缺少Android上的kivy/Python上的Unicode编解码器？

Question

我有一个在kivy下运行的程序，它在Windows上运行得很好，但是在Android上打开一个文件却失败了(这两个平台上都是1.8.0)。奇怪的是，当我明确要求utf-8时，错误消息表明它试图解码ASCII；而且文件中任何地方都没有0xFF字符--我与od实用程序进行了检查。

守则：

try:
    Logger.info('Mark: opening file ' + repr(filename))
    with codecs.open(filename, 'r', encoding='utf_8') as f:
        lines = [line.rstrip(u'\r\n').lstrip(codecs.BOM) for line in f]
except UnicodeDecodeError as e:
    Logger.info('Mark: utf8 load failed: ' + str(e))
    with codecs.open(filename, 'r', encoding='cp1252') as f:
        lines = [line.rstrip(u'\r\n') for line in f]

日志文件：

[INFO              ] Mark: opening file '/mnt/sdcard/My Files/Documents/DVDs.txt'
[INFO              ] Mark: utf8 load failed: 'ascii' codec can't decode byte 0xff in position 0: ordinal not in range(128)
[INFO              ] Base: Leaving application in progress...
[WARNING           ] stderr: Traceback (most recent call last):
[WARNING           ] stderr:   File "main.py", line 295, in <module>
[WARNING           ] stderr:     app.run()
[WARNING           ] stderr:   File "/home/tito/code/python-for-android/build/python-install/lib/python2.7/site-packages/kivy/app.py", line 792, in run
[WARNING           ] stderr:   File "/home/tito/code/python-for-android/build/python-install/lib/python2.7/site-packages/kivy/base.py", line 481, in runTouchApp
[WARNING           ] stderr:   File "/home/tito/code/python-for-android/build/python-install/lib/python2.7/site-packages/kivy/core/window/window_pygame.py", line 381, in mainloop
[WARNING           ] stderr:   File "/home/tito/code/python-for-android/build/python-install/lib/python2.7/site-packages/kivy/core/window/window_pygame.py", line 287, in _mainloop
[WARNING           ] stderr:   File "/home/tito/code/python-for-android/build/python-install/lib/python2.7/site-packages/kivy/base.py", line 321, in idle
[WARNING           ] stderr:   File "/home/tito/code/python-for-android/build/python-install/lib/python2.7/site-packages/kivy/clock.py", line 422, in tick
[WARNING           ] stderr:   File "/home/tito/code/python-for-android/build/python-install/lib/python2.7/site-packages/kivy/clock.py", line 537, in _process_events
[WARNING           ] stderr:   File "/home/tito/code/python-for-android/build/python-install/lib/python2.7/site-packages/kivy/clock.py", line 309, in tick
[WARNING           ] stderr:   File "main.py", line 266, in select_file_part2
[WARNING           ] stderr:     with codecs.open(filename, 'r', encoding='cp1252') as f:
[WARNING           ] stderr:   File "/home/tito/code/python-for-android/build/python-install/lib/python2.7/codecs.py", line 884, in open
[WARNING           ] stderr: LookupError: unknown encoding: cp1252

编辑：--我输入了一些调试代码来遍历全表，发现除了ascii、latin_1和各种utf编解码器之外，所有这些代码都丢失了。

Answer 1

摆脱“尝试”/“例外”，看看真正的异常。codecs.BOM是一个字节字符串\xff\xfe，使用默认的ascii编解码器将其强制为Unicode：

>>> import codecs
>>> codecs.BOM
'\xff\xfe'
>>> u'test'.lstrip(codecs.BOM)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xff in position 0: ordinal not in range(128)