python之lxml 解析问题总结

python3 env

（1）解析xml报错 ValueError: Unicode strings with encoding declaration are not supported. Please use bytes input or XML fragments without declaration.

• lxml 不支持解析带有encoding 声明的字符串，例如 xml中以encoding="UTF-8"开头，需要转换成bytes类型。案例一， 案例二

from lxml import etree

content = '''<?xml version="1.0"?>
<response version="1.0">
<code>200</code>
<message>Hello</message>
</response>'''

etree.fromstring(content)
Out[12]: <Element response at 0x7f2fad8d4c08>



content = '''<?xml version="1.0" encoding="utf-8"?>
<response version="1.0">
<code>200</code>
<message>Hello</message>
</response>'''

etree.fromstring(content)
---------------------------------------------------------------------------
ValueError: Unicode strings with encoding declaration are not supported. Please use bytes input or XML fragments without declaration.



content = b'''<?xml version="1.0" encoding="utf-8"?>
<response version="1.0">
<code>200</code>
<message>Hello</message>
</response>'''

xml = etree.fromstring(content)
print (xml)
Out[5]: <Element response at 0x7f1a1248f288

得到上述的xml的类， 需要转化为string，要加参数encoding='unicode'

etree.tostring(xml)
Out[7]: b'<response version="1.0">\n<code>200</code>\n<message>Hello</message>\n</response>'

etree.tostring(xml, encoding='unicode')
Out[8]: '<response version="1.0">\n<code>200</code>\n<message>Hello</message>\n</response>'