python-day05

这周作业所遇到的麻烦，从在主程序中使用return,报return not functions error,明白return 一般只能在函数中使用，表示返回出去

再者就是模块的导入，在模块的导入的时候我们需要注意首先因为这个pycharm解释器的存在所以我们可以看到在sys.path里面自动帮我们添加当前目录进入环境变量，实际上再cmd下是看不到这个存在的，所以要想真正意义上的存在，我们需要使用sys.path.append(path)

并且在导入模块后，如果我们不在各个模块的末尾加上这么一句if __name__ == ‘__main__‘:,，我们会看到有些我们还没有使用这个模块，它就自动调用其中某个函数了，这又是为什么呢接下来我们来揭开它的面纱

模块是对象，并且所有的模块都有一个内置属性 __name__。一个模块的 __name__ 的值取决于您如何应用模块。如果 import 一个模块，那么模块__name__ 的值通常为模块文件名，不带路径或者文件扩展名。但是您也可以像一个标准的程序样直接运行模块，在这 种情况下, __name__ 的值将是一个特别缺省"__main__"，示例来源于网络，简单的说就是我们为了避免导入到其他模块中的时候出现非自动调用，我们就需要用上这么一句加以让解释器区分主次

在cmd 中直接运行.py文件,则__name__的值是‘__main__‘;

而在import 一个.py文件后,__name__的值就不是‘__main__‘了;

从而用if __name__ == ‘__main__‘来判断是否是在直接运行该.py文件

如:

#Test.py

class Test:

def __init(self):pass

def f(self):print ‘Hello, World!‘

if __name__ == ‘__main__‘:

Test().f()

#End

你在cmd中输入:

C:>python Test.py

Hello, World!

说明:"__name__ == ‘__main__‘"是成立的

你再在cmd中输入:

C:>python

>>>import Test

>>>Test.__name__                #Test模块的__name__

‘Test‘

>>>__name__                       #当前程序的__name__

‘__main__‘

无论怎样,Test.py中的"__name__ == ‘__main__‘"都不会成立的!

所以,下一行代码永远不会运行到!

//////////////////////////////////////////////////////////////////////////////////

time模块或者date模块,

 1 #_*_coding:utf-8_*_
 2 import time
 3 import datetime
 4
 5 print(time.clock()) #返回处理器时间,3.3开始已废弃
 6 print(time.process_time()) #返回处理器时间,3.3开始已废弃
 7 print(time.time()) #返回当前系统时间戳
 8 print(time.ctime()) #输出Tue Jan 26 18:23:48 2016 ,当前系统时间
 9 print(time.ctime(time.time()-86640)) #将时间戳转为字符串格式
10 print(time.gmtime(time.time()-86640)) #将时间戳转换成struct_time格式
11 print(time.localtime(time.time()-86640)) #将时间戳转换成struct_time格式,但返回 的本地时间
12 print(time.mktime(time.localtime())) #与time.localtime()功能相反,将struct_time格式转回成时间戳格式
13 #time.sleep(4) #sleep
14 print(time.strftime("%Y-%m-%d %H:%M:%S",time.gmtime()) ) #将struct_time格式转成指定的字符串格式
15 print(time.strptime("2016-01-28","%Y-%m-%d") ) #将字符串格式转换成struct_time格式
16
17 #datetime module
18
19 print(datetime.date.today()) #输出格式 2016-01-26
20 print(datetime.date.fromtimestamp(time.time()-864400) ) #2016-01-16 将时间戳转成日期格式
21 current_time = datetime.datetime.now() #
22 print(current_time) #输出2016-01-26 19:04:30.335935
23 print(current_time.timetuple()) #返回struct_time格式
24
25 #datetime.replace([year[, month[, day[, hour[, minute[, second[, microsecond[, tzinfo]]]]]]]])
26 print(current_time.replace(2014,9,12)) #输出2014-09-12 19:06:24.074900,返回当前时间,但指定的值将被替换
27
28 str_to_date = datetime.datetime.strptime("21/11/06 16:30", "%d/%m/%y %H:%M") #将字符串转换成日期格式
29 new_date = datetime.datetime.now() + datetime.timedelta(days=10) #比现在加10天
30 new_date = datetime.datetime.now() + datetime.timedelta(days=-10) #比现在减10天
31 new_date = datetime.datetime.now() + datetime.timedelta(hours=-10) #比现在减10小时
32 new_date = datetime.datetime.now() + datetime.timedelta(seconds=120) #比现在+120s
33 print(new_date)

