python中使用Element操作xml

需求：

在实际应用中，需要对xml配置文件进行实时修改，

1.增加、删除 某些节点

2.增加，删除，修改某个节点下的某些属性

3.增加，删除，修改某些节点的文本

xml源文件格式[例]

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<?xml version="1.0" encoding="UTF-8"?>

<framework>

<processers>

<processer name="AProcesser" file="lib64/A.so"

path="/tmp">

</processer>

<processer name="BProcesser" file="lib64/B.so" value="fordelete">

</processer>

<processer name="BProcesser" file="lib64/B.so2222222"/>

<services>

<service name="search" prefix="/bin/search?"

output_formatter="OutPutFormatter:service_inc">

<chain sequency="chain1"/>

<chain sequency="chain2"></chain>

</service>

<service name="update" prefix="/bin/update?">

<chain sequency="chain3" value="fordelete"/>

</service>

</services>

</processers>

</framework>

使用库：

xml.etree.ElementTree

官方文档地址:http://docs.python.org/library/xml.etree.elementtree.html

实现思想：

使用ElementTree，先将文件读入，解析成树，之后，根据路径，可以定位到树的每个节点，再对节点进行修改，最后直接将其输出

代码附文档：

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#!/usr/bin/python

# -*- coding=utf-8 -*-

# author : wklken@yeah.net

# date: 2012-05-25

# version: 0.1

from xml.etree.ElementTree import ElementTree,Element

def read_xml(in_path):

'''''读取并解析xml文件

in_path: xml路径

return: ElementTree'''

tree = ElementTree()

tree.parse(in_path)

return tree

def write_xml(tree, out_path):

'''''将xml文件写出

tree: xml树

out_path: 写出路径'''

tree.write(out_path, encoding="utf-8",xml_declaration=True)

def if_match(node, kv_map):

'''''判断某个节点是否包含所有传入参数属性

node: 节点

kv_map: 属性及属性值组成的map'''

for key in kv_map:

if node.get(key) != kv_map.get(key):

return False

return True

#---------------search -----

def find_nodes(tree, path):

'''''查找某个路径匹配的所有节点

tree: xml树

path: 节点路径'''

return tree.findall(path)

def get_node_by_keyvalue(nodelist, kv_map):

'''''根据属性及属性值定位符合的节点，返回节点

nodelist: 节点列表

kv_map: 匹配属性及属性值map'''

result_nodes = []

for node in nodelist:

if if_match(node, kv_map):

result_nodes.append(node)

return result_nodes

#---------------change -----

def change_node_properties(nodelist, kv_map, is_delete=False):

'''''修改/增加 /删除 节点的属性及属性值

nodelist: 节点列表

kv_map:属性及属性值map'''

for node in nodelist:

for key in kv_map:

if is_delete:

if key in node.attrib:

del node.attrib[key]

else:

node.set(key, kv_map.get(key))

def change_node_text(nodelist, text, is_add=False, is_delete=False):

'''''改变/增加/删除一个节点的文本

nodelist:节点列表

text : 更新后的文本'''

for node in nodelist:

if is_add:

node.text += text

elif is_delete:

node.text = ""

else:

node.text = text

def create_node(tag, property_map, content):

'''''新造一个节点

tag:节点标签

property_map:属性及属性值map

content: 节点闭合标签里的文本内容

return 新节点'''

element = Element(tag, property_map)

element.text = content

return element

def add_child_node(nodelist, element):

'''''给一个节点添加子节点

nodelist: 节点列表

element: 子节点'''

for node in nodelist:

node.append(element)

def del_node_by_tagkeyvalue(nodelist, tag, kv_map):

'''''同过属性及属性值定位一个节点，并删除之

nodelist: 父节点列表

tag:子节点标签

kv_map: 属性及属性值列表'''

for parent_node in nodelist:

children = parent_node.getchildren()

for child in children:

if child.tag == tag and if_match(child, kv_map):

parent_node.remove(child)

if __name__ == "__main__":

#1. 读取xml文件

tree = read_xml("./test.xml")

#2. 属性修改

#A. 找到父节点

nodes = find_nodes(tree, "processers/processer")

#B. 通过属性准确定位子节点

result_nodes = get_node_by_keyvalue(nodes, {"name":"BProcesser"})

#C. 修改节点属性

change_node_properties(result_nodes, {"age": "1"})

#D. 删除节点属性

change_node_properties(result_nodes, {"value":""}, True)

#3. 节点修改

#A.新建节点

a = create_node("person", {"age":"15","money":"200000"}, "this is the firest content")

#B.插入到父节点之下

add_child_node(result_nodes, a)

#4. 删除节点

#定位父节点

del_parent_nodes = find_nodes(tree, "processers/services/service")

#准确定位子节点并删除之

target_del_node = del_node_by_tagkeyvalue(del_parent_nodes, "chain", {"sequency" : "chain1"})

#5. 修改节点文本

#定位节点

text_nodes = get_node_by_keyvalue(find_nodes(tree, "processers/services/service/chain"), {"sequency":"chain3"})

change_node_text(text_nodes, "new text")

#6. 输出到结果文件

write_xml(tree, "./out.xml")

通过main处理后的结果文件：

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<?xml version='1.0' encoding='utf-8'?>

<framework>

<processers>

<processer file="lib64/A.so" name="AProcesser" path="/tmp">

</processer>

<processer age="1" file="lib64/B.so" name="BProcesser">

<person age="15" money="200000">this is the firest content</person>

</processer>

<processer age="1" file="lib64/B.so2222222" name="BProcesser">

<person age="15" money="200000">this is the firest content</person>

</processer>

<services>

<service name="search" output_formatter="OutPutFormatter:service_inc"

prefix="/bin/search?">

<chain sequency="chain2" />

</service>

<service name="update" prefix="/bin/update?">

<chain sequency="chain3" value="fordelete">new text</chain>

</service>

</services>

</processers>

</framework>

The end!

wklken

2012-05-25