day22-Python运维开发基础(正则函数 / 异常处理)

1. 正则函数

# ### 正则表达式 => 正则函数
import re
# search   通过正则匹配出第一个对象返回，通过group取出对象中的值
strvar = "5*7 9/8"
obj = re.search("(\d+)[*/]\d+",strvar)
print(obj)
# group 获取匹配的内容
res = obj.group()
print(res)
res = obj.groups()
print(res)

# match    验证用户输入内容
"""search在正则表达式的前面加上^ 就与math函数一模一样"""
strvar = ""
strvar = "y17166668888"
obj = re.search("^\d+",strvar)
# print(obj.group())
print(obj)

obj = re.match("\d+",strvar)
# print(obj.group())
print(obj)

# split    切割
strvar = "alex|wusir|xboyww-xgirlww"
lst = strvar.replace("-","|").split("|")
print(lst)

# - 具有特殊的含义,使用时需要转义
strvar = "alex|wusir-xboyww&xgirlww"
res = re.split(r"[|\-&]",strvar)
print(res)

strvar = "alex2342wusir23423423242xboyww2222222xgirlww"
res = re.split("\d+",strvar)
print(res)

# split(正则表达式,字符串,[选择分割的次数,可选]) 返回列表
res = re.split("\d+",strvar,1)
print(res)

# sub      替换  返回的结果是一个字符串
strvar = "alex|wusir-xboyww&xgirlww"
res = re.sub(r"[|&-]","%",strvar)
print(res)
# sub(正则表达式,要替换的字符串,原字符串,[选择替换的次数,可选]) 返回字符串
res = re.sub(r"[|&-]","%",strvar,1)
print(res)

# subn     替换 用法上与sub一样,但是返回的结果是元组,(替换后的结果,替换的次数)
strvar = "alex|wusir-xboyww&xgirlww"
res = re.subn(r"[|&-]","%",strvar,1)
print(res)

# finditer 匹配字符串中相应内容,返回迭代器
"""findall 与 finditer用法一样,区别在于 findall返回的是列表,finditer返回迭代器"""
from collections import Iterator,Iterable
strvar = "sdfsd&^*12招待费34sdf"
it = re.finditer("\d",strvar)
# 判断是否是迭代器
res = isinstance(it,Iterator)
print(res)

for i in it:
    # print(i)  #<_sre.SRE_Match object; span=(8, 9), match='1'>
    res = i.group()
    print(res)

# compile  指定一个统一的匹配规则
"""
正常情况下,需要先编译好正则表达式,再去执行匹配
如果频繁的反复使用,浪费时间和空间

所以使用compile 用来编译一次,终身受益,不用对同一个正则反复编译啦
"""
strvar = "sdfsd&^*12招待费34sdf"
pattern = re.compile("\d")
print(pattern)
res = pattern.findall(strvar)
print(res)

# 修饰符
# re.I 使匹配对大小写不敏感
strvar = "<h1>这是一个大标题</H1>"
pattern = re.compile("<h1>(.*?)</h1>",flags=re.I)
obj = pattern.search(strvar)
print(obj)
print(obj.group())
print(obj.groups())

# re.M 使每一行都能够单独匹配(多行匹配)，影响 ^ 和 $
strvar = """<a>sdfsdfsd</a>
<p>234234234</p>
<div>^&^&&%</div>
"""

pattern = re.compile("^<.*?>(.*?)<.*?>$",flags=re.M)
obj = pattern.search(strvar)
print(obj.group())
print(obj.groups())

lst = pattern.findall(strvar)
print(lst)

# re.S 使 . 匹配包括换行在内的所有字符
strvar = """
give
123mefive
"""
pattern = re.compile(".*?mefive",flags=re.S)
obj = pattern.search(strvar)
print(obj)
"""
# 不加修饰符,加上修饰,两个结果的差别;
123mefiiv
\ngive\n123mefive
"""

