python于lxml应用

首先下载lxml， http://www.lfd.uci.edu/~gohlke/pythonlibs/ ，然后加入引用

from
lxml
import _elementpath
as
DONTUSE

from
lxml
import etree

详细演示样例：

1.加入命名空间

#set namespace

nsmap = {"xsi":
"http://www.w3.org/2001/XMLSchema-instance"
}

g_statisticsRoot = etree.Element("DcmStatistics",
nsmap = nsmap)

2.加入xml schema引用

#add xsd reference

g_statisticsRoot.set("{http://www.w3.org/2001/XMLSchema-instance}noNamespaceSchemaLocation",
"DcmStatistics.xsd"
)

3.加入凝视

#add comment。 利用addprevious加入到根节点的前面

comment = etree.Comment("create by jiangong.li")

g_statisticsRoot.addprevious(comment)

4.尝试多种编码来解析xml

def
decodingXml(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)

       
except
Exception
as
e:

           
if
(encoding !=
"gb18030"):

                encoding =
"gb18030"

               
continue

           
else:

                print(
"\nPAR XML ERROR, decoding error."
)

               
break

       
break

   
return
tree

5.遍历xml下的全部子节点，不止直属第一级子节点.
iter()

     for
element
in
root.iter():

          element.tail
=
None

6.遍历xml下的第一级子节点.
iterchildren()

    for
e
in srcParentNode.iterchildren():

       
if
e
is srcParentNode:

           
continue

        name =
""

       
#statistics node

       
if  e.tag ==
"element":

            name =
"Element"

       
elif
e.tag ==
"sequence":

            name =
"Sequence"

       
elif
e.tag ==
"item":

            name =
"Item"

       
else:

            print(
"\nUnsupported element type: %s\n"
%(e.tag))

            name = e.tag

           
# Only parse element/sequence/item

            
continue     

7.加入子节点到尾部.
append()

def
getXmlElement(nodeName, parentNode):

   
if
parentNode  == None:

       
raise
Exception(
"parent node is None")

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

   
if
len(nodes) == 0:

        node = etree.Element(nodeName)

        parentNode.append(node)

       
return
node

   
else:

       
return
nodes[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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