'

>>> f.seek(-3, 2) # 移动到文件的倒数第三字节

13

>>> f.read(1)

b'd'

import sys,time

for i in  range(10):

    sys.stdout.write('#')

    sys.stdout.flush()

    time.sleep(0.2)

>>> f.close()

>>> f.read()

Traceback (most recent call last):

  File "<stdin>", line 1, in ?

ValueError: I/O operation on closed file

<pre>

<p>

当处理一个文件对象时, 使用 with 关键字是非常好的方式。在结束后, 它会帮你正确的关闭文件。 而且写起来也比 try - finally 语句块要简短:</p>

<pre>

>>> with open('/tmp/foo.txt', 'r') as f:

...     read_data = f.read()

>>> f.closed

True

pickle是Python库中常用的序列化工具，可以将内存对象以文本或二进制格式导出为字符串，或者写入文档。后续可以从字符或文档中还原为内存对象。新版本的Python中用c重新实现了一遍，叫cPickle，性能更高。 下面的代码演示了pickle库的常用接口用法，非常简单：

import cPickle as pickle

# dumps and loads

# 将内存对象dump为字符串，或者将字符串load为内存对象

def test_dumps_and_loads():

    t = {'name': ['v1', 'v2']}

    print t

    o = pickle.dumps(t)

    print o

    print 'len o: ', len(o)

    p = pickle.loads(o)

    print p

# 关于HIGHEST_PROTOCOL参数，pickle 支持3种protocol，0、1、2：

# http://*.com/questions/23582489/python-pickle-protocol-choice

# 0：ASCII protocol，兼容旧版本的Python

# 1：binary format，兼容旧版本的Python

# 2：binary format，Python2.3 之后才有，更好的支持new-sytle class

def test_dumps_and_loads_HIGHEST_PROTOCOL():

    print 'HIGHEST_PROTOCOL: ', pickle.HIGHEST_PROTOCOL

    t = {'name': ['v1', 'v2']}

    print t

    o = pickle.dumps(t, pickle.HIGHEST_PROTOCOL)

    print 'len o: ', len(o)

    p = pickle.loads(o)

    print p

# new-style class

def test_new_sytle_class():

    class TT(object):

        def __init__(self, arg, **kwargs):

            super(TT, self).__init__()

            self.arg = arg

            self.kwargs = kwargs

        def test(self):

            print self.arg

            print self.kwargs

    # ASCII protocol

    t = TT('test', a=1, b=2)

    o1 = pickle.dumps(t)

    print o1

    print 'o1 len: ', len(o1)

    p = pickle.loads(o1)

    p.test()

    # HIGHEST_PROTOCOL对new-style class支持更好，性能更高

    o2 = pickle.dumps(t, pickle.HIGHEST_PROTOCOL)

    print 'o2 len: ', len(o2)

    p = pickle.loads(o2)

    p.test()

# dump and load

# 将内存对象序列化后直接dump到文件或支持文件接口的对象中

# 对于dump，需要支持write接口，接受一个字符串作为输入参数，比如：StringIO

# 对于load，需要支持read接口，接受int输入参数，同时支持readline接口，无输入参数，比如StringIO

# 使用文件，ASCII编码

def test_dump_and_load_with_file():

    t = {'name': ['v1', 'v2']}

    # ASCII format

    with open('test.txt', 'w') as fp:

        pickle.dump(t, fp)

    with open('test.txt', 'r') as fp:

        p = pickle.load(fp)

        print p

# 使用文件，二进制编码

def test_dump_and_load_with_file_HIGHEST_PROTOCOL():

    t = {'name': ['v1', 'v2']}

    with open('test.bin', 'wb') as fp:

        pickle.dump(t, fp, pickle.HIGHEST_PROTOCOL)

    with open('test.bin', 'rb') as fp:

        p = pickle.load(fp)

        print p

# 使用StringIO，二进制编码

def test_dump_and_load_with_StringIO():

    import StringIO

    t = {'name': ['v1', 'v2']}

    fp = StringIO.StringIO()

    pickle.dump(t, fp, pickle.HIGHEST_PROTOCOL)

    fp.seek(0)

    p = pickle.load(fp)

    print p

    fp.close()

