如何使用xml.etree.ElementTree编写XML声明

Question

我使用ElementTree在Python中生成XML文档，但tostring函数在转换为纯文本时不包含XML declaration。

from xml.etree.ElementTree import Element, tostring 

document = Element('outer') 
node = SubElement(document, 'inner') 
node.NewValue = 1 
print tostring(document) # Outputs "<outer><inner /></outer>" 

我需要我的字符串包括以下XML声明：

<?xml version="1.0" encoding="UTF-8" standalone="yes" ?> 

然而，似乎没有被这样做的任何记录的方式。

是否有合适的方法来呈现ElementTree中的XML声明？

Answer 1

我很惊讶地发现，似乎没有要与ElementTree.tostring()一种方式。但是，您可以使用ElementTree.ElementTree.write()到XML文档写入文件假货：

from io import BytesIO 
from xml.etree import ElementTree as ET 

document = ET.Element('outer') 
node = ET.SubElement(document, 'inner') 
et = ET.ElementTree(document) 

f = BytesIO() 
et.write(f, encoding='utf-8', xml_declaration=True) 
print(f.getvalue()) # your XML file, encoded as UTF-8 

见this question。即使那样，我也不认为你可以在没有自己预先写好的情况下得到你的“独立”属性。

Answer 2

我会使用lxml（请参阅http://lxml.de/api.html）。

然后，您可以：

from lxml import etree 
document = etree.Element('outer') 
node = etree.SubElement(document, 'inner') 
print(etree.tostring(document, xml_declaration=True)) 

Answer 3

我最近遇到此问题，代码的一些挖后，我发现下面的代码片段的功能ElementTree.write

def write(self, file, encoding="us-ascii"): 
    assert self._root is not None 
    if not hasattr(file, "write"): 
     file = open(file, "wb") 
    if not encoding: 
     encoding = "us-ascii" 
    elif encoding != "utf-8" and encoding != "us-ascii": 
     file.write("<?xml version='1.0' encoding='%s'?>\n" % 
    encoding) 
    self._write(file, self._root, encoding, {}) 

定义因此，答案是，如果需要XML头写入到文件，设置除utf-8或us-ascii之外的其他参数encoding，例如UTF-8

Answer 4

我会用ET：

try: 
    from lxml import etree 
    print("running with lxml.etree") 
except ImportError: 
    try: 
     # Python 2.5 
     import xml.etree.cElementTree as etree 
     print("running with cElementTree on Python 2.5+") 
    except ImportError: 
     try: 
      # Python 2.5 
      import xml.etree.ElementTree as etree 
      print("running with ElementTree on Python 2.5+") 
     except ImportError: 
      try: 
       # normal cElementTree install 
       import cElementTree as etree 
       print("running with cElementTree") 
      except ImportError: 
       try: 
        # normal ElementTree install 
        import elementtree.ElementTree as etree 
        print("running with ElementTree") 
       except ImportError: 
        print("Failed to import ElementTree from any known place") 

document = etree.Element('outer') 
node = etree.SubElement(document, 'inner') 
print(etree.tostring(document, encoding='UTF-8', xml_declaration=True)) 

Answer 5

这工作，如果你只想打印。得到一个错误，当我尝试把它发送到一个文件...

import xml.dom.minidom as minidom 
import xml.etree.ElementTree as ET 
from xml.etree.ElementTree import Element, SubElement, Comment, tostring 

def prettify(elem): 
    rough_string = ET.tostring(elem, 'utf-8') 
    reparsed = minidom.parseString(rough_string) 
    return reparsed.toprettyxml(indent=" ") 

Answer 6

If you include the encoding='utf8', you will get an XML header：

xml.etree.ElementTree.tostring写了一个XML编码声明与编码= 'utf-8'

样品的Python 2代码：

import xml.etree.ElementTree as ElementTree 

tree = ElementTree.ElementTree(
    ElementTree.fromstring('<xml><test>123</test></xml>') 
) 
root = tree.getroot() 

print 'without:' 
print ElementTree.tostring(root, method='xml') 
print 
print 'with:' 
print ElementTree.tostring(root, encoding='utf8', method='xml') 

输出：

without: 
<xml><test>123</test></xml> 

with: 
<?xml version='1.0' encoding='utf8'?> 
<xml><test>123</test></xml>