用ElementT在python中解析xml

3条回答

网友

1楼 · 编辑于 2024-05-16 18:06:57

如果您不关心（可能是混乱的）XML文档的特定结构，只想快速获取给定标记/元素的内容，那么您可能需要尝试BeautifulSoup模块。

import BeautifulSoup
from BeautifulSoup import BeautifulSoup

soup = BeautifulSoup(totstring)

body = soup.find("body")

bodytext = body.text

网友

2楼 · 编辑于 2024-05-16 18:06:57

我不知道这是否还能帮上忙，但我遇到了一个类似的问题，需要将我的xml数据放到元素树中，而不是美化组或lxml的soupparser。我也不想在xml文件中进行两次传递。所以，我找到了如何为ElementTree（而不是ElementTree）构建自定义的XMLParser。使用Mike的一些代码，我创建了一个XMLParser类，它可以截取字符数据并在经过解析器之前过滤掉无效字符。

给你：

import xml.etree.ElementTree as ET
import sys
import re

class MyXMLParser(ET.XMLParser):

    rx = re.compile("&#([0-9]+);|&#x([0-9a-fA-F]+);")

    def feed(self,data):
        m = self.rx.search(data)
        if m is not None:
            target = m.group(1)
            if target:
                num = int(target)
            else:
                num = int(m.group(2), 16)
            if not(num in (0x9, 0xA, 0xD) or 0x20 <= num <= 0xD7FF
                   or 0xE000 <= num <= 0xFFFD or 0x10000 <= num <= 0x10FFFF):
                # is invalid xml character, cut it out of the stream
                print 'removing %s' % m.group()
                mstart, mend = m.span()
                mydata = data[:mstart] + data[mend:]
        else:
            mydata = data
        super(MyXMLParser,self).feed(mydata)


parser = MyXMLParser(encoding='utf-8')
xml_filename = sys.argv[1]
xml_etree = ET.parse(xml_filename, parser=parser)

网友

3楼 · 编辑于 2024-05-16 18:06:57

你的第一个线索可能是当你收到这样的信息。。。

>>> from xml.etree import ElementTree
>>> parse = ElementTree.parse('foo.xml')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.6/xml/etree/ElementTree.py", line 862, in parse
    tree.parse(source, parser)
  File "/usr/lib/python2.6/xml/etree/ElementTree.py", line 586, in parse
    parser.feed(data)
  File "/usr/lib/python2.6/xml/etree/ElementTree.py", line 1245, in feed
    self._parser.Parse(data, 0)
xml.parsers.expat.ExpatError: reference to invalid character number: line 11, column 0
>>>

