忠实地保留解析的XML中的注释

Question

我想在处理XML时尽可能忠实地保留注释。

我设法保留了注释，但是内容已被XML转义。

#!/usr/bin/env python
# add_host_to_tomcat.py

import xml.etree.ElementTree as ET
from CommentedTreeBuilder import CommentedTreeBuilder
parser = CommentedTreeBuilder()

if __name__ == '__main__':
    filename = "/opt/lucee/tomcat/conf/server.xml"

    # this is the important part: use the comment-preserving parser
    tree = ET.parse(filename, parser)

    # get the node to add a child to
    engine_node = tree.find("./Service/Engine")

    # add a node: Engine.Host
    host_node = ET.SubElement(
        engine_node,
        "Host",
        name="local.mysite.com",
        appBase="webapps"
    )
    # add a child to new node: Engine.Host.Context
    ET.SubElement(
        host_node,
        'Context',
        path="",
        docBase="/path/to/doc/base"
    )

    tree.write('out.xml')



#!/usr/bin/env python
# CommentedTreeBuilder.py

from xml.etree import ElementTree

class CommentedTreeBuilder ( ElementTree.XMLTreeBuilder ):
    def __init__ ( self, html = 0, target = None ):
        ElementTree.XMLTreeBuilder.__init__( self, html, target )
        self._parser.CommentHandler = self.handle_comment

    def handle_comment ( self, data ):
        self._target.start( ElementTree.Comment, {} )
        self._target.data( data )
        self._target.end( ElementTree.Comment )

但是，像这样的注释：

  <!--
EXAMPLE HOST ENTRY:
    <Host name="lucee.org" appBase="webapps">
         <Context path="" docBase="/var/sites/getrailo.org" />
     <Alias>www.lucee.org</Alias>
     <Alias>my.lucee.org</Alias>
    </Host>

HOST ENTRY TEMPLATE:
    <Host name="[ENTER DOMAIN NAME]" appBase="webapps">
         <Context path="" docBase="[ENTER SYSTEM PATH]" />
     <Alias>[ENTER DOMAIN ALIAS]</Alias>
    </Host>
  -->

最终为：

  <!--
            EXAMPLE HOST ENTRY:
    &lt;Host name="lucee.org" appBase="webapps"&gt;
         &lt;Context path="" docBase="/var/sites/getrailo.org" /&gt;
         &lt;Alias&gt;www.lucee.org&lt;/Alias&gt;
         &lt;Alias&gt;my.lucee.org&lt;/Alias&gt;
    &lt;/Host&gt;

    HOST ENTRY TEMPLATE:
    &lt;Host name="[ENTER DOMAIN NAME]" appBase="webapps"&gt;
         &lt;Context path="" docBase="[ENTER SYSTEM PATH]" /&gt;
         &lt;Alias&gt;[ENTER DOMAIN ALIAS]&lt;/Alias&gt;
    &lt;/Host&gt;
   -->

我也尝试self._target.data( saxutils.unescape(data) )过CommentedTreeBuilder.py，但似乎没有任何作用。实际上，我认为问题出在handle_commment()步骤之后的某个地方。

顺便说一句，这个问题与此类似。

Answer 1

经过Python 2.7和3.5的测试，以下代码应该可以正常工作。

#!/usr/bin/env python
# CommentedTreeBuilder.py
from xml.etree import ElementTree

class CommentedTreeBuilder(ElementTree.TreeBuilder):
    def comment(self, data):
        self.start(ElementTree.Comment, {})
        self.data(data)
        self.end(ElementTree.Comment)

然后，在主代码中使用

parser = ElementTree.XMLParser(target=CommentedTreeBuilder())

作为解析器，而不是当前的解析器。

顺便说一下，使用开箱即用的注释可以正常工作lxml。也就是说，你可以做

import lxml.etree as ET
tree = ET.parse(filename)

不需要以上任何一项。