xml模块

　　xml是实现不同语言或程序之间进行数据交换的协议，跟json差不多，但json使用起来更简单，至今很多公司系统的接口还主要是xml。

　　xml格式如xml_test文件，通过<>节点来区别数据结构。

<data>
    <country name="Liechtenstein">
        <rank updated="yes">2</rank>
        <year updated="yes">2009</year>
        <gdppc>141100</gdppc>
        <neighbor direction="E" name="Austria" />
        <neighbor direction="W" name="Switzerland" />
    </country>
    <country name="Singapore">
        <rank updated="yes">5</rank>
        <year updated="yes">2012</year>
        <gdppc>59900</gdppc>
        <neighbor direction="N" name="Malaysia" />
    </country>
    <country name="Panama">
        <rank updated="yes">69</rank>
        <year updated="yes">2012</year>
        <gdppc>13600</gdppc>
        <neighbor direction="W" name="Costa Rica" />
        <neighbor direction="E" name="Colombia" />
    </country>
</data>

xml文档读取遍历

import xml.etree.ElementTree as ET

tree = ET.parse("xml_test")  # 打开文件
root = tree.getroot()  #
print(root)
# 输出：<Element 'data' at 0x1019b2a48>
print(root.tag)
# 输出：data


#遍历xml文档
for child in root:
    # print(child.tag, child.attrib)
    print('-------',child.tag,child.attrib)
    for i in child:
        print(i.tag,i.text)
"""
输出：------- country {'name': 'Liechtenstein'}
     rank 2
     year 2008
     gdppc 141100
     neighbor None
     neighbor None
"""

#只遍历year 节点
for node in root.iter('year'):
    print(node.tag,node.text)
"""
输出：year 2008
     year 2011
     year 2011
"""

xml增删改

import xml.etree.ElementTree as ET

tree = ET.parse("xml_test")
root = tree.getroot()   # f.seek(0)

# 修改
for node in root.iter('year'):
    new_year = int(node.text) + 1
    node.text = str(new_year)
    node.set("updated","yes")  # 添加属性

tree.write("xml_test")

# 删除node
for country in root.findall('country'):
    rank = int(country.find('rank').text)
    if rank > 50:
        root.remove(country)

tree.write('output.xml')

xml自动创建

import xml.etree.ElementTree as ET

root = ET.Element("namelist")  # root
name = ET.SubElement(root,"name",attrib={"enrolled":"yes"})  # 在root下创建name节点，内容为"enrolled":"yes"
age = ET.SubElement(name,"age",attrib={"checked":"no"})
sex = ET.SubElement(name,"sex")
sex.text = 'male'  # 性别

name2 = ET.SubElement(root,"name",attrib={"enrolled":"no"})
age = ET.SubElement(name2,"age")
age.text = '19'

et = ET.ElementTree(root) #生成文档对象

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

ET.dump(root) #打印生成的格式