python入门：常用模块—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

xml的格式如下，就是通过<>节点来区别数据结构的:

<data>
    <country name="Liechtenstein">
        <rank updated="yes">2</rank>
        <year updated="yes">2010</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">2013</year>
        <gdppc>59900</gdppc>
        <neighbor direction="N" name="Malaysia" />
    </country>
    <country name="Panama">
        <rank updated="yes">69</rank>
        <year updated="yes">2013</year>
        <gdppc>13600</gdppc>
        <neighbor direction="W" name="Costa Rica" />
        <neighbor direction="E" name="Colombia" />
    </country>
</data>

　　xml协议在各个语言里的都 是支持的，在python中可以用以下模块操作xml

import xml.etree.ElementTree as ET

tree = ET.parse("xmltest.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)

# 遍历year节点
for node in root.iter('year'):
    print(node.tag, node.text)

# 修改和删除xml文档内容
# 修改
for node in root.iter('year'):
    new_year = int(node.text) + 1
    node.text = str(new_year)
    node.set('updated', 'yes')
tree.write("xmltest.xml")

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

　　自己创建xml文档

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