xml是實現不同語言或程式之間進行資料交換的協議，跟json差不多，但json使用起來更簡單，不過，以前在json還沒誕生的時候，大家只能選擇用xml，至今很多傳統公司如金融行業的很多系統的介面還主要是xml。

xml的格式如下，就是通過<>節點來區別資料結構的:

<?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協議在各個語言裡的都是支援的，在python中可以用以下模組操作xml

import xml.etree.ElementTree as ET

tree = ET.parse('xmltest.xml')
root = tree.getroot()
print(root.tag) # data 根標籤

# 遍歷xml文件
for child in root:
    print(child.tag,child.attrib)
    for i in child:
        print(i.tag,i.text)

# 只遍歷year 節點
for node in root.iter('year'):
    print(node.tag,node.text)

# 修改
for node in root.iter('year'):
    new_year=int(node.text)+1 #加1
    node.text=str(new_year)
    node.set("updated","yes") #加屬性
tree.write('xmltest.xml')

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

自己建立xml文件

import xml.etree.ElementTree as ET

new_xml = ET.Element("infolist") #根節點

personinfo = ET.SubElement(new_xml,"personinfo",attrib={"enrolled":"yes"})
name = ET.SubElement(personinfo,'name')
name.text = 'Alice'
age = ET.SubElement(personinfo,'age',attrib={"check":"no"})
age.text = '21'
sex = ET.SubElement(personinfo,'sex')
sex.text = 'F'

personinfo2 = ET.SubElement(new_xml,"personinfo",attrib={"enrolled":"yes"})
name = ET.SubElement(personinfo2,'name')
name.text = 'Bob'
age = ET.SubElement(personinfo2,'age',attrib={"check":"no"})
age.text = '30'
sex = ET.SubElement(personinfo2,'sex')
sex.text = 'M'

et = ET.ElementTree(new_xml) # 生成文件物件
et.write("test.xml",encoding='UTF-8',xml_declaration=True)

ET.dump(new_xml)  # 列印生成的格式