xml是實現不同語言或程序之間進行數據交換的協議，跟json差不多，但json使用起來更簡單，不過，古時候，在json還沒誕生的黑暗年代，大家只能選擇用xml呀，至今很多傳統公司如金融行業的很多系統的接口還主要是xml。

一、xml格式如下，就是通過<>節點來區別數據結構的

 1 <?xml version="1.0"?>
 2 <data>
 3     <country name="Liechtenstein">
 4         <rank updated="yes">2</rank>
 5         <year>2008</year>
 6
 
         <gdppc>141100</gdppc>
 7         <neighbor name="Austria" direction="E"/>
 8         <neighbor name="Switzerland" direction="W"/>
 9     </country>
10     <country name="Singapore">
11         <rank updated="yes">5</rank>
12         <year>2011</year>
13
 
         <gdppc>59900</gdppc>
14         <neighbor name="Malaysia" direction="N"/>
15     </country>
16     <country name="Panama">
17         <rank updated="yes">69</rank>
18         <year>2011</year>
19         <gdppc>13600</gdppc>
20         <neighbor name="
 
Costa Rica" direction="W"/>
21         <neighbor name="Colombia" direction="E"/>
22     </country>
23 </data>

二、xml協議在各個語言裏都是支持的，在python中可以用以下模塊操作xml

• 1、遍歷文檔和節點

 1 import xml.etree.ElementTree as ET
 2 tree = ET.parse("xml test.xml")#打開xml文件
 3 root = tree.getroot()#f.seek
 4 print(root.tag)  # =>data，打印tag標簽
 5 # 遍歷xml文檔
 6 for child in root:
 7     print(child.tag,child.attrib)
 8     for i in child:
 9         print(i.tag,i.text)
10 
11 # 只遍歷year節點
12 for node in root.iter(‘year‘):
13     print(node.tag,node.text)

• 2、修改和刪除xml的內容

 1 import xml.etree.ElementTree as ET
 2 tree = ET.parse("xml test.xml")
 3 root = tree.getroot()
 4 #修改
 5 for node in root.iter(‘year‘):
 6     new_year = int(node.text)+1
 7     node.text = str(new_year)
 8     node.set("updated","yes")
 9 tree.write("xml test.xml")
10 
11 #刪除
12 for country in root.findall("country"):
13     rank = int(country.find(‘rank‘).text)
14     if rank > 50:
15         root.remove(country)
16 tree.write("output.xml")

• 3、自己創建xml文件

 1 #自己創建xml文檔
 2 import xml.etree.ElementTree as ET
 3 new_xml = ET.Element("namelist")
 4 name = ET.SubElement(new_xml,"name",attrib={"enrolled":"yes"})
 5 age = ET.SubElement(name,"age",attrib={"checked":"no"})
 6 sex = ET.SubElement(name,"sex")
 7 sex.text = ‘33‘
 8 name2 = ET.SubElement(new_xml,"name",attrib={"enrolled":"no"})
 9 age = ET.SubElement(name2,"age")
10 age.text = ‘19‘
11 et = ET.ElementTree(new_xml) #生成文檔對象
12 et.write("test.xml", encoding="utf-8",xml_declaration=True)
13 ET.dump(new_xml) #打印生成的格式

xml模塊