Scrapyのspiderベースソース

Scrapyのspiderベースソース
spiderのサブクラスがインスタンス化されると、_init __ のコードが実行されるのでnameとstar_を設定する必要がありますurlの2つのプロパティ.しかしSpiderのサブクラスはインスタンス化された後すぐにネットワークに登ることはなくstart_requestsが呼び出されると、クモは網登りを実行します.最初にWebサイトにアクセスしたREquestsオブジェクトを変更したい場合は、start_を書き換えることができます.requests関数.

"""
Base class for Scrapy spiders

See documentation in docs/topics/spiders.rst
"""
import logging
import warnings

from scrapy import signals
from scrapy.http import Request
from scrapy.utils.trackref import object_ref
from scrapy.utils.url import url_is_from_spider
from scrapy.utils.deprecate import create_deprecated_class
from scrapy.exceptions import ScrapyDeprecationWarning
from scrapy.utils.deprecate import method_is_overridden


class Spider(object_ref):
    """
    Base class for scrapy spiders. All spiders must inherit from this
    class.
    """

    name = None
    custom_settings = None

    def __init__(self, name=None, **kwargs):
        if name is not None:
            self.name = name
        elif not getattr(self, 'name', None):
            raise ValueError("%s must have a name" % type(self).__name__)
        self.__dict__.update(kwargs)
        if not hasattr(self, 'start_urls'):
            self.start_urls = []

    @property
    def logger(self):
        logger = logging.getLogger(self.name)
        return logging.LoggerAdapter(logger, {'spider': self})

    def log(self, message, level=logging.DEBUG, **kw):
        """
        Log the given message at the given log level
        This helper wraps a log call to the logger within the spider, but you
        can use it directly (e.g. Spider.logger.info('msg')) or use any other
        Python logger too.
        """
        self.logger.log(level, message, **kw)

    @classmethod
    def from_crawler(cls, crawler, *args, **kwargs):
        spider = cls(*args, **kwargs)
        spider._set_crawler(crawler)
        return spider

    def set_crawler(self, crawler):
        warnings.warn("set_crawler is deprecated, instantiate and bound the "
                      "spider to this crawler with from_crawler method "
                      "instead.",
                      category=ScrapyDeprecationWarning, stacklevel=2)
        assert not hasattr(self, 'crawler'), "Spider already bounded to a " \
                                             "crawler"
        self._set_crawler(crawler)

    def _set_crawler(self, crawler):
        self.crawler = crawler
        self.settings = crawler.settings
        crawler.signals.connect(self.close, signals.spider_closed)

    def start_requests(self):
        cls = self.__class__
        if method_is_overridden(cls, Spider, 'make_requests_from_url'):
            warnings.warn(
                "Spider.make_requests_from_url method is deprecated; it "
                "won't be called in future Scrapy releases. Please "
                "override Spider.start_requests method instead (see %s.%s)." % (
                    cls.__module__, cls.__name__
                ),
            )
            for url in self.start_urls:
                yield self.make_requests_from_url(url)
        else:
            for url in self.start_urls:
                yield Request(url, dont_filter=True)

    def make_requests_from_url(self, url):
        """ This method is deprecated. """
        return Request(url, dont_filter=True)

    def parse(self, response):
        raise NotImplementedError

    @classmethod
    def update_settings(cls, settings):
        settings.setdict(cls.custom_settings or {}, priority='spider')

    @classmethod
    def handles_request(cls, request):
        return url_is_from_spider(request.url, cls)

    @staticmethod
    def close(spider, reason):
        closed = getattr(spider, 'closed', None)
        if callable(closed):
            return closed(reason)

    def __str__(self):
        return "" % (type(self).__name__, self.name, id(self))

    __repr__ = __str__

start_の変更requests、呼び出し時にpostでログイン:

def start_requests (self):
    return [scrapy.FormRequest("http://www.wxample.com/login",
                               formadta = {'user':'jon','pass':'secret'},
                               callback = self.logged_in)]
'''
    URL        requests  。    request  start_requests()  ，
    i  url request。
'''

汎用クモ
scrapyは4つの共通のクモを提供していくつかの普遍的な爬取任務を処理する:XML FeedSpider--XMLドキュメントフォーマットのクモベースクラスCSVFeedSpider--CSVファイルの爬取CrawlSpider--間接的な爬取を行うクモSitemapSpider--Sitemap.xmlファイルとウェブサイトに入って深くネットを登るクモ