# 使用多个修饰符的写法 (拓展)
strvar = """<a>sdfsdfsd</a>
<p>234234234</p>
<div>^&^&&%</P>
"""
pattern = re.compile("^<.*?>(.*?)</p>$",flags=re.I|re.S)
obj = pattern.search(strvar)
print(obj.group())
print(obj.groups())

正则函数 示例代码

2. module(与类相关的魔术属性 / 反射 / sys.modules)

# ### (1)与类相关的魔术属性
class Man():
    pass

class Woman():
    pass

class Children(Man,Woman):
    """
    成员属性:eye skin
    成员方法:eat cry 私有sleep
    """

    eye = "天蓝色"
    skin = "天蓝色"

    def eat(self):
        print("小孩下来就会吃奶奶")

    def cry(self,func):
        print("小孩哭起来,地动山摇,天崩地裂,海枯石烂")
        print(func.__name__,type(func.__name__)) # 可以获取函数名或者类名

    def __sleep():
        print("小孩睡觉的时候,不喜欢别人干扰它")

obj = Children()
# __dict__ 获取对象或类的内部成员结构
# 对象
res = obj.__dict__
print(res)
# 类
res = Children.__dict__
print(res)

# __doc__  获取对象或类的内部文档
print(Children.__doc__)

# __name__ 获取类名函数名
def abc():
    print("abc")
obj.cry(abc)

# __class__ 获取当前对象所属的类
res = obj.__class__
print(res)

# __bases__ 获取一个类直接继承的所有父类,返回元组
print(Children.__bases__)

# ### (2) 反射
# 通过字符串去操对象 或者 模块中的属性方法

# (1)类中的反射
# 1.hasattr() 检测对象/类是否有指定的成员
# 对象
res = hasattr(obj,"eye")
print(res)
res = hasattr(obj,"eat")
print(res)

# 类
res = hasattr(Children,"skin")
print(res)

# 2.getattr() 获取对象/类成员的值
# 对象
res = getattr(obj,"eye")
print(res)
# 通过对象把方法反射出来,是绑定方法
func = getattr(obj,"eat")
print(func)
func()
# 通过类把方法反射出来,是普通方法
func = getattr(Children,"eat")
print(func)
func(1)
# 可以为getattr设置默认值,如果找不到该成员,在第三个参数上可以设置相应的返回值
res = getattr(Children,"abc","对不起,没有该成员")
print(res)

# 小应用
"""
strvar = input("请输入你要操作的成员:")
if hasattr(obj,strvar):
    func = getattr(obj,strvar)
    func()
else:
    print("对不起,没有该成员")
"""

# 3.setattr() 设置对象/类成员的值
# 对象
setattr(obj,"hair","天蓝色的")
print(obj.hair)
# 类
setattr(Children,"age",lambda : print("小孩下生后,是一个肉球"))
Children.age()