此错误来自XML源中的无效字符。您需要清除无效字符（请参阅我的答案底部的fix_xml.py）。

有了干净的XML之后，就很容易了。应该使用StringIO将字符串视为文件：

>>> from xml.etree import ElementTree
>>> from StringIO import StringIO
>>> text = open('foo.xml', 'r').read()
>>> tree = ElementTree.parse(StringIO(text))
>>> tree.find('//BODY')
<Element BODY at b723cf2c>
>>> tree.find('//BODY').text
'Showers continued throughout the week in\nthe Bahia cocoa zone, alleviating the drought since early\nJanuary and improving prospects for the coming temporao,\nalthough normal humidity levels have not been restored,\nComissaria Smith said in its weekly review.\n    The dry period means the temporao will be late this year.\n    Arrivals for the week ended February 22 were 155,221 bags\nof 60 kilos making a cumulative total for the season of 5.93\nmln against 5.81 at the same stage last year. Again it seems\nthat cocoa delivered earlier on consignment was included in the\narrivals figures.\n    Comissaria Smith said there is still some doubt as to how\nmuch old crop cocoa is still available as harvesting has\npractically come to an end. With total Bahia crop estimates\naround 6.4 mln bags and sales standing at almost 6.2 mln there\nare a few hundred thousand bags still in the hands of farmers,\nmiddlemen, exporters and processors.\n    There are doubts as to how much of this cocoa would be fit\nfor export as shippers are now experiencing dificulties in\nobtaining +Bahia superior+ certificates.\n    In view of the lower quality over recent weeks farmers have\nsold a good part of their cocoa held on consignment.\n    Comissaria Smith said spot bean prices rose to 340 to 350\ncruzados per arroba of 15 kilos.\n    Bean shippers were reluctant to offer nearby shipment and\nonly limited sales were booked for March shipment at 1,750 to\n1,780 dlrs per tonne to ports to be named.\n    New crop sales were also light and all to open ports with\nJune/July going at 1,850 and 1,880 dlrs and at 35 and 45 dlrs\nunder New York july, Aug/Sept at 1,870, 1,875 and 1,880 dlrs\nper tonne FOB.\n    Routine sales of butter were made. March/April sold at\n4,340, 4,345 and 4,350 dlrs.\n    April/May butter went at 2.27 times New York May, June/July\nat 4,400 and 4,415 dlrs, Aug/Sept at 4,351 to 4,450 dlrs and at\n2.27 and 2.28 times New York Sept and Oct/Dec at 4,480 dlrs and\n2.27 times New York Dec, Comissaria Smith said.\n    Destinations were the U.S., Covertible currency areas,\nUruguay and open ports.\n    Cake sales were registered at 785 to 995 dlrs for\nMarch/April, 785 dlrs for May, 753 dlrs for Aug and 0.39 times\nNew York Dec for Oct/Dec.\n    Buyers were the U.S., Argentina, Uruguay and convertible\ncurrency areas.\n    Liquor sales were limited with March/April selling at 2,325\nand 2,380 dlrs, June/July at 2,375 dlrs and at 1.25 times New\nYork July, Aug/Sept at 2,400 dlrs and at 1.25 times New York\nSept and Oct/Dec at 1.25 times New York Dec, Comissaria Smith\nsaid.\n    Total Bahia sales are currently estimated at 6.13 mln bags\nagainst the 1986/87 crop and 1.06 mln bags against the 1987/88\ncrop.\n    Final figures for the period to February 28 are expected to\nbe published by the Brazilian Cocoa Trade Commission after\ncarnival which ends midday on February 27.\n Reuter\n'
>>>

我从XML源中删除了以下字符来清理它。。。

(py26_default)[mpenning@Bucksnort ~]$ python fix_xml.py foo.xml
bar.xml
343 &#5;
347 &#5;
351 &#5;
359 &#22;
364 &#22;
369 &#1;
378 &#31;
444 &#2;
3393 &#3;
(py26_default)[mpenning@Bucksnort ~]$

记住还有其他的方法。。。^{}还会清除错误的XML。示例lxml.soupparser用法

from lxml.html import soupparser
from StringIO import StringIO
try:
    parser = XMLParser(ns_clean=True, recover=True)
    tree = ET.parse(StringIO(text), parser)
except UnicodeDecodeError:
    tree = soupparser.parse(StringIO(text))

