XML处理

xmltest.xml内容如下：

<?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>

-------------------------------------------------------------
查找xml信息：

import xml.etree.ElementTree as ET
tree = ET.parse("xmltest.xml")
root = tree.getroot()
print(root)
print(root.tag) #最外面的标签名

# 遍历xml文档
for child in root:
    print(child.tag, child.attrib)#child.tag标签名，child.attrib 属性信息
    for i in child:
        print(i.tag, i.text)        #i.text，string对象，表示element的内容。
# 只遍历year 节点
for node in root.iter('year'):
    print(node.tag, node.text)

ElementTree提供的方法:

find(match)                                                    # 查找第一个匹配的子元素， match可以时tag或是xpaht路径
findall(match)                                              # 返回所有匹配的子元素列表
findtext(match, default=None)                     #查找匹配匹配的第一个子元素的文本
iter(tag=None)                                              # 以当前元素为根节点 创建树迭代器,如果tag不为None,则以tag进行过滤
iterfind(match)                                             #按标签名称或路径查找所有匹配的子元素。 返回一个迭代，以文档顺序生成所有匹配的元素.

-------------------------------------------------------------
修改xml

import xml.etree.ElementTree as ET

tree = ET.parse("xmltest.xml")
root = tree.getroot()   #返回此xml的根元素

# 修改
for node in root.iter('year'):
    new_year = int(node.text) + 1
    node.text = str(new_year)   #转换为str，因为int不是可迭代的
    node.set("updated", "yes")
    print(node.text)

tree.write("xmltest.xml")

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

tree.write('xmltest.xml')

-------------------------------------------------------------
创建xml:

import xml.etree.ElementTree as ET
new_xml = ET.Element("namelist")        #最外面的标签名
name = ET.SubElement(new_xml, "name", attrib={"enrolled": "yes"})#二级标签名name,属性enrolled="yes"；new_xml是父元素，name是子元素， attrib是一个可选字典，包含元素属性
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)#encoding是输出编码,xml_declaration控制是否应将XML声明添加到文件中，使用为True,不使用为False

ET.dump(new_xml)  # 打印生成的格式

参考：
https://www.cnblogs.com/alex3714/articles/5161349.html
https://docs.python.org/3/library/xml.etree.elementtree.html?highlight=findtext#xml.etree.ElementTree.Element.findtext