Python xml属性/节点/文本的增删改[xml.etree.ElementTree]

http://blog.csdn.net/wklken/article/details/7603071

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

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