OS模块　　

提供对操作系统进行调用的接口

 1 os.getcwd() 获取当前工作目录，即当前python脚本工作的目录路径
 2 os.chdir("dirname")  改变当前脚本工作目录；相当于shell下cd
 3 os.curdir  返回当前目录: (‘.‘)
 4 os.pardir  获取当前目录的父目录字符串名：(‘..‘)
 5 os.makedirs(‘dirname1/dirname2‘)    可生成多层递归目录
 6 os.removedirs(‘dirname1‘)    若目录为空，则删除，并递归到上一级目录，如若也为空，则删除，依此类推
 7 os.mkdir(‘dirname‘)    生成单级目录；相当于shell中mkdir dirname
 8 os.rmdir(‘dirname‘)    删除单级空目录，若目录不为空则无法删除，报错；相当于shell中rmdir dirname
 9 os.listdir(‘dirname‘)    列出指定目录下的所有文件和子目录，包括隐藏文件，并以列表方式打印
10 os.remove()  删除一个文件
11 os.rename("oldname","newname")  重命名文件/目录
12 os.stat(‘path/filename‘)  获取文件/目录信息
13 os.sep    输出操作系统特定的路径分隔符，win下为"\\",Linux下为"/"
14 os.linesep    输出当前平台使用的行终止符，win下为"\t\n",Linux下为"\n"
15 os.pathsep    输出用于分割文件路径的字符串
16 os.name    输出字符串指示当前使用平台。win->‘nt‘; Linux->‘posix‘
17 os.system("bash command")  运行shell命令，直接显示
18 os.environ  获取系统环境变量
19 os.path.abspath(path)  返回path规范化的绝对路径
20 os.path.split(path)  将path分割成目录和文件名二元组返回
21 os.path.dirname(path)  返回path的目录。其实就是os.path.split(path)的第一个元素
22 os.path.basename(path)  返回path最后的文件名。如何path以／或\结尾，那么就会返回空值。即os.path.split(path)的第二个元素
23 os.path.exists(path)  如果path存在，返回True；如果path不存在，返回False
24 os.path.isabs(path)  如果path是绝对路径，返回True
25 os.path.isfile(path)  如果path是一个存在的文件，返回True。否则返回False
26 os.path.isdir(path)  如果path是一个存在的目录，则返回True。否则返回False
27 os.path.join(path1[, path2[, ...]])  将多个路径组合后返回，第一个绝对路径之前的参数将被忽略
28 os.path.getatime(path)  返回path所指向的文件或者目录的最后存取时间
29 os.path.getmtime(path)  返回path所指向的文件或者目录的最后修改时间

random模块

随机数

1 import random
2 print random.random()
3 print random.randint(1,2)
4 print random.randrange(1,10)

生成随机验证码

 1 import random
 2 checkcode = ‘‘
 3 for i in range(4):
 4     current = random.randrange(0,4)
 5     if current != i:
 6         temp = chr(random.randint(65,90))
 7     else:
 8         temp = random.randint(0,9)
 9     checkcode += str(temp)
10 print checkcode

sys模块

用于提供对Python解释器相关的操作：

1 sys.argv           命令行参数List，第一个元素是程序本身路径
2 sys.exit(n)        退出程序，正常退出时exit(0)
3 sys.version        获取Python解释程序的版本信息
4 sys.maxint         最大的Int值
5 sys.path           返回模块的搜索路径，初始化时使用PYTHONPATH环境变量的值
6 sys.platform       返回操作系统平台名称
7 sys.stdin          输入相关
8 sys.stdout         输出相关
9 sys.stderror       错误相关

