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

使用xml文档

<?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>

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

实现代码

#!/usr/bin/python# -*- coding=utf-8 -*-# author : wklken@yeah.net# date: 2012-05-25# version: 0.1from xml.etree.ElementTree import ElementTree,Elementdef 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 treedef 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 = textdef 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 elementdef 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")

修改后的结果

<?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>