# 4.delattr() 删除对象/类成员的值
# 对象
delattr(obj,"hair")
# print(obj.hair)
# 类
delattr(Children,"age")
# Children.age()

# (2)模块的反射
import sys
# sys.modules 返回一个系统字典,字典的键是加载的所有模块
print(sys.modules)
"""
__main__
{'builtins': <module 'builtins' (built-in)>, 'sys': <module 'sys' (built-in)>, '_frozen_importlib': <module '_frozen_importlib' (frozen)>, '_imp': <module '_imp' (built-in)>, '_warnings': <module '_warnings' (built-in)>, '_thread': <module '_thread' (built-in)>, '_weakref': <module '_weakref' (built-in)>, '_frozen_importlib_external': <module '_frozen_importlib_external' (frozen)>, '_io': <module 'io' (built-in)>, 'marshal': <module 'marshal' (built-in)>, 'posix': <module 'posix' (built-in)>, 'zipimport': <module 'zipimport' (built-in)>, 'encodings': <module 'encodings' from '/usr/lib/python3.6/encodings/__init__.py'>, 'codecs': <module 'codecs' from '/usr/lib/python3.6/codecs.py'>, '_codecs': <module '_codecs' (built-in)>, 'encodings.aliases': <module 'encodings.aliases' from '/usr/lib/python3.6/encodings/aliases.py'>, 'encodings.utf_8': <module 'encodings.utf_8' from '/usr/lib/python3.6/encodings/utf_8.py'>, '_signal': <module '_signal' (built-in)>,
'__main__': <module '__main__' from '/mnt/hgfs/gongxiang8/day22/2.module.py'>, 'encodings.latin_1': <module 'encodings.latin_1' from '/usr/lib/python3.6/encodings/latin_1.py'>, 'io': <module 'io' from '/usr/lib/python3.6/io.py'>, 'abc': <module 'abc' from '/usr/lib/python3.6/abc.py'>, '_weakrefset': <module '_weakrefset' from '/usr/lib/python3.6/_weakrefset.py'>, 'site': <module 'site' from '/usr/lib/python3.6/site.py'>, 'os': <module 'os' from '/usr/lib/python3.6/os.py'>, 'errno': <module 'errno' (built-in)>, 'stat': <module 'stat' from '/usr/lib/python3.6/stat.py'>, '_stat': <module '_stat' (built-in)>, 'posixpath': <module 'posixpath' from '/usr/lib/python3.6/posixpath.py'>, 'genericpath': <module 'genericpath' from '/usr/lib/python3.6/genericpath.py'>, 'os.path': <module 'posixpath' from '/usr/lib/python3.6/posixpath.py'>, '_collections_abc': <module '_collections_abc' from '/usr/lib/python3.6/_collections_abc.py'>, '_sitebuiltins': <module '_sitebuiltins' from '/usr/lib/python3.6/_sitebuiltins.py'>, '_bootlocale': <module '_bootlocale' from '/usr/lib/python3.6/_bootlocale.py'>, '_locale': <module '_locale' (built-in)>, 'sysconfig': <module 'sysconfig' from '/usr/lib/python3.6/sysconfig.py'>, '_sysconfigdata_m_linux_x86_64-linux-gnu': <module '_sysconfigdata_m_linux_x86_64-linux-gnu' from '/usr/lib/python3.6/_sysconfigdata_m_linux_x86_64-linux-gnu.py'>, 'sitecustomize': <module 'sitecustomize' from '/usr/lib/python3.6/sitecustomize.py'>, 'encodings.cp437': <module 'encodings.cp437' from '/usr/lib/python3.6/encodings/cp437.py'>}

"""
mymodule = sys.modules["__main__"]
print(mymodule)

def func1():
    print(1)

def func2():
    print(2)

def func3():
    print(3)

def func4():
    print(4)

# 通过字符串操作模块中的成员
while True:
    func = input("请用户输入您要操作的函数")
    if hasattr(mymodule,func):
        # 反射真实的函数
        fuc = getattr(mymodule,func)
        fuc()
    else:
        print("这个函数不存在")

与类相关的魔术属性_反射_sys.modules 示例代码

3. 异常处理

# ### 了解异常处理

# IndexError                索引超出序列的范围
# lst = [1,2,3]
# print(lst[100])

# KeyError                  字典中查找一个不存在的关键字
# dic =  {"a":1}
# print(dic["b"])

# NameError                 尝试访问一个不存在的变量
# wangwen = 10
# print(wangwen)

# IndentationError          缩进错误
"""
if 5 == 5:
    print(1)
    print(2)
"""
# AttributeError            尝试访问未知的对象属性
class MyClass():
    a = 5

obj = MyClass()
# obj.b

# StopIteration             迭代器没有更多的值
"""
it = iter(range(3))
res = next(it)
res = next(it)
res = next(it)
res = next(it)
print(res)
"""