进度百分比

 1 import sys
 2 import time
 3
 4
 5 def view_bar(num, total):
 6     rate = float(num) / float(total)
 7     rate_num = int(rate * 100)
 8     r = ‘\r%d%%‘ % (rate_num, )
 9     sys.stdout.write(r)
10     sys.stdout.flush()
11
12
13 if __name__ == ‘__main__‘:
14     for i in range(0, 100):
15         time.sleep(0.1)
16         view_bar(i, 100)

hashlib

用于加密相关的操作，代替了md5模块和sha模块，主要提供 SHA1, SHA224, SHA256, SHA384, SHA512 ，MD5 算法

 1 import hashlib
 2
 3 # ######## md5 ########
 4 hash = hashlib.md5()
 5 # help(hash.update)
 6 hash.update(bytes(‘admin‘, encoding=‘utf-8‘))
 7 print(hash.hexdigest())
 8 print(hash.digest())
 9
10
11 ######## sha1 ########
12
13 hash = hashlib.sha1()
14 hash.update(bytes(‘admin‘, encoding=‘utf-8‘))
15 print(hash.hexdigest())
16
17 # ######## sha256 ########
18
19 hash = hashlib.sha256()
20 hash.update(bytes(‘admin‘, encoding=‘utf-8‘))
21 print(hash.hexdigest())
22
23
24 # ######## sha384 ########
25
26 hash = hashlib.sha384()
27 hash.update(bytes(‘admin‘, encoding=‘utf-8‘))
28 print(hash.hexdigest())
29
30 # ######## sha512 ########
31
32 hash = hashlib.sha512()
33 hash.update(bytes(‘admin‘, encoding=‘utf-8‘))
34 print(hash.hexdigest())

以上加密算法虽然依然非常厉害，但时候存在缺陷，即：通过撞库可以反解。所以，有必要对加密算法中添加自定义key再来做加密。

1 import hashlib
2
3 # ######## md5 ########
4
5 hash = hashlib.md5(bytes(‘898oaFs09f‘,encoding="utf-8"))
6 hash.update(bytes(‘admin‘,encoding="utf-8"))
7 print(hash.hexdigest())

python内置还有一个 hmac 模块，它内部对我们创建 key 和 内容 进行进一步的处理然后再加密

1 import hmac
2
3 h = hmac.new(bytes(‘898oaFs09f‘,encoding="utf-8"))
4 h.update(bytes(‘admin‘,encoding="utf-8"))
5 print(h.hexdigest())

序列化

Python中用于序列化的两个模块

• json     用于【字符串】和 【python基本数据类型】 间进行转换
• pickle   用于【python特有的类型】 和 【python基本数据类型】间进行转换

Json模块提供了四个功能：dumps、dump、loads、load

pickle模块提供了四个功能：dumps、dump、loads、load

shutil

高级的 文件、文件夹、压缩包 处理模块

shutil.copyfileobj(fsrc, fdst[, length])
将文件内容拷贝到另一个文件中，可以部分内容

1 def copyfileobj(fsrc, fdst, length=16*1024):
2     """copy data from file-like object fsrc to file-like object fdst"""
3     while 1:
4         buf = fsrc.read(length)
5         if not buf:
6             break
7         fdst.write(buf)

shutil.copyfile(src, dst)
拷贝文件

 1 def copyfile(src, dst):
 2     """Copy data from src to dst"""
 3     if _samefile(src, dst):
 4         raise Error("`%s` and `%s` are the same file" % (src, dst))
 5
 6     for fn in [src, dst]:
 7         try:
 8             st = os.stat(fn)
 9         except OSError:
10             # File most likely does not exist
11             pass
12         else:
13             # XXX What about other special files? (sockets, devices...)
14             if stat.S_ISFIFO(st.st_mode):
15                 raise SpecialFileError("`%s` is a named pipe" % fn)
16
17     with open(src, ‘rb‘) as fsrc:
18         with open(dst, ‘wb‘) as fdst:
19             copyfileobj(fsrc, fdst)

shutil.copymode(src, dst)
仅拷贝权限。内容、组、用户均不变

1 def copymode(src, dst):
2     """Copy mode bits from src to dst"""
3     if hasattr(os, ‘chmod‘):
4         st = os.stat(src)
5         mode = stat.S_IMODE(st.st_mode)
6         os.chmod(dst, mode)

