常用文件类型 -- XML文件介绍_典型的xml文件类型

XML文件介绍

1.1 介绍

XML是一种数据存储、交换、表达的标准：

• 存储：优势在于半结构化，可以自定义schema，相比关系型二维表，不用遵循第一范式（可以有嵌套关系）；
• 交换：可以通过schema实现异构数据集成；
• 表达：本身就可以作为阅读文档，当然还可以使用XSLT之类的进行解析和再显示。

缺点是schema验证复杂，相比后来的json等格式，相对冗余,性能也不够优秀。但是作为半结构化文档的代表性标准，早期代表的是一种数据思想。

鉴于以上缺点，本人不对xml做过多研究，直接上封装的工具类。

1.2 封装工具类

from collections import defaultdict
import xml.etree.ElementTree as ET
from xml.etree.ElementTree import Element, ElementTree


class XML2Dict(object):
    def __init__(self, coding='UTF-8'):
        self._coding = coding
        self.remove_ns = False
        self.contains_attr = True
        self.attr_prefix = '@'

    def _parse_node(self, t):
        ttag = t.tag
        if self.remove_ns:
            ttag = self._remove_namespace(ttag)
        d = {ttag: {} if t.attrib else None}  # the variable 'd' is the constructed target dictionary
        # 't.tag' if have values, it is the first layer of the dictionary
        children = list(t)  # The following recursive traverse processing tree, until the leaf node
        if children:  # Determine whether the node is empty, recursive boundary conditions
            dd = defaultdict(list)
            for dc in map(self._parse_node, children):  # recursive traverse processing tree
                for k, v in dc.items():
                    dd[k].append(v)
            d = {ttag: {k: v[0] if len(v) == 1 else v for k, v in dd.items()}}  # handle child node
        if self.contains_attr:
            if t.attrib:  # handle attributes,prefix all of the stored attributes @
                # d[ttag].update(('@' + k, v) for k, v in t.attrib.items())
                d[ttag].update((self.attr_prefix + k, v) for k, v in t.attrib.items())
        if t.text.strip():
            # text = t.text.strip().encode(self._coding)  # strip blank space
            text = t.text.strip()  # strip blank space
            if children or t.attrib:
                d[ttag]['#text'] = text
            else:
                d[ttag] = text  # the text value as t.tag
        return d

    def parse(self, xml_file):
        with open(xml_file, 'r') as fp:
            return self.fromstring(fp.read())

    def fromstring(self, xml_str):
        # self.remove_ns = remove_namespace
        t = ET.fromstring(xml_str)
        return self._parse_node(t)

    def _remove_namespace(self, tag):
        if tag.find("{") >= 0 and tag.find("}") >= 0:
            return tag[:tag.find("{")] + tag[(tag.find("}") + 1):]
        else:
            return tag


class XMLHelper(object):

    @staticmethod
    def dict2xml(path, my_dict, root='root', encoding='utf8'):
        elem = Element(root)  # 使用Element创建元素
        # 循环key与val
        for key, val in my_dict.items():
            # 创建新的元素,确定元素的值
            child = Element(key)
            child.text = str(val)
            # 添加为elem的子节点
            elem.append(child)

        tree = ElementTree(elem)
        # 写成xml文件
        tree.write(path, encoding=encoding)

    @staticmethod
    def xml2dict(path, remove_ns=True, contains_attr=True, attr_prefix=''):
        x2d = XML2Dict()
        x2d.remove_ns = remove_ns
        x2d.contains_attr = contains_attr
        x2d.attr_prefix = attr_prefix
        return x2d.parse(path)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
'
运行
运行

1.3 工具类调用举例

• config.xml文件：

<?xml version="1.0" encoding="utf-8" ?>
<!-- This is list of customers -->
<customers>
  <customer ID="C001">
    <name>Acme Inc.</name>
    <phone>12345</phone>
    <comments>
      <![CDATA[Regular customer since 1995]]>
    </comments>
  </customer>
  <customer ID="C002">
    <name>Star Wars Inc.</name>
    <phone>23456</phone>
    <comments>
      <![CDATA[A small but healthy company.]]>
    </comments>
  </customer>
</customers>
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18

• 示例代码

from test_xml.XMLHelper import  XMLHelper


def demo():
    # 读取xml文件
    xml_path = 'config.xml'
    print(XMLHelper.xml2dict(xml_path))
    # {'customers': {'customer': [{'name': 'Acme Inc.', 'phone': '12345', 'comments': 'Regular customer since 1995', '@ID': 'C001'},
    # {'name': 'Star Wars Inc.', 'phone': '23456', 'comments': 'A small but healthy company.', '@ID': 'C002'}]}}

    # 将字典写入xml文件
    db_dict = {'user': 'zet', 'password': '123456'}
    XMLHelper.dict2xml('db.xml', db_dict, root='db')
1
2
3
4
5
6
7
8
9
10
11
12
13