python课堂整理27----xml 模块

一、概念

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更简单，不过xml出现太早，很多地方已广泛使用

tag: 标签  attrib:属性   text:内容

二、获取标签

import xml.etree.ElementTree as xm
tree = xm.parse("xml_lesson")
root = tree.getroot()
print(root.tag)  #得到跟标签，data
for i in root:   
    print(i.tag)  #遍历data 得到子标签 country
    for j in i: 
        print(j.tag)  #遍历country,得到country的子标签

三、获取属性

import xml.etree.ElementTree as xm
tree = xm.parse("xml_lesson")
root = tree.getroot()
print(root.tag)  #得到跟标签，data
for i in root:   #遍历data 得到country
    print(i.attrib)  #获得country 的属性
    for j in i:  #遍历country得到下面子标签
        print(j.attrib)  #获得下面子标签的属性

四、获取内容

import xml.etree.ElementTree as xm
tree = xm.parse("xml_lesson")
root = tree.getroot()
print(root.tag)  #得到跟标签，data
for i in root:   #遍历data 得到country
    for j in i:  #遍历country得到下面子标签
        print(j.text)  #获得下面子标签的内容

五、只遍历year标签

import xml.etree.ElementTree as xm
tree = xm.parse("xml_lesson")
root = tree.getroot()
for node in root.iter('year'):
    print(node.tag, node.text)  #获取year的标签和属性

 六、修改

import xml.etree.ElementTree as xm
tree = xm.parse("xml_lesson")
root = tree.getroot()
for node in root.iter('year'):
    new_year = int(node.text) + 1  #把year内容加1
    node.text = str(new_year)
    node.set("updata", "year")
tree.write("xml_lesson")  #覆盖掉原来的文件

七、删除

import xml.etree.ElementTree as xm
tree = xm.parse("xml_lesson")
root = tree.getroot()
for country in root.findall('Country'):
    rank = int(country.find('rank').text)
    if rank > 50:
        root.remove(country)  #把rank大于50的country删掉
tree.write("xml_lesson")

八、创建xml文件

import xml.etree.ElementTree as xm
new_xml = xm.Element("namelist")  #生成根
name = xm.SubElement(new_xml, "name", attrib = {"enrolled": "yes"})
age = xm.SubElement(name, "age", attrib = {"checked":"no"})
sex = xm.SubElement(name, "sex")
sex.text = "22"
name2 = xm.SubElement(new_xml, "name", attrib = {"enrolled": "no"})
age = xm.SubElement(name2, "age")
age.text = "19"

et = xm.ElementTree(new_xml)  #生成文档对象
et.write("text.xml", encoding = "utf -8", xml_declaration = True)
xm.dump(new_xml)  #打印生成的格式