# AssertionError             断言语句（assert）失败
# assert 5>3
# assert 猜一猜 5<2是不是正确的,如果错误,直接抛出异常
assert 5<2

了解异常 示例代码

# ### 异常处理
"""
try:
    code1
except:
    code2

把可能存在问题的代码放到try这个代码块之后,
如果出现异常直接执行except这个代码块里面内容
如果没有异常,就不走except;
"""

# 1.基本语法
try:
    lst = [1,2,3]
    print(lst[100])
except:
    pass

# 2.带有分支的异常处理
try:
    # lst = [1,2,3]
    # print(lst[100])

    # dic = {"a":1}
    # print(dic["b"])

    print(wangwen)

except IndexError:
    print("我是IndexError错误类")
except KeyError:
    print("我是KeyError错误类")
except:
    print("有异常错误")

# 3.解决StopIteration错误异常,并且获取返回值
def gen():
    yield 1
    yield 2
    return 334343

# 初始化生成器 => 返回生成器对象 => 简称生成器

"""StopIteration as e 是给StopIteration这个类实例化出来的对象起别名叫e"""
try:
    mygen = gen()

    res = next(mygen)
    res = next(mygen)
    res = next(mygen)
except StopIteration as e:
    """
    对象可以直接打印,会自动触发__str__魔术方法,
    在系统内部自动接收return的返回值
    在打印对象时候,自动打印返回值
    """
    print(e)
    print("我是StopIteration错误")

# 4.关于异常处理的扩展写法
# try ... finally 如果再报错时,也必须要执行,就使用finally
"""
try:
    print(wangwen)
finally:
    print(1)
    print(2)
print(3)
"""
# try ... except ... else
# 如果不报错就走else分支,报错了就不执行else
"""
try:
    # print(lisi)
    print(1234)
except:
    pass
else:
    print(1)
    print(2)
"""

# finally 和 else 不能够同时存在
"""
try:
    print(wangwen)
except:
    pass
finally:
    print(5)
else:
    print(6)
"""

# for/while ... else ... (了解)
"""
如果循环异常终止(break,或者在函数中通过return终止的),不走else分支
"""
for i in range(10):
    # if i == 5:
        # break
    pass
else:
    print(111222)

异常处理 示例代码

# ### 主动抛出异常 raise
"""
所有异常类的父类(基类,超类)     BaseException
所有普通异常类的父类(基类,超类) Exception

raise + 异常类/异常类的对象

"""
# (1) 基本用法
try:
    raise BaseException
except BaseException:
    pass

# 简写
"""raise 后面如果什么也不写 , 默认抛出的是BaseException"""
try:
    raise
except :
    pass

# (2) 自定义异常类

# 只能在异常的情况下,才能获取到相应的数据
def return_errorinfo(n):
    import sys
    f = sys.exc_info()[2].tb_frame.f_back
    if n==1:
        return str(f.f_lineno)      #返回当前行数
    elif n == 2:
        return f.f_code.co_filename #返回文件名    

# 自定义异常类:(必须继承BaseException异常类父类)
class MyException(BaseException):
    def __init__(self,num,msg,file,fileline):
        # 错误号码
        self.num = num
        # 错误消息
        self.msg = msg
        # 错误文件
        self.file = file
        # 错误行号
        self.fileline = fileline

# get_info 通过抛出异常触发return_errorinfo函数,从而获取异常的行号和文件
def get_info(n):
    try:
        raise
    except:
        return return_errorinfo(n)

# 实际使用
sex = "中性"
try:
    if sex == "中性":
        # 主动抛出异常 (对象)
        raise MyException(200,"人类没有中性的",get_info(2),get_info(1))
except MyException as e:

    print("错误的号码是{}".format(e.num))
    print("错误的原因是{}".format(e.msg))
    print("错误的文件是{}".format(e.file))
    print("错误的行号是{}".format(e.fileline))

主动抛出异常raise 示例代码

day22