Python对XML文件实现增删改查操作

时间:2022-11-12 Septieme 人气:0

PYTHON 操作 XML

读取XML文件

关于XML的介绍

<data> 与 </data> 是一对标签的开始与结束

<property … /> 也是一个正确的标签，以 /> 结尾，是在标签没有嵌套内容时的简写形式

name=“cat”，name是<data>标签的一个属性，cat是name属性的值

description here …是<data>标签的内容，这里是一段文本。当然也可以是xml的嵌套

<data name="cat" num="10"> description here ... </data>

<property value="node" />

<country name="china">
	<province name="beijing">
		<school name="the sunshine school" />
	</province>
</country>

准备一个demo.xml文件

<data>
    <teacher name="Albert">
        <birthday>1980</birthday>
        <gender>male</gender>
        <subject>Math</subject>
    </teacher>

    <student name="Becky">
        <birthday>2000</birthday>
        <gender>female</gender>
        <hobbies>
            <hobby>skating</hobby>
            <hobby>rocks</hobby>
        </hobbies>
        <exam absence="no">
            <math>90</math>
            <english>90</english>
            <music>95</music>
        </exam>

    </student>
    <student name="Cindy">
        <birthday>2001</birthday>
        <gender>female</gender>
        <hobbies>
            <hobby>reading</hobby>
            <hobby>guitar</hobby>
        </hobbies>
        <exam absence="yes">
        </exam>
    </student>

    <student name="Duke">
        <birthday>2000</birthday>
        <gender>male</gender>
        <hobbies>
            <hobby>football</hobby>
            <hobby>surfing</hobby>
        </hobbies>
        <exam absence="no">
            <math>100</math>
            <english>80</english>
            <music>92</music>
        </exam>
    </student>

</data>

读取xml文件内容

# Read the .xml file
tree = ET.parse("demo.xml")
root = tree.getroot()
print(root)

结果

<Element 'data' at 0x102d80cf8>

遍历XML元素

for … in … 可以遍历当前元素的所有直接子节点

for n in root:
    # items() returns all <key, value> pairs of the tag
    print(n, n.tag , n.attrib, n.items())

结果

(<Element 'teacher' at 0x1048b9e48>, 'teacher', {'name': 'Albert'}, [('name', 'Albert')])
(<Element 'student' at 0x1048bf0f0>, 'student', {'name': 'Becky'}, [('name', 'Becky')])
(<Element 'student' at 0x1048bf3c8>, 'student', {'name': 'Cindy'}, [('name', 'Cindy')])
(<Element 'student' at 0x1048bf5f8>, 'student', {'name': 'Duke'}, [('name', 'Duke')])

想要迭代遍历当前元素的所有子节点（包括子孙节点）

for n in root.iter():
    print(n, n.tag)

结果

(<Element 'data' at 0x1052f0cf8>, 'data')
(<Element 'teacher' at 0x1052f0e48>, 'teacher')
(<Element 'birthday' at 0x1052f0d30>, 'birthday')
(<Element 'gender' at 0x1052f6080>, 'gender')
(<Element 'subject' at 0x1052f60b8>, 'subject')
(<Element 'student' at 0x1052f60f0>, 'student')
(<Element 'birthday' at 0x1052f6048>, 'birthday')
(<Element 'gender' at 0x1052f6128>, 'gender')
(<Element 'hobbies' at 0x1052f6198>, 'hobbies')
(<Element 'hobby' at 0x1052f6208>, 'hobby')
(<Element 'hobby' at 0x1052f6240>, 'hobby')
(<Element 'exam' at 0x1052f62b0>, 'exam')
(<Element 'math' at 0x1052f6320>, 'math')
(<Element 'english' at 0x1052f6390>, 'english')
(<Element 'music' at 0x1052f6400>, 'music')
(<Element 'student' at 0x1052f63c8>, 'student')
(<Element 'birthday' at 0x1052f6438>, 'birthday')
(<Element 'gender' at 0x1052f6470>, 'gender')
(<Element 'hobbies' at 0x1052f64a8>, 'hobbies')
(<Element 'hobby' at 0x1052f6518>, 'hobby')
(<Element 'hobby' at 0x1052f6588>, 'hobby')
(<Element 'exam' at 0x1052f65c0>, 'exam')
(<Element 'student' at 0x1052f65f8>, 'student')
(<Element 'birthday' at 0x1052f6630>, 'birthday')
(<Element 'gender' at 0x1052f6668>, 'gender')
(<Element 'hobbies' at 0x1052f66a0>, 'hobbies')
(<Element 'hobby' at 0x1052f6710>, 'hobby')
(<Element 'hobby' at 0x1052f6780>, 'hobby')
(<Element 'exam' at 0x1052f67b8>, 'exam')
(<Element 'math' at 0x1052f6828>, 'math')
(<Element 'english' at 0x1052f6898>, 'english')
(<Element 'music' at 0x1052f6908>, 'music')

想要选择性地迭代直接子节点

for n in root.iter('teacher'):
    print(n, n.tag)

(<Element 'teacher' at 0x100f29e48>, 'teacher')

查找XML元素

find与findall查找xml元素

# find the first element
print(root.find('student'))
# find all  elements
print(root.findall('student'))

<Element 'student' at 0x1034300f0>

[<Element 'student' at 0x1034300f0>, <Element 'student' at 0x1034303c8>, <Element 'student' at 0x1034305f8>]

demo

for n in root:
    if n.tag == 'student' and n.get('name') == 'Becky':
        exam_node = n.find('exam')
        for subject in exam_node:
            print(subject.tag + " " + subject.text)

结果

math 90
english 90
music 95

添加XML元素

p = ET.Element(tag_name)

demo

for n in root:
    if n.tag == 'student' and n.get('name') == 'Cindy':
        exam_node = n.find('exam')
        exam_node.set("absence", "no")
        for subject in ['math', 'music']:
            p = ET.Element(subject)
            p.text = '90'
            exam_node.append(p)

if os.path.exists('new.xml'):
    os.remove('new.xml')
tree.write('new.xml', encoding='utf-8', xml_declaration=True)

结果

<student name="Cindy">
<birthday>2001</birthday>
<gender>female</gender>
<hobbies>
<hobby>reading</hobby>
<hobby>guitar</hobby>
</hobbies>
<exam absence="no">
<math>90</math><music>90</music></exam>
</student>

修改XML元素

demo

for n in root:
    if n.tag == 'student' and n.get('name') == 'Cindy':
        exam_node = n.find('exam')
        exam_node.set("absence", "no")
        exam_node.set("date", "2022-11-11")
        for subject in ['math', 'music']:
            p = ET.Element(subject)
            p.text = '90'
            exam_node.append(p)

        hobbies_node = n.find('hobbies').findall("hobby")
        hobbies_node[0].text = 'piano'
        p = ET.Element("hobby")
        p.set("old_hobby", 'yes')
        p.text = 'reading'
        n.find('hobbies').remove(hobbies_node[1])
        n.find('hobbies').append(p)

结果

<student name="Cindy">
<birthday>2001</birthday>
<gender>female</gender>
<hobbies>
<hobby>piano</hobby>
<hobby old_hobby="yes">reading</hobby></hobbies>
<exam absence="no" date="2022-11-11">
<math>90</math><music>90</music></exam>
</student>

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