python从字符串中不能解码gbk编码？

Question

我用“gbk”编码xml：

#!/usr/bin/env python
# encoding: utf-8
from xml.etree.ElementTree import Element, SubElement, tostring, fromstring, XML, XMLParser

root = Element('root')
child = SubElement(root, "child")
child.text = u"中文"

result = tostring(root, encoding="gbk")
print(result)
print(result.decode("gbk"))

这将产生如下结果：

b"<?xml version='1.0' encoding='gbk'?>\n<root><child>\xd6\xd0\xce\xc4</child></root>"

所以，我试图像这样解析xml，我这样做：

tree = XML(result.decode("gbk"))
print(tree[0].text)
tree = XML(result.decode("gbk"), parser=XMLParser(encoding="gbk"))
print(tree[0].text)
tree = XML(result.decode("gbk"), parser=XMLParser(encoding="utf-8"))
print(tree[0].text)

我发现它们都在python 3.6中工作，但是没有一个在python 2.7中工作，python 2.7中的错误是：

UnicodeEncodeError: 'ascii' codec can't encode characters in position 50-51: ordinal not in range(128)

所以，我有两个问题：

1. 为什么两个XMLParser(encoding="gbk") XMLParser(encoding="utf-8")在python3.6中返回相同的结果
2. 如何使xml解析器在python2.7中正常工作？(我不认为result.decode('gbk').encode('utf8').replace('GBK', 'utf-8')是个好主意。)

Answer 1

>>> from xml.etree.ElementTree import Element, SubElement, tostring, XML
>>> root = Element("root")
>>> child = SubElement(root, "child")
>>> child.text = u"中文"
>>> result = tostring(root, encoding="utf-8")  # Return str in Py2, Return bytes in Py3
>>> result
'<root><child>\xe4\xb8\xad\xe6\x96\x87</child></root>'
>>> print type(result)
<type 'str'>  # The type str in Py2 is the type bytes in Py3
>>> print result.deocde("utf-8")
<root><child>中文</child></root>
>>> tree = XML(result)
>>> print tree[0].text
中文

对于第二个问题，以上代码在Python2.7中工作。

更新

我想您的目的是从gbk编码的字符串构造XML。您可以在lxml中使用Python2，也可以直接使用Python3。

>>> from lxml import etree
>>> root = etree.Element("root")
>>> child = etree.SubElement(root, "child")
>>> child.text = u"中文"
>>> result = etree.tostring(root, encoding="gbk")
>>> result
"<?xml version='1.0' encoding='gbk'?>\n<root><child>\xd6\xd0\xce\xc4</child></root>"
>>> tree = etree.XML(result)
>>> tree[0].text
u'\u4e2d\u6587'