scrapy百度POI爬虫实战项目代码(五)

素颜马尾好姑娘i 2022-12-18 09:54 108阅读 0赞

middlewares.py ------------------------------------------------
    # Define here the models for your spider middleware
    #
    # See documentation in:
    # https://docs.scrapy.org/en/latest/topics/spider-middleware.html
    
    from scrapy import signals
    
    # useful for handling different item types with a single interface
    from itemadapter import is_item, ItemAdapter
    import random
    from scrapy.utils.project import get_project_settings
    
    class RandomUserAgent:
        def process_request(self, request, spider):
            settings=get_project_settings()
            USER_AGENT_LIST=settings.getlist("USER_AGENT_LIST")
            ua = random.choice(USER_AGENT_LIST)
            request.headers.setdefault('User-Agent', ua)
    
    class MapbarspiderSpiderMiddleware:
        # Not all methods need to be defined. If a method is not defined,
        # scrapy acts as if the spider middleware does not modify the
        # passed objects.
    
    @classmethod
    def from_crawler(cls, crawler):
        # This method is used by Scrapy to create your spiders.
        s = cls()
        crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
        return s
    
    def process_spider_input(self, response, spider):
        # Called for each response that goes through the spider
        # middleware and into the spider.
    
        # Should return None or raise an exception.
        return None
    
    def process_spider_output(self, response, result, spider):
        # Called with the results returned from the Spider, after
        # it has processed the response.
    
        # Must return an iterable of Request, or item objects.
        for i in result:
            yield i
    
    def process_spider_exception(self, response, exception, spider):
        # Called when a spider or process_spider_input() method
        # (from other spider middleware) raises an exception.
    
        # Should return either None or an iterable of Request or item objects.
        pass
    
    def process_start_requests(self, start_requests, spider):
        # Called with the start requests of the spider, and works
        # similarly to the process_spider_output() method, except
        # that it doesn’t have a response associated.
    
        # Must return only requests (not items).
        for r in start_requests:
            yield r
    
    def spider_opened(self, spider):
        spider.logger.info('Spider opened: %s' % spider.name)
    
    
    class MapbarspiderDownloaderMiddleware:
        # Not all methods need to be defined. If a method is not defined,
        # scrapy acts as if the downloader middleware does not modify the
        # passed objects.
    
    @classmethod
    def from_crawler(cls, crawler):
        # This method is used by Scrapy to create your spiders.
        s = cls()
        crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
        return s
    
    def process_request(self, request, spider):
        # Called for each request that goes through the downloader
        # middleware.
    
        # Must either:
        # - return None: continue processing this request
        # - or return a Response object
        # - or return a Request object
        # - or raise IgnoreRequest: process_exception() methods of
        #   installed downloader middleware will be called
        return None
    
    def process_response(self, request, response, spider):
        # Called with the response returned from the downloader.
    
        # Must either;
        # - return a Response object
        # - return a Request object
        # - or raise IgnoreRequest
        return response
    
    def process_exception(self, request, exception, spider):
        # Called when a download handler or a process_request()
        # (from other downloader middleware) raises an exception.
    
        # Must either:
        # - return None: continue processing this exception
        # - return a Response object: stops process_exception() chain
        # - return a Request object: stops process_exception() chain
        pass
    
    def spider_opened(self, spider):
        spider.logger.info('Spider opened: %s' % spider.name)