----------------------------接 python内置模块（二）---------------------------

八、 shelve模块

     shelve模块是一个简单的k,v将内存数据通过文件持久化的模块，可以持久化任何pickle可支持的python数据格式，他只有一个函数就是open()，这个函数接收一个参数就是文件名，然后返回一个shelf

对象，你可以用他来存储东西，就可以简单的把他当作一个字典，当你存储完毕的时候，就调用close

函数来关闭。

>>> import shelve

>>> sfile = shelve.open('shelve_test')    # 打开一个文件

>>> sfile['k1'] = []               # 持久化存储列表

>>> sfile['k1']

[]

>>> sfile.close()                  # 文件关闭

九、 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，xml通过<>节点来区别数据结构的:

<?xml version="1.0"?>

遍历xml文档

import xml.etree.ElementTree as ET

tree = ET.parse("test.xml")

root = tree.getroot()

print(root.tag)

#遍历xml文档

for child in root:

print(child.tag, child.attrib)

for i in child:

print(i.tag,i.text)

#只遍历year 节点

for node in root.iter('year'):

print(node.tag,node.text)

修改xml文档

import xml.etree.ElementTree as ET

tree = ET.parse("test.xml")

for node in root.iter('year'):

new_year = int(node.text) + 1

node.text = str(new_year)

node.set("updated","yes")

tree.write("test.xml")

for node in root.iter('year'):

print(node.tag,node.text)

删除xml内容

#删除node

import xml.etree.ElementTree as ET

tree = ET.parse("test.xml")

for country in root.findall('country'):

rank = int(country.find('rank').text)

if rank > 50:

root.remove(country)

tree.write('test.xml')

for child in root:

print(child.tag, child.attrib)

for i in child:

print(i.tag,i.text)

创建xml文档

import xml.etree.ElementTree as ET

new_xml = ET.Element("namelist")

name = ET.SubElement(new_xml,"name",attrib={"enrolled":"yes"})

age = ET.SubElement(name,"age",attrib={"checked":"no"})

sex = ET.SubElement(name,"sex")

age.text = '33'

sex.text = 'F'

name2 = ET.SubElement(new_xml,"name",attrib={"enrolled":"no"})

age = ET.SubElement(name2,"age")

sex = ET.SubElement(name2,"sex")

age.text = '19'

sex.text = 'M'

et = ET.ElementTree(new_xml) #生成文档对象

et.write("test.xml", encoding="utf-8",xml_declaration=True)

ET.dump(new_xml) #打印生成的格式

        <namelist><name enrolled="yes"><age checked="no">33</age><sex>F</sex></name><name enrolled="no"><age>19</age><sex>M</sex></name></namelist>

十、 ConfigParser模块

用于生成和修改常见配置文档，当前模块的名称在 python 3.x 版本中变更为 configparser。

常见软件配置文档格式如下：

[DEFAULT]

       生成配置文件方法：

import configparser

config = configparser.ConfigParser()

config["DEFAULT"] = {}

config["DEFAULT"]['ServerAliveInterval']=  '45'

config["DEFAULT"]['Compression'] = 'yes'

config["DEFAULT"]['CompressionLevel'] = '9'

config['DEFAULT']['ForwardX11'] = 'yes'

config['bitbucket.org'] = {}

config['bitbucket.org']['User'] = 'hg'

config['topsecret.server.com'] = {}

config['topsecret.server.com']['Host Port'] = '50022'

config['topsecret.server.com']['ForwardX11'] = 'no'

with open('example.ini', 'w') as configfile:

config.write(configfile)

   从配置文件中读出内容：

import configparser

config = configparser.ConfigParser()

print(config.sections())

print(config.read('example.ini'))  //想要读取配置文件中内容需要先执行此操作将内容读进内存；

print(config.sections())

print(config['bitbucket.org']['User'])

for key in config['DEFAULT']:

print(key)

结果是：

[]

['example.ini']

['bitbucket.org', 'topsecret.server.com']

hg

serveraliveinterval

compression

compressionlevel

forwardx11

      configparser增删改查语法

import configparser

config = configparser.ConfigParser()

config.read('example.ini')

# ********* 读 *********

#secs = config.sections()

#print(secs)

#options = config.options('bitbucket.org') // 获取sections下所有key值

#print(options)

#item_list = config.items('bitbucket.org') // 获取sections下所有items

#print(item_list)

#val = config.get('bitbucket.org','user')  // 在sections 下找到某key值

#val = config.getint('bitbucket.org','compressionlevel') // 先get 后int，即将int类型的

字符串转换成int类型

#print(val)

# ********** 改写 ***********

#sec = config.remove_section('bitbucket.org')

#config.write(open('new_example.ini', "w"))

#secs = config.has_section('bitbucket')

#config.add_section('bitbucket')

#config.write(open('example.cfg', "w"))

#config.set('bitbucket.org','user','shuoming')

#config.write(open('new_example.cfg', "w"))

#config.remove_option('bitbucket.org','user')

#config.write(open('new_example.cfg', "w"))

----------------------------接 内置模块(四)---------------------------