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"""Download handlers for different schemes"""
from twisted.internet import defer
from scrapy.exceptions import NotSupported, NotConfigured
from scrapy.utils.httpobj import urlparse_cached
from scrapy.utils.misc import load_object
from scrapy import signals
class DownloadHandlers(object):
def __init__(self, crawler):
self._handlers = {}
self._notconfigured = {}
handlers = crawler.settings.get('DOWNLOAD_HANDLERS_BASE')
handlers.update(crawler.settings.get('DOWNLOAD_HANDLERS', {}))
for scheme, clspath in handlers.iteritems():
# Allow to disable a handler just like any other
# component (extension, middleware, etc).
if clspath is None:
continue
cls = load_object(clspath)
try:
dh = cls(crawler.settings)
except NotConfigured as ex:
self._notconfigured[scheme] = str(ex)
else:
self._handlers[scheme] = dh
crawler.signals.connect(self._close, signals.engine_stopped)
def download_request(self, request, spider):
scheme = urlparse_cached(request).scheme
try:
handler = self._handlers[scheme].download_request
except KeyError:
msg = self._notconfigured.get(scheme, \
'no handler available for that scheme')
raise NotSupported("Unsupported URL scheme '%s': %s" % (scheme, msg))
return handler(request, spider)
@defer.inlineCallbacks
def _close(self, *_a, **_kw):
for dh in self._handlers.values():
if hasattr(dh, 'close'):
yield dh.close()
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