shutil.copystat(src, dst)
拷贝状态的信息，包括：mode bits, atime, mtime, flags

 1 def copystat(src, dst):
 2     """Copy all stat info (mode bits, atime, mtime, flags) from src to dst"""
 3     st = os.stat(src)
 4     mode = stat.S_IMODE(st.st_mode)
 5     if hasattr(os, ‘utime‘):
 6         os.utime(dst, (st.st_atime, st.st_mtime))
 7     if hasattr(os, ‘chmod‘):
 8         os.chmod(dst, mode)
 9     if hasattr(os, ‘chflags‘) and hasattr(st, ‘st_flags‘):
10         try:
11             os.chflags(dst, st.st_flags)
12         except OSError, why:
13             for err in ‘EOPNOTSUPP‘, ‘ENOTSUP‘:
14                 if hasattr(errno, err) and why.errno == getattr(errno, err):
15                     break
16             else:
17                 raise

shutil.copy(src, dst)
拷贝文件和权限

 1 def copy(src, dst):
 2     """Copy data and mode bits ("cp src dst").
 3
 4     The destination may be a directory.
 5
 6     """
 7     if os.path.isdir(dst):
 8         dst = os.path.join(dst, os.path.basename(src))
 9     copyfile(src, dst)
10     copymode(src, dst)

shutil.copy2(src, dst)
拷贝文件和状态信息

 1 def copy2(src, dst):
 2     """Copy data and all stat info ("cp -p src dst").
 3
 4     The destination may be a directory.
 5
 6     """
 7     if os.path.isdir(dst):
 8         dst = os.path.join(dst, os.path.basename(src))
 9     copyfile(src, dst)
10     copystat(src, dst)

shutil.ignore_patterns(*patterns)
shutil.copytree(src, dst, symlinks=False, ignore=None)
递归的去拷贝文件

例如：copytree(source, destination, ignore=ignore_patterns(‘*.pyc‘, ‘tmp*‘))

 1 def ignore_patterns(*patterns):
 2     """Function that can be used as copytree() ignore parameter.
 3
 4     Patterns is a sequence of glob-style patterns
 5     that are used to exclude files"""
 6     def _ignore_patterns(path, names):
 7         ignored_names = []
 8         for pattern in patterns:
 9             ignored_names.extend(fnmatch.filter(names, pattern))
10         return set(ignored_names)
11     return _ignore_patterns
12
13 def copytree(src, dst, symlinks=False, ignore=None):
14     """Recursively copy a directory tree using copy2().
15
16     The destination directory must not already exist.
17     If exception(s) occur, an Error is raised with a list of reasons.
18
19     If the optional symlinks flag is true, symbolic links in the
20     source tree result in symbolic links in the destination tree; if
21     it is false, the contents of the files pointed to by symbolic
22     links are copied.
23
24     The optional ignore argument is a callable. If given, it
25     is called with the `src` parameter, which is the directory
26     being visited by copytree(), and `names` which is the list of
27     `src` contents, as returned by os.listdir():
28
29         callable(src, names) -> ignored_names
30
31     Since copytree() is called recursively, the callable will be
32     called once for each directory that is copied. It returns a
33     list of names relative to the `src` directory that should
34     not be copied.
35
36     XXX Consider this example code rather than the ultimate tool.
37
38     """
39     names = os.listdir(src)
40     if ignore is not None:
41         ignored_names = ignore(src, names)
42     else:
43         ignored_names = set()
44
45     os.makedirs(dst)
46     errors = []
47     for name in names:
48         if name in ignored_names:
49             continue
50         srcname = os.path.join(src, name)
51         dstname = os.path.join(dst, name)
52         try:
53             if symlinks and os.path.islink(srcname):
54                 linkto = os.readlink(srcname)
55                 os.symlink(linkto, dstname)
56             elif os.path.isdir(srcname):
57                 copytree(srcname, dstname, symlinks, ignore)
58             else:
59                 # Will raise a SpecialFileError for unsupported file types
60                 copy2(srcname, dstname)
61         # catch the Error from the recursive copytree so that we can
62         # continue with other files
63         except Error, err:
64             errors.extend(err.args[0])
65         except EnvironmentError, why:
66             errors.append((srcname, dstname, str(why)))
67     try:
68         copystat(src, dst)
69     except OSError, why:
70         if WindowsError is not None and isinstance(why, WindowsError):
71             # Copying file access times may fail on Windows
72             pass
73         else:
74             errors.append((src, dst, str(why)))
75     if errors:
76         raise Error, errors

