python开发_xml.etree.ElementTree_XML文件操作_该模块在操作XML数据是存在安全隐患_慎用

2019年5月19日 163次阅读来源: Hongten

xml.etree.ElementTree模块实现了一个简单而有效的用户解析和创建XML数据的API。

在python3.3版本中，该模块进行了一些修改：

xml.etree.cElementTree模块被弃用。

警告：xml.etree.ElementTree模块在解析恶意构造的数据会产生一定的安全隐患。所以使用该模块的时候需要谨慎。

下面来看看该模块是怎样解析和创建XML数据文档的。

首先，我们应该了解一下什么是XML树和元素，XML是一种固有的层次化数据格式，这是一种最自然的格式类表示一棵树。

xml.etree.ElementTree（简写ET）就此而言，ElementTree代表的是整个XML无奈的和元素的一棵树，这棵树有一个唯一的

root根节点。在根节点下面，可以有很多子节点，而每一个子节点又可以有自己的属性或子节点….

我们今天需要解析的XML文件的内容如下：

我把该XML文件保存在：c:\\test\\hongten.xml文件中

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <students>
 3     <student no="2009081097">
 4         <name>Hongten</name>
 5         <gender>M</gender>
 6         <age>20</age>
 7         <score subject="math">97</score>
 8         <score subject="chinese">90</score>
 9     </student>
10     <student no="2009081098">
11         <name>DuDu</name>
12         <gender>W</gender>
13         <age>21</age>
14         <score subject="math">87</score>
15         <score subject="chinese">96</score>
16     </student>
17     <student no="2009081099">
18         <name>Sum</name>
19         <gender>M</gender>
20         <age>19</age>
21         <score subject="math">64</score>
22         <score subject="chinese">98</score>
23     </student>
24 </students>

在上面的XML文件内容中，我们可以看到此XML文件的根节点为：students
我们可以通过下面的方法获取到根节点：

1 import xml.etree.ElementTree as ET
2 tree = ET.parse('c:\\test\\hongten.xml')
3 root = tree.getroot()
4 tag = root.tag          #students

同样的我们也可以获取到根节点的属性：

1 attrib = root.attrib     #{}

因为根节点：students是没有属性的，所以为空。

我们要获取根节点：students的子节点名称和属性：

1  for child in root:
2      print(child.tag, child.attrib)

输出为：

student {'no' : '2009081097'}
student {'no' : '2009081098'}
student {'no' : '2009081099'}

我们同样可以获取属性对应的值：

1 for student in root.findall('student'):
2     no = student.get('no')
3     name = student.find('name').text
4     print(no, name)

输出为：

2009081097 Hongten
2009081098 DuDu
2009081099 Sum

当然，我们也可以修改XML文件的内容：

1 for age in root.iter('age'):
2     new_age = int(age.text) + 1
3     age.text = str(new_age)
4     age.set('updated', 'yes')
5 tree.write('c:\\test\\hongten_update.xml')

修改后的XML文件内容如下：

 1 <students>
 2     <student no="2009081097">
 3         <name>Hongten</name>
 4         <gender>M</gender>
 5         <age updated="yes">21</age>
 6         <score subject="math">97</score>
 7         <score subject="chinese">90</score>
 8     </student>
 9     <student no="2009081098">
10         <name>DuDu</name>
11         <gender>W</gender>
12         <age updated="yes">22</age>
13         <score subject="math">87</score>
14         <score subject="chinese">96</score>
15     </student>
16     <student no="2009081099">
17         <name>Sum</name>
18         <gender>M</gender>
19         <age updated="yes">20</age>
20         <score subject="math">64</score>
21         <score subject="chinese">98</score>
22     </student>
23 </students>

