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

from : 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]

 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：

 #!/usr/bin/python
 # -*- coding=utf-8 -*-
 # author : [email protected]
 # 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 contentperson>
         processer>
         <processer age="1" file="lib64/B.so2222222" name="BProcesser">
             <person age="15" money="200000">this is the firest contentperson>
         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 textchain>
             service>
         services>
     processers>
 framework>

The end!

wklken

2012-05-25