shutil.rmtree(path[, ignore_errors[, onerror]])
递归的去删除文件

 1 def rmtree(path, ignore_errors=False, onerror=None):
 2     """Recursively delete a directory tree.
 3
 4     If ignore_errors is set, errors are ignored; otherwise, if onerror
 5     is set, it is called to handle the error with arguments (func,
 6     path, exc_info) where func is os.listdir, os.remove, or os.rmdir;
 7     path is the argument to that function that caused it to fail; and
 8     exc_info is a tuple returned by sys.exc_info().  If ignore_errors
 9     is false and onerror is None, an exception is raised.
10
11     """
12     if ignore_errors:
13         def onerror(*args):
14             pass
15     elif onerror is None:
16         def onerror(*args):
17             raise
18     try:
19         if os.path.islink(path):
20             # symlinks to directories are forbidden, see bug #1669
21             raise OSError("Cannot call rmtree on a symbolic link")
22     except OSError:
23         onerror(os.path.islink, path, sys.exc_info())
24         # can‘t continue even if onerror hook returns
25         return
26     names = []
27     try:
28         names = os.listdir(path)
29     except os.error, err:
30         onerror(os.listdir, path, sys.exc_info())
31     for name in names:
32         fullname = os.path.join(path, name)
33         try:
34             mode = os.lstat(fullname).st_mode
35         except os.error:
36             mode = 0
37         if stat.S_ISDIR(mode):
38             rmtree(fullname, ignore_errors, onerror)
39         else:
40             try:
41                 os.remove(fullname)
42             except os.error, err:
43                 onerror(os.remove, fullname, sys.exc_info())
44     try:
45         os.rmdir(path)
46     except os.error:
47         onerror(os.rmdir, path, sys.exc_info())

shutil.move(src, dst)
递归的去移动文件

 1 def move(src, dst):
 2     """Recursively move a file or directory to another location. This is
 3     similar to the Unix "mv" command.
 4
 5     If the destination is a directory or a symlink to a directory, the source
 6     is moved inside the directory. The destination path must not already
 7     exist.
 8
 9     If the destination already exists but is not a directory, it may be
10     overwritten depending on os.rename() semantics.
11
12     If the destination is on our current filesystem, then rename() is used.
13     Otherwise, src is copied to the destination and then removed.
14     A lot more could be done here...  A look at a mv.c shows a lot of
15     the issues this implementation glosses over.
16
17     """
18     real_dst = dst
19     if os.path.isdir(dst):
20         if _samefile(src, dst):
21             # We might be on a case insensitive filesystem,
22             # perform the rename anyway.
23             os.rename(src, dst)
24             return
25
26         real_dst = os.path.join(dst, _basename(src))
27         if os.path.exists(real_dst):
28             raise Error, "Destination path ‘%s‘ already exists" % real_dst
29     try:
30         os.rename(src, real_dst)
31     except OSError:
32         if os.path.isdir(src):
33             if _destinsrc(src, dst):
34                 raise Error, "Cannot move a directory ‘%s‘ into itself ‘%s‘." % (src, dst)
35             copytree(src, real_dst, symlinks=True)
36             rmtree(src)
37         else:
38             copy2(src, real_dst)
39             os.unlink(src)

shutil.make_archive(base_name, format,...)

