python中lxml的应用

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()