python基础第六篇

python基础 （五）模块篇2

真心觉得python这门语言是业界良心：

• shelve模块
• xml处理
• configparser模块
• hashlib模块
• logging模块

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一、shelve模块

shelve模块可以持久化任何pickle可支持的python数据格式，仅通过简单的key-value模式。

常规持久化：

#将创建好的类、列表、字典、时间戳等持久化#运行后自动创建shelve_bak,shelve_dat,shelve_dirimport shelveimport datetimed=shelve.open("shelve_test")info={"age":21,"job":"it"}age=[12,53,64]#创建一个类class staff(object):    def __init__(self,name):        self.name=name#开始持久化s1=staff("xzx")s2=staff("mm")d["info"]=infod["age"]=aged["s1"]=s1d["s2"]=s2d["date"]=datetime.datetime.now()d.close()

常规读取持久化后的文件

#和pickle反序列化一样，对函数及类序列化，其定义和创建过程必须给出，因为当初创建函数和类后，内存中就抹去了，序列化文件中储存的只不过是一个内存地址，相当于空头支票class staff(object):    def __init__(self,name):        self.name=name#打开文件d1=shelve.open("shelve_test")#shelve的文件手柄d1具有的items,keys,values方法返回的都是迭代器for i in d1.items():    print(i)#读取s1.nameprint(d1.get("s1").name)

输出结果：

#列出所有持续化数据('name', {'alex', 'rain', 'test'})('info', {'age': 21, 'job': 'it'})('date', datetime.datetime(2017, 9, 11, 11, 55, 46, 795584))('age', [12, 53, 64])('s1', <__main__.staff object at 0x7f99f664ae10>)('s2', <__main__.staff object at 0x7f99f6405ac8>)#读取s1.name结果xzx

二、 xml处理模块

xml是实现不同语言或程序之间进行数据交换的协议。现如今还剩了一些传统公司还在用xml，大家都转用json了。

下面是一个xml实例：

<?xml version="1.0"?><data>    <country name="Liechtenstein">        <rank updated="yes">2</rank>        <year>2008</year>        <gdppc>141100</gdppc>        <neighbor name="Austria" direction="E"/>        <neighbor name="Switzerland" direction="W"/>    </country>    <country name="Singapore">        <rank updated="yes">5</rank>        <year>2011</year>        <gdppc>59900</gdppc>        <neighbor name="Malaysia" direction="N"/>    </country>    <country name="Panama">        <rank updated="yes">69</rank>        <year>2011</year>        <gdppc>13600</gdppc>        <neighbor name="Costa Rica" direction="W"/>        <neighbor name="Colombia" direction="E"/>    </country></data>

xml协议在各个语言都是支持的，下面举例利用python中的xml模块来处理xml文件：

import xml.etree.ElementTree as ETtree=ET.parse("location.xml")root=tree.getroot()#tag是节点的名称print(root.tag)#所有节点的name，attrib,text和tail,tail是结尾文本for child in root:    for son in child:        print(son.tag,son.attrib,son.text,son.tail)

输出结果：

country {'name': 'Liechtenstein'}              rank {'updated': 'yes'} 2 dfgfdhgh        year {} 2008         gdppc {} 141100     country {'name': 'Singapore'}             rank {'updated': 'yes'} 5         year {} 2011         gdppc {} 59900     country {'name': 'Panama'}      rank {'updated': 'yes'} 69        year {} 2011        gdppc {} 13600 

修改和删除xml文档内容：

import xml.etree.ElementTree as ETtree=ET.parse("xmltest.xml")root=tree.getroot()#修改：#所有的year.text加1for node in root.iter("year"):    new_year=int(node.text)+1    node.text=str(new_year)    node.set("updated by","xmm")#给节点添加attrib属性#将tree写到新文件中去，注意不能覆盖原文件，覆盖后原文件不能打开tree.write("output.xml")#删除：for country in root.findall("country"):    rank=int(country.findtext("rank"))    if rank>50:        root.remove(country)        tree.write("newnew.xml")

自己创建xml文件，其实自己创建这个干嘛，了解下吧

import xml.etree.ElementTree as ETnew_xml=ET.Element("personinfolist")personinfo=ET.SubElement(new_xml,"personinfo",attrib={"enrolled":"yes"})age=ET.SubElement(personinfo,"age",attrib={"checked":"no"})sex=ET.SubElement(personinfo,"sex")sex.text="33"personinfo2=ET.SubElement(new_xml,"personinfo",attrib={"enrolled":"no"})name=ET.SubElement(personinfo2,"name")name.text="xmm"et=ET.ElementTree(new_xml)# 输入树的节点，攒成一棵树et.write("test.xml",encoding="utf-8",xml_declaration=True)ET.dump(new_xml)

