Python 使用lxml解析期间解析外部未解析实体

在使用lxml解析期间，如何解析外部未解析的实体

下面是我的代码示例：

import io

from lxml import etree

content = b"""\
<?xml version="1.0"?>
<!DOCTYPE sample [
<!NOTATION jpeg SYSTEM "image/jpeg">
<!ENTITY ref1 SYSTEM "python-logo-small.jpg" NDATA jpeg>
<!ELEMENT sample EMPTY>
<!ATTLIST sample src ENTITY #REQUIRED>
]>
<sample src="ref1"/>
"""

parser = etree.XMLParser(dtd_validation=True, resolve_entities=True)
doc = etree.parse(io.BytesIO(content), parser=parser)
print(etree.tostring(doc))

但我有同样的结果

或者，我想自己解决这些实体。为此，我尝试以这种方式列出实体：

for entity in doc.docinfo.internalDTD.iterentities():
    msg_fmt = "{entity.name!r}, {entity.content!r}, {entity.orig!r}"
    print(msg_fmt.format(entity=entity))

但我只得到实体和符号的名称，而不是实体的定义：

'ref1', 'jpeg', None

---

如何访问实体的定义？

包含未解析实体的XML文档看起来正常。但是，未解析的实体不会以您似乎期望的方式得到解析。如果要在已解析的输出中查看

，请使用内部（已解析）实体

例如：

import io
from lxml import etree

content = b"""\
<?xml version="1.0"?>
<!DOCTYPE sample [
<!ENTITY ref1 "python-logo-small.jpg">
<!ELEMENT sample EMPTY>
<!ATTLIST sample src CDATA #REQUIRED>
]>
<sample src="&ref1;"/>
"""

parser = etree.XMLParser(dtd_validation=True, resolve_entities=True)
doc = etree.parse(io.BytesIO(content), parser=parser)
print(etree.tostring(doc))

输出：

python-logo-small.jpg

好的，不可能“解析”外部未解析实体，但我们可以列出它们：

import io

import xml.sax

content = b"""\
<?xml version="1.0"?>
<!DOCTYPE sample [
<!NOTATION jpeg SYSTEM "image/jpeg">
<!ENTITY ref1 SYSTEM "python-logo-small.jpg" NDATA jpeg>
<!ELEMENT sample EMPTY>
<!ATTLIST sample src ENTITY #REQUIRED>
]>
<sample src="ref1"/>
"""


class MyDTDHandler(xml.sax.handler.DTDHandler):
    def __init__(self):
        pass

    def unparsedEntityDecl(self, name, publicId, systemId, ndata):
        print(dict(name=name, publicId=publicId, systemId=systemId, ndata=ndata))
        xml.sax.handler.DTDHandler.unparsedEntityDecl(self, name, publicId, systemId, ndata)


parser = xml.sax.make_parser()
parser.setDTDHandler(MyDTDHandler())
parser.parse(io.BytesIO(content))

---

工作已经完成。

不幸的是，我不是XML内容的作者，因此无法修改它。有没有办法列出内部实体？有关于xml.sax.handler的例子吗？

xsl = etree.XML('''\
<xsl:stylesheet version="1.0" 
     xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output encoding="utf-8" omit-xml-declaration="yes"/>
 <xsl:template match="sample">
   <xsl:value-of select="unparsed-entity-uri(@src)"/>
 </xsl:template>
</xsl:stylesheet>
''')

transform = etree.XSLT(xsl)
result = transform(doc)
print result

python-logo-small.jpg

import io

import xml.sax

content = b"""\
<?xml version="1.0"?>
<!DOCTYPE sample [
<!NOTATION jpeg SYSTEM "image/jpeg">
<!ENTITY ref1 SYSTEM "python-logo-small.jpg" NDATA jpeg>
<!ELEMENT sample EMPTY>
<!ATTLIST sample src ENTITY #REQUIRED>
]>
<sample src="ref1"/>
"""


class MyDTDHandler(xml.sax.handler.DTDHandler):
    def __init__(self):
        pass

    def unparsedEntityDecl(self, name, publicId, systemId, ndata):
        print(dict(name=name, publicId=publicId, systemId=systemId, ndata=ndata))
        xml.sax.handler.DTDHandler.unparsedEntityDecl(self, name, publicId, systemId, ndata)


parser = xml.sax.make_parser()
parser.setDTDHandler(MyDTDHandler())
parser.parse(io.BytesIO(content))

{'systemId': u'python-logo-small.jpg', 'ndata': u'jpeg', 'publicId': None, 'name': u'ref1'}