Python之——UnicodeDecodeError: 'ascii' codec can't decode byte 0xe9 in position 0 解决办法

转载出处：http://blog.csdn.net/l1028386804/article/details/78976807

最近在用Python处理一些中文数据时，报出了如下错误：

 UnicodeDecodeError: 'ascii' codec can't decode byte 0xe9 in position 0: ordinal not in range(128)

1、原因

因为默认情况下，Python采用的是ascii编码方式，如下所示：

 python -c "import sys; print sys.getdefaultencoding()"
 ascii

而Python在进行编码方式之间的转换时，会将 unicode 作为“中间编码”，但 unicode 最大只有 128 那么长，所以这里当尝试将 ascii 编码字符串转换成"中间编码" unicode 时由于超出了其范围，就报出了如上错误。

2、解决办法

1）第一种：这里我们将Python的默认编码方式修改为utf-8，就可以规避上述问题的发生，具体方式，我们在Python文件的前面加上如下代码：

 import sys
 defaultencoding = 'utf-8'
 if sys.getdefaultencoding() != defaultencoding:
     reload(sys)
     sys.setdefaultencoding(defaultencoding)

 2）第二种：我们在Python安装目录下的site-packages目录下添加一个sitecustomize.py文件，内容如下：

 import sys
 sys.setdefaultencoding('utf-8')

 这种方式可以解决所有项目的encoding问题，具体说明可参考Python安装目录下的site.py文件：

 """Append module search paths for third-party packages to sys.path.

 ****************************************************************
 * This module is automatically imported during initialization. *
 ****************************************************************

 In earlier versions of Python (up to 1.5a3), scripts or modules that
 needed to use site-specific modules would place ``import site''
 somewhere near the top of their code.  Because of the automatic
 import, this is no longer necessary (but code that does it still
 works).

 This will append site-specific paths to the module search path.  On
 Unix (including Mac OSX), it starts with sys.prefix and
 sys.exec_prefix (if different) and appends
 lib/python/site-packages as well as lib/site-python.
 On other platforms (such as Windows), it tries each of the
 prefixes directly, as well as with lib/site-packages appended.  The
 resulting directories, if they exist, are appended to sys.path, and
 also inspected for path configuration files.

 For Debian and derivatives, this sys.path is augmented with directories
 for packages distributed within the distribution. Local addons go
 into /usr/local/lib/python/dist-packages, Debian addons
 install into /usr/{lib,share}/python/dist-packages.
 /usr/lib/python/site-packages is not used.

 A path configuration file is a file whose name has the form
 .pth; its contents are additional directories (one per line)
 to be added to sys.path.  Non-existing directories (or
 non-directories) are never added to sys.path; no directory is added to
 sys.path more than once.  Blank lines and lines beginning with
 '#' are skipped. Lines starting with 'import' are executed.

 For example, suppose sys.prefix and sys.exec_prefix are set to
 /usr/local and there is a directory /usr/local/lib/python2.5/site-packages
 with three subdirectories, foo, bar and spam, and two path
 configuration files, foo.pth and bar.pth.  Assume foo.pth contains the
 following:

   # foo package configuration
   foo
   bar
   bletch

 and bar.pth contains:

   # bar package configuration
   bar

 Then the following directories are added to sys.path, in this order:

   /usr/local/lib/python2.5/site-packages/bar
   /usr/local/lib/python2.5/site-packages/foo

 Note that bletch is omitted because it doesn't exist; bar precedes foo
 because bar.pth comes alphabetically before foo.pth; and spam is
 omitted because it is not mentioned in either path configuration file.

 After these path manipulations, an attempt is made to import a module
 named sitecustomize, which can perform arbitrary additional
 site-specific customizations.  If this import fails with an
 ImportError exception, it is silently ignored.

 """

 import sys
 import os
 import __builtin__
 import traceback

 # Prefixes for site-packages; add additional prefixes like /usr/local here
 PREFIXES = [sys.prefix, sys.exec_prefix]
 # Enable per user site-packages directory
 # set it to False to disable the feature or True to force the feature
 ENABLE_USER_SITE = None

 # for distutils.commands.install
 # These values are initialized by the getuserbase() and getusersitepackages()
 # functions, through the main() function when Python starts.
 USER_SITE = None
 USER_BASE = None


 def makepath(*paths):
     dir = os.path.join(*paths)
     try:
         dir = os.path.abspath(dir)
     except OSError:
         pass
     return dir, os.path.normcase(dir)


 def abs__file__():
     """Set all module' __file__ attribute to an absolute path"""
     for m in sys.modules.values():
         if hasattr(m, '__loader__'):
             continue   # don't mess with a PEP 302-supplied __file__
         try:
             m.__file__ = os.path.abspath(m.__file__)
         except (AttributeError, OSError):
             pass


 def removeduppaths():
     """ Remove duplicate entries from sys.path along with making them
     absolute"""
     # This ensures that the initial path provided by the interpreter contains
     # only absolute pathnames, even if we're running from the build directory.
     L = []
     known_paths = set()
     for dir in sys.path:
         # Filter out duplicate paths (on case-insensitive file systems also
         # if they only differ in case); turn relative paths into absolute
         # paths.
         dir, dircase = makepath(dir)
         if not dircase in known_paths:
             L.append(dir)
             known_paths.add(dircase)
     sys.path[:] = L
     return known_paths


 def _init_pathinfo():
     """Return a set containing all existing directory entries from sys.path"""
     d = set()
     for dir in sys.path:
         try:
             if os.path.isdir(dir):
                 dir, dircase = makepath(dir)
                 d.add(dircase)
         except TypeError:
             continue
     return d


 def addpackage(sitedir, name, known_paths):
     """Process a .pth file within the site-packages directory:
        For each line in the file, either combine it with sitedir to a path
        and add that to known_paths, or execute it if it starts with 'import '.
     """
     if known_paths is None:
         _init_pathinfo()
         reset = 1
     else:
         reset = 0
     fullname = os.path.join(sitedir, name)
     try:
         f = open(fullname, "rU")
     except IOError:
         return
     with f:
         for n, line in enumerate(f):
             if line.startswith("#"):
                 continue
             try:
                 if line.startswith(("import ", "import\t")):
                     exec line
                     continue
                 line = line.rstrip()
                 dir, dircase = makepath(sitedir, line)
                 if not dircase in known_paths and os.path.exists(dir):
                     sys.path.append(dir)
                     known_paths.add(dircase)
             except Exception as err:
                 print >>sys.stderr, "Error processing line {:d} of {}:\n".format(
                     n+1, fullname)
                 for record in traceback.format_exception(*sys.exc_info()):
                     for line in record.splitlines():
                         print >>sys.stderr, '  '+line
                 print >>sys.stderr, "\nRemainder of file ignored"
                 break
     if reset:
         known_paths = None
     return known_paths


 def addsitedir(sitedir, known_paths=None):
     """Add 'sitedir' argument to sys.path if missing and handle .pth files in
     'sitedir'"""
     if known_paths is None:
         known_paths = _init_pathinfo()
         reset = 1
     else:
         reset = 0
     sitedir, sitedircase = makepath(sitedir)
     if not sitedircase in known_paths:
         sys.path.append(sitedir)        # Add path component
     try:
         names = os.listdir(sitedir)
     except os.error:
         return
     dotpth = os.extsep + "pth"
     names = [name for name in names if name.endswith(dotpth)]
     for name in sorted(names):
         addpackage(sitedir, name, known_paths)
     if reset:
         known_paths = None
     return known_paths


 def check_enableusersite():
     """Check if user site directory is safe for inclusion

     The function tests for the command line flag (including environment var),
     process uid/gid equal to effective uid/gid.

     None: Disabled for security reasons
     False: Disabled by user (command line option)
     True: Safe and enabled
     """
     if sys.flags.no_user_site:
         return False

     if hasattr(os, "getuid") and hasattr(os, "geteuid"):
         # check process uid == effective uid
         if os.geteuid() != os.getuid():
             return None
     if hasattr(os, "getgid") and hasattr(os, "getegid"):
         # check process gid == effective gid
         if os.getegid() != os.getgid():
             return None

     return True

 def getuserbase():
     """Returns the `user base` directory path.

     The `user base` directory can be used to store data. If the global
     variable ``USER_BASE`` is not initialized yet, this function will also set
     it.
     """
     global USER_BASE
     if USER_BASE is not None:
         return USER_BASE
     from sysconfig import get_config_var
     USER_BASE = get_config_var('userbase')
     return USER_BASE

 def getusersitepackages():
     """Returns the user-specific site-packages directory path.

     If the global variable ``USER_SITE`` is not initialized yet, this
     function will also set it.
     """
     global USER_SITE
     user_base = getuserbase() # this will also set USER_BASE

     if USER_SITE is not None:
         return USER_SITE

     from sysconfig import get_path
     import os

     if sys.platform == 'darwin':
         from sysconfig import get_config_var
         if get_config_var('PYTHONFRAMEWORK'):
             USER_SITE = get_path('purelib', 'osx_framework_user')
             return USER_SITE

     USER_SITE = get_path('purelib', '%s_user' % os.name)
     return USER_SITE

 def addusersitepackages(known_paths):
     """Add a per user site-package to sys.path

     Each user has its own python directory with site-packages in the
     home directory.
     """
     # get the per user site-package path
     # this call will also make sure USER_BASE and USER_SITE are set
     user_site = getusersitepackages()

     if ENABLE_USER_SITE and os.path.isdir(user_site):
         addsitedir(user_site, known_paths)
     if ENABLE_USER_SITE:
         for dist_libdir in ("local/lib", "lib"):
             user_site = os.path.join(USER_BASE, dist_libdir,
                                      "python" + sys.version[:3],
                                      "dist-packages")
             if os.path.isdir(user_site):
                 addsitedir(user_site, known_paths)
     return known_paths

 def getsitepackages():
     """Returns a list containing all global site-packages directories
     (and possibly site-python).

     For each directory present in the global ``PREFIXES``, this function
     will find its `site-packages` subdirectory depending on the system
     environment, and will return a list of full paths.
     """
     sitepackages = []
     seen = set()

     for prefix in PREFIXES:
         if not prefix or prefix in seen:
             continue
         seen.add(prefix)

         if sys.platform in ('os2emx', 'riscos'):
             sitepackages.append(os.path.join(prefix, "Lib", "site-packages"))
         elif os.sep == '/':
             sitepackages.append(os.path.join(prefix, "local/lib",
                                         "python" + sys.version[:3],
                                         "dist-packages"))
             sitepackages.append(os.path.join(prefix, "lib",
                                         "python" + sys.version[:3],
                                         "dist-packages"))
         else:
             sitepackages.append(prefix)
             sitepackages.append(os.path.join(prefix, "lib", "site-packages"))
         if sys.platform == "darwin":
             # for framework builds *only* we add the standard Apple
             # locations.
             from sysconfig import get_config_var
             framework = get_config_var("PYTHONFRAMEWORK")
             if framework:
                 sitepackages.append(
                         os.path.join("/Library", framework,
                             sys.version[:3], "site-packages"))
     return sitepackages

 def addsitepackages(known_paths):
     """Add site-packages (and possibly site-python) to sys.path"""
     for sitedir in getsitepackages():
         if os.path.isdir(sitedir):
             addsitedir(sitedir, known_paths)

     return known_paths

 def setBEGINLIBPATH():
     """The OS/2 EMX port has optional extension modules that do double duty
     as DLLs (and must use the .DLL file extension) for other extensions.
     The library search path needs to be amended so these will be found
     during module import.  Use BEGINLIBPATH so that these are at the start
     of the library search path.