清除xml

<!DOCTYPE lewis SYSTEM "lewis.dtd">
<REUTERS TOPICS="YES" LEWISSPLIT="TRAIN" CGISPLIT="TRAINING-SET" OLDID="5544" NEWID="1">
<DATE>26-FEB-1987 15:01:01.79</DATE>
<TOPICS><D>cocoa</D></TOPICS>
<PLACES><D>el-salvador</D><D>usa</D><D>uruguay</D></PLACES>
<PEOPLE></PEOPLE>
<ORGS></ORGS>
<EXCHANGES></EXCHANGES>
<COMPANIES></COMPANIES>
<UNKNOWN>
C T
f0704reute
u f BC-BAHIA-COCOA-REVIEW   02-26 0105</UNKNOWN>
<TEXT>
<TITLE>BAHIA COCOA REVIEW</TITLE>
<DATELINE>    SALVADOR, Feb 26 - </DATELINE><BODY>Showers continued throughout the week in
the Bahia cocoa zone, alleviating the drought since early
January and improving prospects for the coming temporao,
although normal humidity levels have not been restored,
Comissaria Smith said in its weekly review.
    The dry period means the temporao will be late this year.
    Arrivals for the week ended February 22 were 155,221 bags
of 60 kilos making a cumulative total for the season of 5.93
mln against 5.81 at the same stage last year. Again it seems
that cocoa delivered earlier on consignment was included in the
arrivals figures.
    Comissaria Smith said there is still some doubt as to how
much old crop cocoa is still available as harvesting has
practically come to an end. With total Bahia crop estimates
around 6.4 mln bags and sales standing at almost 6.2 mln there
are a few hundred thousand bags still in the hands of farmers,
middlemen, exporters and processors.
    There are doubts as to how much of this cocoa would be fit
for export as shippers are now experiencing dificulties in
obtaining +Bahia superior+ certificates.
    In view of the lower quality over recent weeks farmers have
sold a good part of their cocoa held on consignment.
    Comissaria Smith said spot bean prices rose to 340 to 350
cruzados per arroba of 15 kilos.
    Bean shippers were reluctant to offer nearby shipment and
only limited sales were booked for March shipment at 1,750 to
1,780 dlrs per tonne to ports to be named.
    New crop sales were also light and all to open ports with
June/July going at 1,850 and 1,880 dlrs and at 35 and 45 dlrs
under New York july, Aug/Sept at 1,870, 1,875 and 1,880 dlrs
per tonne FOB.
    Routine sales of butter were made. March/April sold at
4,340, 4,345 and 4,350 dlrs.
    April/May butter went at 2.27 times New York May, June/July
at 4,400 and 4,415 dlrs, Aug/Sept at 4,351 to 4,450 dlrs and at
2.27 and 2.28 times New York Sept and Oct/Dec at 4,480 dlrs and
2.27 times New York Dec, Comissaria Smith said.
    Destinations were the U.S., Covertible currency areas,
Uruguay and open ports.
    Cake sales were registered at 785 to 995 dlrs for
March/April, 785 dlrs for May, 753 dlrs for Aug and 0.39 times
New York Dec for Oct/Dec.
    Buyers were the U.S., Argentina, Uruguay and convertible
currency areas.
    Liquor sales were limited with March/April selling at 2,325
and 2,380 dlrs, June/July at 2,375 dlrs and at 1.25 times New
York July, Aug/Sept at 2,400 dlrs and at 1.25 times New York
Sept and Oct/Dec at 1.25 times New York Dec, Comissaria Smith
said.
    Total Bahia sales are currently estimated at 6.13 mln bags
against the 1986/87 crop and 1.06 mln bags against the 1987/88
crop.
    Final figures for the period to February 28 are expected to
be published by the Brazilian Cocoa Trade Commission after
carnival which ends midday on February 27.
 Reuter
</BODY></TEXT>
</REUTERS>

John Machin的错误XML finder（fix_XML.py）

正如John Machin提到的in this answer，有些字符不是有效的XML；这是他编写的帮助查找无效XML字符的脚本。

# coding: ascii
# Find numeric character references that refer to Unicode code points
# that are not valid in XML.
# Get byte offsets for seeking etc in undecoded file bytestreams.
# Get unicode offsets for checking against ElementTree error message,
# **IF** your input file is small enough. 

BYTE_OFFSETS = True
import sys, re, codecs
fname = sys.argv[1]
print fname
if BYTE_OFFSETS:
    text = open(fname, "rb").read()
else:
    # Assumes file is encoded in UTF-8.
    text = codecs.open(fname, "rb", "utf8").read()
rx = re.compile("&#([0-9]+);|&#x([0-9a-fA-F]+);")
endpos = len(text)
pos = 0
while pos < endpos:
    m = rx.search(text, pos)
    if not m: break
    mstart, mend = m.span()
    target = m.group(1)
    if target:
        num = int(target)
    else:
        num = int(m.group(2), 16)
    # #x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]
    if not(num in (0x9, 0xA, 0xD) or 0x20 <= num <= 0xD7FF
    or 0xE000 <= num <= 0xFFFD or 0x10000 <= num <= 0x10FFFF):
        print mstart, m.group()
    pos = mend

清除xml

John Machin的错误XML finder（fix_XML.py）

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