一、前言

本节是修改xml;同样方法也可修改arxml文件；主要使用LET.Element创建节点；

二、知识点

 1、专门用于格式化处理xml文件使其具有层级分明的缩进函数

#专门用于格式化处理xml文件使其具有层级分明的缩进

def indent( elem, level=0):

    i = "\n" + level * "  "

    if len(elem):

        if not elem.text or not elem.text.strip():

            elem.text = i + "  "

        if not elem.tail or not elem.tail.strip():

            elem.tail = i

        for elem in elem:

            indent(elem, level + 1)

        if not elem.tail or not elem.tail.strip():

            elem.tail = i

    else:

        if level and (not elem.tail or not elem.tail.strip()):

            elem.tail = i

2、修改XML文件

#举例1：添加节点'country'

import lxml.etree as LET

tree = LET.parse('country_data.xml')

root = tree.getroot()

"""

country_ref = LET.Element("neighbor")

country_ref.attrib['name'] = 'china'

country =root.findall('country')

print(country)

country[0].append(country_ref)

indent(root)

tree.write("d:/myself/write_arxml/country_data.xml", xml_declaration=True, encoding='utf-8')

"""

#alt+shift+A  整段注销

3、修改节点rank文本值，添加属性

#举例2：修改节点rank文本值，添加属性

"""

for rank in root.iter('rank'):

    new_rank = int(rank.text) + 1

    rank.text = str(new_rank)

    rank.set('updated', 'yes')

tree.write('output.xml')

 """

4、删除节点

#举例3 删除节点

"""

for country in root.findall('country'):

    # using root.findall() to avoid removal during traversal

    rank = int(country.find('rank').text)

    if rank > 50:

        root.remove(country)

tree.write('output.xml')

 """

5、 构建 XML 文档

#知识点4：构建 XML 文档¶

""" a = LET.Element('a')

b = LET.SubElement(a, 'b')

c = LET.SubElement(a, 'c')

d = LET.SubElement(c, 'd')

LET.dump(a) #Writes an element tree or element structure to sys.stdout.

 """

三、实例 代码

import lxml.etree as LET
#专门用于格式化处理xml文件使其具有层级分明的缩进
def indent( elem, level=0):
    i = "\n" + level * "  "
    if len(elem):
        if not elem.text or not elem.text.strip():
            elem.text = i + "  "
        if not elem.tail or not elem.tail.strip():
            elem.tail = i
        for elem in elem:
            indent(elem, level + 1)
        if not elem.tail or not elem.tail.strip():
            elem.tail = i
    else:
        if level and (not elem.tail or not elem.tail.strip()):
            elem.tail = i
#alt+shift+A  整段注销
#可以通过从文件中读取来导入此数据：
tree = LET.parse('country_data.xml')
root = tree.getroot()
#可以迭代的子节点
""" for child in root:
    print(child.tag, child.attrib) """
#子级是可以嵌套的，我们可以通过索引访问特定的子级节点
""" print(root[0][2].text) """
#递归遍历其下的所有子树（包括子级，子级的子级，等等）

""" for neighbor in root.iter('neighbor'):
    print(neighbor.attrib) """
print("find:===============")
""" for neighbor in root.findall('neighbor'):
    #rank = country.find('rank').text
    #name = country.get('name')
    print(neighbor.attrib) """
    
    #print(name, rank)
""" for neighbor in root.xpath('country'):
    print(neighbor.attrib)
    test = neighbor.getparent().find('rank').text
    print(test) """
country_ref = LET.Element("neighbor")
country_ref.attrib['name'] = 'china'

country =root.findall('country')
print(country)
country[0].append(country_ref)
indent(root)
tree.write("d:/myself/write_arxml/country_data.xml", xml_declaration=True, encoding='utf-8')

四、运行代码后

五、测试用 xml文件

<?xml version='1.0' encoding='UTF-8'?>
<data>
  <country name="Liechtenstein">
    <rank>1</rank>
    <year>2008</year>
    <gdppc>141100</gdppc>
    <neighbor name="Austria" direction="E"/>
    <neighbor name="Switzerland" direction="W"/>
  </country>
  <country name="Singapore">
    <rank>4</rank>
    <year>2011</year>
    <gdppc>59900</gdppc>
    <neighbor name="Malaysia" direction="N"/>
  </country>
  <country name="Panama">
    <rank>68</rank>
    <year>2011</year>
    <gdppc>13600</gdppc>
    <neighbor name="Costa Rica" direction="W"/>
    <neighbor name="Colombia" direction="E"/>
  </country>
</data>