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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]
- <?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./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:
- #!/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:
- <?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
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