输出结果：

<?xml version='1.0' encoding='utf-8'?><personinfolist>    <personinfo enrolled="yes">        <age checked="no" />        <sex>33</sex>    </personinfo>    <personinfo enrolled="no">        <name>xmm</name>    </personinfo></personinfolist>

三、configparser模块

用于生成和修改常见配置文档，下面为一个配置文档实例。

#配置文件：example.ini[DEFAULT]severaliveinterval = 45compression = yescompressionlevel = 9forwardx11 = yes[bitbucket.org]user = hg[tosecret.server.com]host port = 50022forwardx11 = no

这样一个文档可以由以下操作生成。

import configparserconfig=configparser.ConfigParser()config["DEFAULT"]={"SeverAliveInterval":"45","Compression":"yes","CompressionLevel":"9"}config["bitbucket.org"]={}config["bitbucket.org"]["User"]="hg"config["tosecret.server.com"]={}topsecret=config["tosecret.server.com"]topsecret["Host Port"]="50022"topsecret["forwardx11"]="no"config["DEFAULT"]["Forwardx11"]="yes"with open("example.ini","w") as configfile:    config.write(configfile)

读取配置文件操作：

import configparserconf=configparser.ConfigParser()print(conf.read("example.ini"))#判断能否读取.ini文件，若能读取返回该文件名print(conf.sections())#返回小节名，不包括[DEFAULT]print(conf.default_section)print(conf.defaults())print(conf.has_section("bitbucket.org"))print(conf.options("bitbucket.org"))print(conf.get("bitbucket.org","user"))sec=conf.remove_section("bitbucket.org")#判断有无sectionsprint(sec)with open("examle.cfg","w") as cfgfile:    conf.write(cfgfile)

四 、hashlib模块

用于加密相关的操作，主要提供 SHA1, SHA224, SHA256, SHA384, SHA512 ，MD5 算法

1、md5

import hashlibm=hashlib.md5()m.update(b"hello")print(m.hexdigest())m.update(b"easy go,if my body was on fire")print(m.hexdigest())m.update(b"you are a liar")print(m.hexdigest())#cefe459f41c025b72cfb1b9c65950a33m2=hashlib.md5()m2.update(b"helloeasy go,if my body was on fireyou are a liar")print(m2.hexdigest())#加密是不断拼接的过程#cefe459f41c025b72cfb1b9c65950a33

2、sha1

hash = hashlib.sha1()hash.update('admin')print(hash.hexdigest())

3、sha256

hash = hashlib.sha256()hash.update('admin')print(hash.hexdigest())

python中还有一个hmac模块，散列消息鉴别码，简称HMAC，是一种基于消息鉴别码MAC（Message Authentication Code）的鉴别机制。

五 、logging模块

python的logging模块提供了标准的日志接口，可以存储各种格式的日志，logging的日志可以分为debug(),info(),warning(),critical()5个级别。基本用法如下：

import logginglogging.warning("user [mm] attempted wrong more than 3 times")logging.critical("server is down")

输出：

WARNING:root:user [mm] attempted wrong more than 3 timesCRITICAL:root:server is down

级别 用处 debug 打印全部的日志(notset等同于debug) info 打印info,warning,error,critical级别的日志 warning 打印warning,error,critical级别的日志 error 打印error,critical级别的日志 critical 打印critical级别

也可以把日志写到文件里：

其中下面这句中level=loggin.INFO意思，把日志记录级别设置为INFO，只有日志是INFO或INFO级别更高的日志

logging.basicConfig(filename='example.log',level=logging.INFO,format="%(asctime)s %(message)s",datefmt="%m%d%Y %I:%M:%S %p")logging.debug('This message should go to the log file')logging.info('so should this')logging.warning('And this too')

日志格式：

format interpretation %(name)s Name of the logger (logging channel). %(levelno)s Numeric logging level for the message (DEBUG, INFO, WARNING, ERROR, CRITICAL). %(levelname)s Text logging level for the message (‘DEBUG’, ‘INFO’, ‘WARNING’, ‘ERROR’, ‘CRITICAL’). %(pathname)s Full pathname of the source file where the logging call was issued (if available). %(filename)s Filename portion of pathname. %(module)s Module (name portion of filename). %(funcName)s Name of function containing the logging call. %(lineno)d Source line number where the logging call was issued (if available). %(created)f Time when the LogRecord was created (as returned by time.time()). %(relativeCreated)d Time in milliseconds when the LogRecord was created, relative to the time the logging module was loaded. %(asctime)s Human-readable time when the LogRecord was created. By default this is of the form “2003-07-08 16:49:45,896” (the numbers after the comma are millisecond portion of the time). %(msecs)d Millisecond portion of the time when the LogRecord was created. %(thread)d Thread ID (if available). %(threadName)s Thread name (if available). %(process)d Process ID (if available). %(message)s The logged message, computed as msg % args.