==================================================================

以下是我对xml.etree.ElementTree模块进行了一些封装

==================================================================

  1 # -*- coding: utf-8 -*-
  2 #python xml.etree.ElementTree
  3 
  4 #Author   :   Hongten
  5 #Mailto   :   hongtenzone@foxmail.com
  6 #Blog     :   http://www.cnblogs.com/hongten
  7 #QQ       :   648719819
  8 #Version  :   1.0
  9 #Create   :   2013-09-03
 10 
 11 import os
 12 import xml.etree.ElementTree as ET
 13 
 14 '''
 15     在python中，解析XML文件有很多中方法
 16     本文中要使用的方法是：xml.etree.ElementTree       
 17 '''
 18 #global var
 19 #show log
 20 SHOW_LOG = True
 21 #XML file
 22 XML_PATH = None
 23 
 24 def get_root(path):
 25     '''parse the XML file,and get the tree of the XML file
 26     finally,return the root element of the tree.
 27     if the XML file dose not exist,then print the information'''
 28     if os.path.exists(path):
 29         if SHOW_LOG:
 30             print('start to parse the file : [{}]'.format(path))
 31         tree = ET.parse(path)
 32         return tree.getroot()
 33     else:
 34         print('the path [{}] dose not exist!'.format(path))
 35 
 36 def get_element_tag(element):
 37     '''return the element tag if the element is not None.'''
 38     if element is not None:
 39         if SHOW_LOG:
 40             print('begin to handle the element : [{}]'.format(element))
 41         return element.tag
 42     else:
 43         print('the element is None!')
 44 
 45 def get_element_attrib(element):
 46     '''return the element attrib if the element is not None.'''
 47     if element is not None:
 48         if SHOW_LOG:
 49             print('begin to handle the element : [{}]'.format(element))
 50         return element.attrib
 51     else:
 52         print('the element is None!')
 53 
 54 def get_element_text(element):
 55     '''return the text of the element.'''
 56     if element is not None:
 57         return element.text
 58     else:
 59         print('the element is None!')
 60 
 61 def get_element_children(element):
 62     '''return the element children if the element is not None.'''
 63     if element is not None:
 64         if SHOW_LOG:
 65             print('begin to handle the element : [{}]'.format(element))
 66         return [c for c in element]
 67     else:
 68         print('the element is None!')
 69 
 70 def get_elements_tag(elements):
 71     '''return the list of tags of element's tag'''
 72     if elements is not None:
 73         tags = []
 74         for e in elements:
 75             tags.append(e.tag)
 76         return tags
 77     else:
 78         print('the elements is None!')
 79 
 80 def get_elements_attrib(elements):
 81     '''return the list of attribs of element's attrib'''
 82     if elements is not None:
 83         attribs = []
 84         for a in elements:
 85             attribs.append(a.attrib)
 86         return attribs
 87     else:
 88         print('the elements is None!')
 89 
 90 def get_elements_text(elements):
 91     '''return the dict of element'''
 92     if elements is not None:
 93         text = []
 94         for t in elements:
 95             text.append(t.text)
 96         return dict(zip(get_elements_tag(elements), text))
 97     else:
 98         print('the elements is None!')
 99 
100 def init():
101     global SHOW_LOG
102     SHOW_LOG = True
103     global XML_PATH
104     XML_PATH = 'c:\\test\\hongten.xml'
105 
106 def main():
107     init()
108     #root
109     root = get_root(XML_PATH)
110     root_tag = get_element_tag(root)
111     print(root_tag)
112     root_attrib = get_element_attrib(root)
113     print(root_attrib)
114     #children
115     children = get_element_children(root)
116     print(children)
117     children_tags = get_elements_tag(children)
118     print(children_tags)
119     children_attribs = get_elements_attrib(children)
120     print(children_attribs)
121 
122     print('#' * 50)
123     #获取二级元素的每一个子节点的名称和值
124     for c in children:
125         c_children = get_element_children(c)
126         dict_text = get_elements_text(c_children)
127         print(dict_text)
128     
129 if __name__ == '__main__':
130     main()

运行效果：

Python 3.3.2 (v3.3.2:d047928ae3f6, May 16 2013, 00:03:43) [MSC v.1600 32 bit (Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> ================================ RESTART ================================
>>> 
start to parse the file : [c:\test\hongten.xml]
begin to handle the element : [<Element 'students' at 0x0215C5A0>]
students
begin to handle the element : [<Element 'students' at 0x0215C5A0>]
{}
begin to handle the element : [<Element 'students' at 0x0215C5A0>]
[<Element 'student' at 0x0215C600>, <Element 'student' at 0x0215C750>, <Element 'student' at 0x0215C870>]
['student', 'student', 'student']
[{'no': '2009081097'}, {'no': '2009081098'}, {'no': '2009081099'}]
##################################################
begin to handle the element : [<Element 'student' at 0x0215C600>]
{'score': '90', 'gender': 'M', 'name': 'Hongten', 'age': '20'}
begin to handle the element : [<Element 'student' at 0x0215C750>]
{'score': '96', 'gender': 'W', 'name': 'DuDu', 'age': '21'}
begin to handle the element : [<Element 'student' at 0x0215C870>]
{'score': '98', 'gender': 'M', 'name': 'Sum', 'age': '19'}
>>>

========================================================