从Python输出XML的最简单的非内存密集型方法是什么?
时间:2020-03-06 14:22:00 来源:igfitidea点击:
基本上,它类似于System.Xml.XmlWriter的一种流XML Writer,不会产生太多的内存开销。这样就排除了xml.dom和xml.dom.minidom。有什么建议吗?
解决方案
我想我有你的毒药:
http://sourceforge.net/projects/xmlite
干杯
xml.etree.cElementTree,自2.5开始包含在CPython的默认发行版中。快速读写XML。
我对lxml总是有好的结果。安装起来很麻烦,因为它主要是围绕libxml2的包装器,但是lxml.etree`树对象有一个.write()方法,该方法需要将类似文件的对象流式传输到。
from lxml.etree import XML tree = XML('<root><a><b/></a></root>') tree.write(your_file_object)
几年前,我使用了4suite的MarkupWriter
General-purpose utility class for generating XML (may eventually be expanded to produce more output types) Sample usage: from Ft.Xml import MarkupWriter writer = MarkupWriter(indent=u"yes") writer.startDocument() writer.startElement(u'xsa') writer.startElement(u'vendor') #Element with simple text (#PCDATA) content writer.simpleElement(u'name', content=u'Centigrade systems') #Note writer.text(content) still works writer.simpleElement(u'email', content=u"[email protected]") writer.endElement(u'vendor') #Element with an attribute writer.startElement(u'product', attributes={u'id': u"100\u00B0"}) #Note writer.attribute(name, value, namespace=None) still works writer.simpleElement(u'name', content=u"100\u00B0 Server") #XML fragment writer.xmlFragment('<version>1.0</version><last-release>20030401</last-release>') #Empty element writer.simpleElement(u'changes') writer.endElement(u'product') writer.endElement(u'xsa') writer.endDocument() Note on the difference between 4Suite writers and printers Writer - module that exposes a broad public API for building output bit by bit Printer - module that simply takes a DOM and creates output from it as a whole, within one API invokation
最近,我听到很多有关lxml的优点的信息,但是我没有第一手的经验,并且在使用gnosis的过程中获得了一些乐趣。
我想我们会发现xml.sax.saxutils中的XMLGenerator是我们想要的最接近的东西。
import time from xml.sax.saxutils import XMLGenerator from xml.sax.xmlreader import AttributesNSImpl LOG_LEVELS = ['DEBUG', 'WARNING', 'ERROR'] class xml_logger: def __init__(self, output, encoding): """ Set up a logger object, which takes SAX events and outputs an XML log file """ logger = XMLGenerator(output, encoding) logger.startDocument() attrs = AttributesNSImpl({}, {}) logger.startElementNS((None, u'log'), u'log', attrs) self._logger = logger self._output = output self._encoding = encoding return def write_entry(self, level, msg): """ Write a log entry to the logger level - the level of the entry msg - the text of the entry. Must be a Unicode object """ #Note: in a real application, I would use ISO 8601 for the date #asctime used here for simplicity now = time.asctime(time.localtime()) attr_vals = { (None, u'date'): now, (None, u'level'): LOG_LEVELS[level], } attr_qnames = { (None, u'date'): u'date', (None, u'level'): u'level', } attrs = AttributesNSImpl(attr_vals, attr_qnames) self._logger.startElementNS((None, u'entry'), u'entry', attrs) self._logger.characters(msg) self._logger.endElementNS((None, u'entry'), u'entry') return def close(self): """ Clean up the logger object """ self._logger.endElementNS((None, u'log'), u'log') self._logger.endDocument() return if __name__ == "__main__": #Test it out import sys xl = xml_logger(sys.stdout, 'utf-8') xl.write_entry(2, u"Vanilla log entry") xl.close()
我们可能想看一下我从http://www.xml.com/pub/a/2003/03/12/py-xml.html获得的文章的其余部分。
对ElementTree进行第二次表决(cElementTree是一种C实现,速度更快,例如cPickle与pickle)。这里有一些简短的示例代码,我们可以查看一下它们的工作原理:http://effbot.org/zone/element-index.htm
(这是Fredrik Lundh,他是第一个编写模块的人。太好了,它已经用2.5编写到标准库中:-)