创建压缩包并返回文件路径，例如：zip、tar

• base_name： 压缩包的文件名，也可以是压缩包的路径。只是文件名时，则保存至当前目录，否则保存至指定路径，
  如：www                        =>保存至当前路径
  如：/Users/wupeiqi/www =>保存至/Users/wupeiqi/
• format： 压缩包种类，“zip”, “tar”, “bztar”，“gztar”
• root_dir： 要压缩的文件夹路径（默认当前目录）
• owner： 用户，默认当前用户
• group： 组，默认当前组
• logger： 用于记录日志，通常是logging.Logger对象
• 

  1 #将 /Users/wupeiqi/Downloads/test 下的文件打包放置当前程序目录
  2
  3 import shutil
  4 ret = shutil.make_archive("wwwwwwwwww", ‘gztar‘, root_dir=‘/Users/wupeiqi/Downloads/test‘)
  5
  6
  7 #将 /Users/wupeiqi/Downloads/test 下的文件打包放置 /Users/wupeiqi/目录
  8 import shutil
  9 ret = shutil.make_archive("/Users/wupeiqi/wwwwwwwwww", ‘gztar‘, root_dir=‘/Users/wupeiqi/Downloads/test‘)

• 

   1 def make_archive(base_name, format, root_dir=None, base_dir=None, verbose=0,
   2                  dry_run=0, owner=None, group=None, logger=None):
   3     """Create an archive file (eg. zip or tar).
   4
   5     ‘base_name‘ is the name of the file to create, minus any format-specific
   6     extension; ‘format‘ is the archive format: one of "zip", "tar", "bztar"
   7     or "gztar".
   8
   9     ‘root_dir‘ is a directory that will be the root directory of the
  10     archive; ie. we typically chdir into ‘root_dir‘ before creating the
  11     archive.  ‘base_dir‘ is the directory where we start archiving from;
  12     ie. ‘base_dir‘ will be the common prefix of all files and
  13     directories in the archive.  ‘root_dir‘ and ‘base_dir‘ both default
  14     to the current directory.  Returns the name of the archive file.
  15
  16     ‘owner‘ and ‘group‘ are used when creating a tar archive. By default,
  17     uses the current owner and group.
  18     """
  19     save_cwd = os.getcwd()
  20     if root_dir is not None:
  21         if logger is not None:
  22             logger.debug("changing into ‘%s‘", root_dir)
  23         base_name = os.path.abspath(base_name)
  24         if not dry_run:
  25             os.chdir(root_dir)
  26
  27     if base_dir is None:
  28         base_dir = os.curdir
  29
  30     kwargs = {‘dry_run‘: dry_run, ‘logger‘: logger}
  31
  32     try:
  33         format_info = _ARCHIVE_FORMATS[format]
  34     except KeyError:
  35         raise ValueError, "unknown archive format ‘%s‘" % format
  36
  37     func = format_info[0]
  38     for arg, val in format_info[1]:
  39         kwargs[arg] = val
  40
  41     if format != ‘zip‘:
  42         kwargs[‘owner‘] = owner
  43         kwargs[‘group‘] = group
  44
  45     try:
  46         filename = func(base_name, base_dir, **kwargs)
  47     finally:
  48         if root_dir is not None:
  49             if logger is not None:
  50                 logger.debug("changing back to ‘%s‘", save_cwd)
  51             os.chdir(save_cwd)
  52
  53     return filename

shutil 对压缩包的处理是调用 ZipFile 和 TarFile 两个模块来进行的，详细：

 1 import zipfile
 2
 3 # 压缩
 4 z = zipfile.ZipFile(‘laxi.zip‘, ‘w‘)
 5 z.write(‘a.log‘)
 6 z.write(‘data.data‘)
 7 z.close()
 8
 9 # 解压
10 z = zipfile.ZipFile(‘laxi.zip‘, ‘r‘)
11 z.extractall()
12 z.close()

 1 import tarfile
 2
 3 # 压缩
 4 tar = tarfile.open(‘your.tar‘,‘w‘)
 5 tar.add(‘/Users/wupeiqi/PycharmProjects/bbs2.zip‘, arcname=‘bbs2.zip‘)
 6 tar.add(‘/Users/wupeiqi/PycharmProjects/cmdb.zip‘, arcname=‘cmdb.zip‘)
 7 tar.close()
 8
 9 # 解压
10 tar = tarfile.open(‘your.tar‘,‘r‘)
11 tar.extractall()  # 可设置解压地址
12 tar.close()

tarfile 压缩解压

zipfile tarfile见源码