# 使用自定义类

# 这里演示用户自定义类，只要实现了write、read、readline接口，

# 就可以用作dump、load的file参数

def test_dump_and_load_with_user_def_class():

    import StringIO

    class FF(object):

        def __init__(self):

            self.buf = StringIO.StringIO()

        def write(self, s):

            self.buf.write(s)

            print 'len: ', len(s)

        def read(self, n):

            return self.buf.read(n)

        def readline(self):

            return self.buf.readline()

        def seek(self, pos, mod=0):

            return self.buf.seek(pos, mod)

        def close(self):

            self.buf.close()

    fp = FF()

    t = {'name': ['v1', 'v2']}

    pickle.dump(t, fp, pickle.HIGHEST_PROTOCOL)

    fp.seek(0)

    p = pickle.load(fp)

    print p

    fp.close()

# Pickler/Unpickler

# Pickler(file, protocol).dump(obj) 等价于 pickle.dump(obj, file[, protocol])

# Unpickler(file).load() 等价于 pickle.load(file)

# Pickler/Unpickler 封装性更好，可以很方便的替换file

def test_pickler_unpickler():

    t = {'name': ['v1', 'v2']}

    f = file('test.bin', 'wb')

    pick = pickle.Pickler(f, pickle.HIGHEST_PROTOCOL)

    pick.dump(t)

    f.close()

    f = file('test.bin', 'rb')

    unpick = pickle.Unpickler(f)

    p = unpick.load()

    print p

    f.close()

pickle.dump(obj, file, [,protocol])

x = pickle.load(file)

#!/usr/bin/python3

import pickle

# 使用pickle模块将数据对象保存到文件

data1 = {'a': [1, 2.0, 3, 4+6j],

         'b': ('string', u'Unicode string'),

         'c': None}

selfref_list = [1, 2, 3]

selfref_list.append(selfref_list)

output = open('data.pkl', 'wb')

# Pickle dictionary using protocol 0.

pickle.dump(data1, output)

# Pickle the list using the highest protocol available.

pickle.dump(selfref_list, output, -1)

output.close()

#!/usr/bin/python3

import pprint, pickle

#使用pickle模块从文件中重构python对象

pkl_file = open('data.pkl', 'rb')

data1 = pickle.load(pkl_file)

pprint.pprint(data1)

data2 = pickle.load(pkl_file)

pprint.pprint(data2)

pkl_file.close()

>>> import os

>>> os.name # 操作系统类型

'posix'

>>> os.uname()

posix.uname_result(sysname='Darwin', nodename='MichaelMacPro.local', release='14.3.0', version='Darwin Kernel Version 14.3.0: Mon Mar 23 11:59:05 PDT 2015; root:xnu-2782.20.48~5/RELEASE_X86_64', machine='x86_64')

>>> os.environ

environ({'VERSIONER_PYTHON_PREFER_32_BIT': 'no', 'TERM_PROGRAM_VERSION': '326', 'LOGNAME': 'michael', 'USER': 'michael', 'PATH': '/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/opt/X11/bin:/usr/local/mysql/bin', ...})

>>> os.environ.get('PATH')

'/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/opt/X11/bin:/usr/local/mysql/bin'

>>> os.environ.get('x', 'default')

'default'

# 查看当前目录的绝对路径:

>>> os.path.abspath('.')

'/Users/michael'

# 在某个目录下创建一个新目录，首先把新目录的完整路径表示出来:

>>> os.path.join('/Users/michael', 'testdir')

'/Users/michael/testdir'

# 然后创建一个目录:

>>> os.mkdir('/Users/michael/testdir')

# 删掉一个目录:

>>> os.rmdir('/Users/michael/testdir')

part-1/part-2

part-1\part-2