Question

我可以暂停网络爬网程序吗？我使用下载延迟设置，以延迟URL之间的延迟，但是我也想暂停代理之间的程序。我使用多个代理来抓取多个URL。每个代理服务器都有4-5个URL。因此，在将所有网址抓取到所述代理后，我希望它暂停一定的时间（可能是10-15分钟），然后再转到下一个代理并抓取这些URL。

# Import from other python files and scrapy files and the needed csv file containing all URLs/proxies/ua
import csv
import scrapy
from scrapy.spiders import Spider
from scrapy_splash import SplashRequest
from ..items import GameItem
from random import randint
from time import sleep
from scrapy.http import Request
##########################          SPALSHSPIDER.PY OVERVIEW      #####################################################
# process the csv file so the url + ip address + useragent pairs are the same as defined in the file
# returns a list of dictionaries, example:
# [ {'url': 'http://www.starcitygames.com/catalog/category/Rivals%20of%20Ixalan',
#    'ip': 'http://204.152.114.244:8050',
#    'ua': "Mozilla/5.0 (BlackBerry; U; BlackBerry 9320; en-GB) AppleWebKit/534.11"},
#    ...
# ]
# plus python file also scrapes all URLs returning needed info and goes to all apges associated with URL by clicking next button

# Function to read csv file that contains URLs that are paried with proxies and user agents
def process_csv(csv_file):
    # Initialize data
    data = []
    # Initialize reader
    reader = csv.reader(csv_file)
    next(reader)

    # While inside csv file and not at end of csv file
    for fields in reader:

        # Set URL
        if fields[0] != "":
            url = fields[0]
        else:
            continue # skip the whole row if the url column is empty
        #Set proxy and pair with correct URL
        if fields[1] != "":
            ip = "http://" + fields[1] + ":8050" # adding http and port because this is the needed scheme
        # Set user agent and pair with correct URL
        if fields[2] != "":
            useragent = fields[2]
        # Put all three together
        data.append({"url": url, "ip": ip, "ua": useragent})
    # Return URL paried with ua and proxy
    return data

# Spider class
class MySpider(Spider):

    # Name of Spider
    name = 'splash_spider'
    # getting all the url + ip address + useragent pairs then request them
    def start_requests(self):


        # get the file path of the csv file that contains the pairs from the settings.py
        with open(self.settings["PROXY_CSV_FILE"], mode="r") as csv_file:
           # requests is a list of dictionaries like this -> {url: str, ua: str, ip: str}
            requests = process_csv(csv_file)
            for i, req in enumerate(requests):
                x = len(requests) - i
                # Return needed url with set delay of 3 seconds
                yield SplashRequest(url=req["url"], callback=self.parse, args={"wait": 3},
                        # Pair with user agent specified in csv file
                        headers={"User-Agent": req["ua"]},
                        # Sets splash_url to whatever the current proxy that goes with current URL  is instead of actual splash url
                        splash_url = req["ip"],
                        priority = x,
                        meta={'priority': x}
                        )
    # Scraping function that will scrape URLs for specified information
    def parse(self, response):
        # Initialize item to function GameItem located in items.py, will be called multiple times
        item = GameItem()
        # Initialize saved_name
        saved_name = ""
        # Extract card category from URL using html code from website that identifies the category.  Will be outputted before rest of data
        item["Category"] = response.css("span.titletext::text").get()
        # For loop to loop through HTML code until all necessary data has been scraped
        for game in response.css("tr[class^=deckdbbody]"):
            # Initialize saved_name to the extracted card name
            saved_name  = game.css("a.card_popup::text").get() or saved_name
            # Now call item and set equal to saved_name and strip leading '\n' from output
            item["Card_Name"] = saved_name.strip()
            # Check to see if output is null, in the case that there are two different conditions for one card
            if item["Card_Name"] != None:
                # If not null than store value in saved_name
                saved_name = item["Card_Name"].strip()
            # If null then set null value to previous card name since if there is a null value you should have the same card name twice
            else:
                item["Card_Name"] = saved_name
            # Call item again in order to extract the condition, stock, and price using the corresponding html code from the website
            item["Condition"] = game.css("td[class^=deckdbbody].search_results_7 a::text").get()
            item["Stock"] = game.css("td[class^=deckdbbody].search_results_8::text").get()
            item["Price"] = game.css("td[class^=deckdbbody].search_results_9::text").get()
            if item["Price"] == None:
                item["Price"] = game.css("td[class^=deckdbbody].search_results_9 span[style*='color:red']::text").get()

            # Return values
            yield item
            # Finds next page button
        next_page = response.xpath('//a[contains(., "- Next>>")]/@href').get()
        # If it exists and there is a next page enter if statement
        if next_page is not None:
            # Go to next page
            yield response.follow(next_page, self.parse)

Answer 1

是的，您可以在您的DownloadMiddleware中像这样使用crawler.engine.pause()和crawler.engine.unpause()一段时间

class cRetry(RetryMiddleware):

    def __init__(self, crawler):
        super(cRetry, self).__init__(crawler.settings)
        self.crawler = crawler

    @classmethod
    def from_crawler(cls, crawler):
        return cls(crawler)

   def process_response(self, request, response, spider):
        if Need to Pause:

            self.crawler.engine.pause()
            time.sleep(10)
            self.crawler.engine.unpause()

        return response

如何暂停网页抓取程序

1 个答案: