我使用的是ElementTree Python中生成一个XML文件，但转换为纯文本时tostring功能不包括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。
是否有在ElementTree渲染XML声明适当的方法？
我很惊讶地发现，似乎没有要与ElementTree.tostring()的方式。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。即使是这样，我不认为你可以得到你的“独立”属性，而无需编写自己前面加上。
我会用LXML（见http://lxml.de/api.html）。
那么你也能：
from lxml import etree
document = etree.Element('outer')
node = etree.SubElement(document, 'inner')
print(etree.tostring(document, xml_declaration=True))
If you include the encoding='utf8', you will get an XML header：
xml.etree.ElementTree.tostring写入XML编码声明用编码=“UTF8”
示例Python代码（与Python 2和3的工作原理）：
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'))
Python 2中的输出：
$ python2 example.py
without:
<xml><test>123</test></xml>
with:
<?xml version='1.0' encoding='utf8'?>
<xml><test>123</test></xml>
使用Python 3，你会注意到the b prefix指示返回（就像使用Python 2）字节的文字：
$ python3 example.py
without:
b'<xml><test>123</test></xml>'
with:
b"<?xml version='1.0' encoding='utf8'?>\n<xml><test>123</test></xml>"
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是功能ElementTree.write的定义
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, {})
因此，答案是，如果需要XML头写信给你的文件，设置比encoding或utf-8，如其他us-ascii说法UTF-8
最小工作示例与ElementTree包用法：
import xml.etree.ElementTree as ET
document = ET.Element('outer')
node = ET.SubElement(document, 'inner')
node.text = '1'
res = ET.tostring(document, encoding='utf8', method='xml').decode()
print(res)
输出是：
<?xml version='1.0' encoding='utf8'?>
<outer><inner>1</inner></outer>
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))
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=" ")
我没有发现的文档中添加standalone论点的替代，所以我适应了ET.tosting功能，把它作为一个参数。
from xml.etree import ElementTree as ET
# Sample
document = ET.Element('outer')
node = ET.SubElement(document, 'inner')
et = ET.ElementTree(document)
# Function that you need
def tostring(element, declaration, encoding=None, method=None,):
class dummy:
pass
data = []
data.append(declaration+"\n")
file = dummy()
file.write = data.append
ET.ElementTree(element).write(file, encoding, method=method)
return "".join(data)
# Working example
xdec = """<?xml version="1.0" encoding="UTF-8" standalone="no" ?>"""
xml = tostring(document, encoding='utf-8', declaration=xdec)
另一个非常简单的选择是所需的标题并置到这样的XML字符串：
xml = (bytes('<?xml version="1.0" encoding="UTF-8"?>\n', encoding='utf-8') + ET.tostring(root))
xml = xml.decode('utf-8')
with open('invoice.xml', 'w+') as f:
f.write(xml)