     """
     dllpath = os.path.join(sys.prefix, "Lib", "lib-dynload")
     libpath = os.environ['BEGINLIBPATH'].split(';')
     if libpath[-1]:
         libpath.append(dllpath)
     else:
         libpath[-1] = dllpath
     os.environ['BEGINLIBPATH'] = ';'.join(libpath)


 def setquit():
     """Define new builtins 'quit' and 'exit'.

     These are objects which make the interpreter exit when called.
     The repr of each object contains a hint at how it works.

     """
     if os.sep == ':':
         eof = 'Cmd-Q'
     elif os.sep == '\\':
         eof = 'Ctrl-Z plus Return'
     else:
         eof = 'Ctrl-D (i.e. EOF)'

     class Quitter(object):
         def __init__(self, name):
             self.name = name
         def __repr__(self):
             return 'Use %s() or %s to exit' % (self.name, eof)
         def __call__(self, code=None):
             # Shells like IDLE catch the SystemExit, but listen when their
             # stdin wrapper is closed.
             try:
                 sys.stdin.close()
             except:
                 pass
             raise SystemExit(code)
     __builtin__.quit = Quitter('quit')
     __builtin__.exit = Quitter('exit')


 class _Printer(object):
     """interactive prompt objects for printing the license text, a list of
     contributors and the copyright notice."""

     MAXLINES = 23

     def __init__(self, name, data, files=(), dirs=()):
         self.__name = name
         self.__data = data
         self.__files = files
         self.__dirs = dirs
         self.__lines = None

     def __setup(self):
         if self.__lines:
             return
         data = None
         for dir in self.__dirs:
             for filename in self.__files:
                 filename = os.path.join(dir, filename)
                 try:
                     fp = file(filename, "rU")
                     data = fp.read()
                     fp.close()
                     break
                 except IOError:
                     pass
             if data:
                 break
         if not data:
             data = self.__data
         self.__lines = data.split('\n')
         self.__linecnt = len(self.__lines)

     def __repr__(self):
         self.__setup()
         if len(self.__lines) <= self.MAXLINES:
             return "\n".join(self.__lines)
         else:
             return "Type %s() to see the full %s text" % ((self.__name,)*2)

     def __call__(self):
         self.__setup()
         prompt = 'Hit Return for more, or q (and Return) to quit: '
         lineno = 0
         while 1:
             try:
                 for i in range(lineno, lineno + self.MAXLINES):
                     print self.__lines[i]
             except IndexError:
                 break
             else:
                 lineno += self.MAXLINES
                 key = None
                 while key is None:
                     key = raw_input(prompt)
                     if key not in ('', 'q'):
                         key = None
                 if key == 'q':
                     break

 def setcopyright():
     """Set 'copyright' and 'credits' in __builtin__"""
     __builtin__.copyright = _Printer("copyright", sys.copyright)
     if sys.platform[:4] == 'java':
         __builtin__.credits = _Printer(
             "credits",
             "Jython is maintained by the Jython developers (www.jython.org).")
     else:
         __builtin__.credits = _Printer("credits", """\
     Thanks to CWI, CNRI, BeOpen.com, Zope Corporation and a cast of thousands
     for supporting Python development.  See www.python.org for more information.""")
     here = os.path.dirname(os.__file__)
     __builtin__.license = _Printer(
         "license", "See https://www.python.org/psf/license/",
         ["LICENSE.txt", "LICENSE"],
         [os.path.join(here, os.pardir), here, os.curdir])


 class _Helper(object):
     """Define the builtin 'help'.
     This is a wrapper around pydoc.help (with a twist).

