shelve模块和xml模块

shelve模块

shelve模块比pickle模块简单，只有一个open，返回类似字典的对象，可读可写：key必须为字符串，

而值可以是python所支持的数据类型

import shelve
f=shelve.open(r'shelve.txt')
 f['stu1_info']={'name':'egon','age':18,'hobby':['piao','smoking','drinking']}
 f['stu2_info']={'name':'gangdan','age':53}
 f['school_info']={'website':'http://www.pypy.org','city':'beijing'}
print(f['stu1_info']['hobby'])
f.close()

 xml模块

xml是实现不同语言或者程序之间进行数据交换的协议，跟json差不多，但是json使用起来更简单，不过、

，古时候，在json还没诞生的黑暗年代，大家只能选择用xml呀，至今很多传统公司如金融行业的很多系统

的接口还主要是xml

xml的格式如下，就是通过<>节点来区别数据结构的：

#==========================================>查
import xml.etree.ElementTree as ET
#
# tree=ET.parse('a.xml')
# root=tree.getroot()
#三种查找节点的方式
# res=root.iter('rank') # 会在整个树中进行查找，而且是查找到所有
# for item in res:
#     # print(item)
#     print('='*50)
#     print(item.tag) # 标签名
#     print(item.attrib) #属性
#     print(item.text) #文本内容


# res=root.find('country') # 只能在当前元素的下一级开始查找。并且只找到一个就结束
# print(res.tag)
# print(res.attrib)
# print(res.text)
# nh=res.find('neighbor')
# print(nh.attrib)


# cy=root.findall('country') # 只能在当前元素的下一级开始查找,
# print([item.attrib for item in cy])




#==========================================>改
# import xml.etree.ElementTree as ET
# tree=ET.parse('a.xml')
# root=tree.getroot()
#
# for year in root.iter('year'):
#     year.text=str(int(year.text) + 10)
#     year.attrib={'updated':'yes'}
#
#
# # tree.write('b.xml')
# tree.write('a.xml')



#==========================================>增
import xml.etree.ElementTree as ET
tree=ET.parse('a.xml')
root=tree.getroot()

for country in root.iter('country'):
    # print(country)
    year=country.find('year')
    # print(year)
    if int(year.text) > 2020:
        # print(country.attrib)
        # ele=ET.Element('egon')
        # ele.attrib={'nb':'yes'}
        # ele.text='非常帅'
        # country.append(ele)
        country.remove(year)
tree.write('b.xml')

自己创建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")
sex.text = '33'
name2 = ET.SubElement(new_xml,"name",attrib={"enrolled":"no"})
age = ET.SubElement(name2,"age")
age.text = '19'
 
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