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python中lxml的应用

2024-07-06 13:20:18   224人阅读

首先下载lxml， http://www.lfd.uci.edu/~gohlke/pythonlibs/ ，然后添加引用
fromlxml import _elementpathasDONTUSE
fromlxml import etree


具体示例：
1.添加命名空间
#set namespace
nsmap = {"xsi":"http://www.w3.org/2001/XMLSchema-instance"}
g_statisticsRoot = etree.Element("DcmStatistics", nsmap = nsmap)

2.添加xml schema引用
#add xsd reference
g_statisticsRoot.set("{http://www.w3.org/2001/XMLSchema-instance}noNamespaceSchemaLocation","DcmStatistics.xsd")

3.添加注释
#add comment， 利用addprevious添加到根节点的前面
comment = etree.Comment("create by jiangong.li")
g_statisticsRoot.addprevious(comment)

4.尝试多种编码来解析xml
defdecodingXml(xmlFile):
    tree = None
    encoding ="utf-8"

   while(True):
       try:
            parser = etree.XMLParser(remove_blank_text=True, encoding=encoding, remove_comments =False)
            tree = etree.parse(xmlFile, parser)
       exceptExceptionase:
           if(encoding !="gb18030"):
                encoding ="gb18030"
               continue
           else:
                print("\nPAR XML ERROR, decoding error.")
               break
       break
   returntree

5.遍历xml下的所有子节点，不止直属第一级子节点.iter()
     forelementinroot.iter():
          element.tail=None

6.遍历xml下的第一级子节点.iterchildren()
    fore in srcParentNode.iterchildren():
       ife is srcParentNode:
           continue

        name =""
       #statistics node
       if  e.tag =="element":
            name ="Element"
       elife.tag =="sequence":
            name ="Sequence"
       elife.tag =="item":
            name ="Item"
       else:
            print("\nUnsupported element type: %s\n"%(e.tag))
            name = e.tag
           # Only parse element/sequence/item
            continue     

7.添加子节点到尾部. append()
defgetXmlElement(nodeName, parentNode):
   ifparentNode  == None:
       raiseException("parent node is None")

    nodes = parentNode.xpath('./'+nodeName)

   iflen(nodes) == 0:
        node = etree.Element(nodeName)
        parentNode.append(node)
       returnnode
   else:
       returnnodes[0]

8.格式化成str输出
etree.tostring(g_statisticsRoot, encoding="UTF-8", xml_declaration=True, pretty_print=True, with_comments=True)

9.保存成xml文件
        statisticsResult =  open(g_xmlName,"bw+")
        statisticsResult.write(etree.tostring(g_statisticsRoot, encoding="UTF-8", xml_declaration=True, pretty_print=True, with_comments=True))
        statisticsResult.flush()
        statisticsResult.close()


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