     """

     def __repr__(self):
         return "Type help() for interactive help, " \
                "or help(object) for help about object."
     def __call__(self, *args, **kwds):
         import pydoc
         return pydoc.help(*args, **kwds)

 def sethelper():
     __builtin__.help = _Helper()

 def aliasmbcs():
     """On Windows, some default encodings are not provided by Python,
     while they are always available as "mbcs" in each locale. Make
     them usable by aliasing to "mbcs" in such a case."""
     if sys.platform == 'win32':
         import locale, codecs
         enc = locale.getdefaultlocale()[1]
         if enc.startswith('cp'):            # "cp***" ?
             try:
                 codecs.lookup(enc)
             except LookupError:
                 import encodings
                 encodings._cache[enc] = encodings._unknown
                 encodings.aliases.aliases[enc] = 'mbcs'

 def setencoding():
     """Set the string encoding used by the Unicode implementation.  The
     default is 'ascii', but if you're willing to experiment, you can
     change this."""
     encoding = "ascii" # Default value set by _PyUnicode_Init()
     if 0:
         # Enable to support locale aware default string encodings.
         import locale
         loc = locale.getdefaultlocale()
         if loc[1]:
             encoding = loc[1]
     if 0:
         # Enable to switch off string to Unicode coercion and implicit
         # Unicode to string conversion.
         encoding = "undefined"
     if encoding != "ascii":
         # On Non-Unicode builds this will raise an AttributeError...
         sys.setdefaultencoding(encoding) # Needs Python Unicode build !


 def execsitecustomize():
     """Run custom site specific code, if available."""
     try:
         import sitecustomize
     except ImportError:
         pass
     except Exception:
         if sys.flags.verbose:
             sys.excepthook(*sys.exc_info())
         else:
             print >>sys.stderr, \
                 "'import sitecustomize' failed; use -v for traceback"


 def execusercustomize():
     """Run custom user specific code, if available."""
     try:
         import usercustomize
     except ImportError:
         pass
     except Exception:
         if sys.flags.verbose:
             sys.excepthook(*sys.exc_info())
         else:
             print>>sys.stderr, \
                 "'import usercustomize' failed; use -v for traceback"


 def main():
     global ENABLE_USER_SITE

     abs__file__()
     known_paths = removeduppaths()
     if ENABLE_USER_SITE is None:
         ENABLE_USER_SITE = check_enableusersite()
     known_paths = addusersitepackages(known_paths)
     known_paths = addsitepackages(known_paths)
     if sys.platform == 'os2emx':
         setBEGINLIBPATH()
     setquit()
     setcopyright()
     sethelper()
     aliasmbcs()
     setencoding()
     execsitecustomize()
     if ENABLE_USER_SITE:
         execusercustomize()
     # Remove sys.setdefaultencoding() so that users cannot change the
     # encoding after initialization.  The test for presence is needed when
     # this module is run as a script, because this code is executed twice.
     if hasattr(sys, "setdefaultencoding"):
         del sys.setdefaultencoding

 main()

 def _script():
     help = """\
     %s [--user-base] [--user-site]

     Without arguments print some useful information
     With arguments print the value of USER_BASE and/or USER_SITE separated
     by '%s'.

     Exit codes with --user-base or --user-site:
 - user site directory is enabled
 - user site directory is disabled by user
 - uses site directory is disabled by super user
           or for security reasons
      >2 - unknown error
     """
     args = sys.argv[1:]
     if not args:
         print "sys.path = ["
         for dir in sys.path:
             print "    %r," % (dir,)
         print "]"
         print "USER_BASE: %r (%s)" % (USER_BASE,
             "exists" if os.path.isdir(USER_BASE) else "doesn't exist")
         print "USER_SITE: %r (%s)" % (USER_SITE,
             "exists" if os.path.isdir(USER_SITE) else "doesn't exist")
         print "ENABLE_USER_SITE: %r" %  ENABLE_USER_SITE
         sys.exit(0)

     buffer = []
     if '--user-base' in args:
         buffer.append(USER_BASE)
     if '--user-site' in args:
         buffer.append(USER_SITE)

     if buffer:
         print os.pathsep.join(buffer)
         if ENABLE_USER_SITE:
             sys.exit(0)
         elif ENABLE_USER_SITE is False:
             sys.exit(1)
         elif ENABLE_USER_SITE is None:
             sys.exit(2)
         else:
             sys.exit(3)
     else:
         import textwrap
         print textwrap.dedent(help % (sys.argv[0], os.pathsep))
         sys.exit(10)

 if __name__ == '__main__':
     _script()