什麼是從Python輸出XML最簡單的非內存密集型方法？

Question

基本上，類似於System.Xml.XmlWriter的東西 - 一種流式XML編寫器，不會產生太多的內存開銷。這樣就排除了xml.dom和xml.dom.minidom。建議？

Answer 1

xml.etree.cElementTree，包含在2.5以來的CPython的默認分配。閱讀和編寫XML都閃電般快速。

Answer 2

我想我有你的毒藥：

http://sourceforge.net/projects/xmlite

乾杯

Answer 3

我一直有良好的結果lxml。這是一個痛苦的安裝，因爲它主要是圍繞libxml2包裝，但lxml.etree樹對象有一個.write()方法，需要一個類文件對象流。

from lxml.etree import XML 

tree = XML('<root><a><b/></a></root>') 
tree.write(your_file_object) 

Answer 4

幾年前，我用MarkupWriter從4suite

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"info@centigrade.bogus") 
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 

最近我聽到了很多關於如何lxml是偉大的，但我沒有第一手的經驗，和我與gnosis工作有一些樂趣。

Answer 5

我想你會從xml.sax.saxutils找到XMLGenerator是最接近你想要的東西。

 
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() 

你可能會想看看本文的其餘部分我是從http://www.xml.com/pub/a/2003/03/12/py-xml.html。

Answer 6

ElementTree的第二票（cElementTree是一個C實現，有點快，就像cPickle vs pickle）。這裏有一些簡短的示例代碼，你可以看看它們，讓你知道它是如何工作的：http://effbot.org/zone/element-index.htm （這是Fredrik Lundh，他首先編寫了這個模塊，它非常好用2.5編寫的標準庫:-)）