Scrapy-Redis結合POST請求獲取數據的方法示例

前言

通常我們在一個站站點進行采集的時候，如果是小站的話 我們使用scrapy本身就可以滿足。

但是如果在面對一些比較大型的站點的時候，單個scrapy就顯得力不從心了。

要是我們能夠多個Scrapy一起采集該多好啊 人多力量大。

很遺憾Scrapy官方并不支持多個同時采集一個站點，雖然官方給出一個方法：

**將一個站點的分割成幾部分 交給不同的scrapy去采集**

似乎是個解決辦法，但是很麻煩誒！畢竟分割很麻煩的哇

下面就改輪到我們的額主角Scrapy-Redis登場了！

能看到這篇文章的小伙伴肯定已經知道什么是Scrapy以及Scrapy-Redis了，基礎概念這里就不再介紹。默認情況下Scrapy-Redis是發送GET請求獲取數據的，對于某些使用POST請求的情況需要重寫make_request_from_data函數即可，但奇怪的是居然沒在網上搜到簡潔明了的答案，或許是太簡單了？。

這里我以httpbin.org這個網站為例，首先在settings.py中添加所需配置，這里需要根據實際情況進行修改：

SCHEDULER = "scrapy_redis.scheduler.Scheduler" #啟用Redis調度存儲請求隊列
SCHEDULER_PERSIST = True #不清除Redis隊列、這樣可以暫停/恢復 爬取
DUPEFILTER_CLASS = "scrapy_redis.dupefilter.RFPDupeFilter" #確保所有的爬蟲通過Redis去重
SCHEDULER_QUEUE_CLASS = 'scrapy_redis.queue.SpiderPriorityQueue'
REDIS_URL = "redis://127.0.0.1:6379"

爬蟲代碼如下：

# -*- coding: utf-8 -*-
import scrapy
from scrapy_redis.spiders import RedisSpider


class HpbSpider(RedisSpider):
 name = 'hpb'
 redis_key = 'test_post_data'

 def make_request_from_data(self, data):
  """Returns a Request instance from data coming from Redis.
  By default, ``data`` is an encoded URL. You can override this method to
  provide your own message decoding.
  Parameters
  ----------
  data : bytes
   Message from redis.
  """
  return scrapy.FormRequest("https://www.httpbin.org/post",
         formdata={"data":data},callback=self.parse)

 def parse(self, response):
  print(response.body)

這里為了簡單直接進行輸出，真實使用時可以結合pipeline寫數據庫等。

然后啟動爬蟲程序scrapy crawl hpb，由于我們還沒向test_post_data中寫數據，所以啟動后程序進入等待狀態。然后模擬向隊列寫數據：

import redis
rd = redis.Redis('127.0.0.1',port=6379,db=0)
for _ in range(1000):
 rd.lpush('test_post_data',_)

此時可以看到爬蟲已經開始獲取程序了：

2019-05-06 16:30:21 [hpb] DEBUG: Read 8 requests from 'test_post_data'
2019-05-06 16:30:21 [scrapy.core.engine] DEBUG: Crawled (200) <POST https://www.httpbin.org/post> (referer: None)
2019-05-06 16:30:21 [scrapy.core.engine] DEBUG: Crawled (200) <POST https://www.httpbin.org/post> (referer: None)
2019-05-06 16:30:21 [scrapy.core.engine] DEBUG: Crawled (200) <POST https://www.httpbin.org/post> (referer: None)
2019-05-06 16:30:21 [scrapy.core.engine] DEBUG: Crawled (200) <POST https://www.httpbin.org/post> (referer: None)
2019-05-06 16:30:21 [scrapy.core.engine] DEBUG: Crawled (200) <POST https://www.httpbin.org/post> (referer: None)
2019-05-06 16:30:21 [scrapy.core.engine] DEBUG: Crawled (200) <POST https://www.httpbin.org/post> (referer: None)
2019-05-06 16:30:21 [scrapy.core.engine] DEBUG: Crawled (200) <POST https://www.httpbin.org/post> (referer: None)
2019-05-06 16:30:21 [scrapy.core.engine] DEBUG: Crawled (200) <POST https://www.httpbin.org/post> (referer: None)
b'{\n  "args": {}, \n  "data": "", \n  "files": {}, \n  "form": {\n    "data": "0"\n  }, \n  "headers": {\n    "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", \n    "Accept-Encoding": "gzip,deflate", \n    "Accept-Language": "en", \n    "Content-Length": "6", \n    "Content-Type": "application/x-www-form-urlencoded", \n    "Host": "www.httpbin.org", \n    "User-Agent": "Scrapy/1.5.1 (+https://scrapy.org)"\n  }, \n  "json": null, \n  "origin": "1.2.3.48, 1.2.3.48", \n  "url": "https://www.httpbin.org/post"\n}\n'
b'{\n  "args": {}, \n  "data": "", \n  "files": {}, \n  "form": {\n    "data": "1"\n  }, \n  "headers": {\n    "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", \n    "Accept-Encoding": "gzip,deflate", \n    "Accept-Language": "en", \n    "Content-Length": "6", \n    "Content-Type": "application/x-www-form-urlencoded", \n    "Host": "www.httpbin.org", \n    "User-Agent": "Scrapy/1.5.1 (+https://scrapy.org)"\n  }, \n  "json": null, \n  "origin": "1.2.3.48, 1.2.3.48", \n  "url": "https://www.httpbin.org/post"\n}\n'
b'{\n  "args": {}, \n  "data": "", \n  "files": {}, \n  "form": {\n    "data": "3"\n  }, \n  "headers": {\n    "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", \n    "Accept-Encoding": "gzip,deflate", \n    "Accept-Language": "en", \n    "Content-Length": "6", \n    "Content-Type": "application/x-www-form-urlencoded", \n    "Host": "www.httpbin.org", \n    "User-Agent": "Scrapy/1.5.1 (+https://scrapy.org)"\n  }, \n  "json": null, \n  "origin": "1.2.3.48, 1.2.3.48", \n  "url": "https://www.httpbin.org/post"\n}\n'
b'{\n  "args": {}, \n  "data": "", \n  "files": {}, \n  "form": {\n    "data": "2"\n  }, \n  "headers": {\n    "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", \n    "Accept-Encoding": "gzip,deflate", \n    "Accept-Language": "en", \n    "Content-Length": "6", \n    "Content-Type": "application/x-www-form-urlencoded", \n    "Host": "www.httpbin.org", \n    "User-Agent": "Scrapy/1.5.1 (+https://scrapy.org)"\n  }, \n  "json": null, \n  "origin": "1.2.3.48, 1.2.3.48", \n  "url": "https://www.httpbin.org/post"\n}\n'
b'{\n  "args": {}, \n  "data": "", \n  "files": {}, \n  "form": {\n    "data": "4"\n  }, \n  "headers": {\n    "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", \n    "Accept-Encoding": "gzip,deflate", \n    "Accept-Language": "en", \n    "Content-Length": "6", \n    "Content-Type": "application/x-www-form-urlencoded", \n    "Host": "www.httpbin.org", \n    "User-Agent": "Scrapy/1.5.1 (+https://scrapy.org)"\n  }, \n  "json": null, \n  "origin": "1.2.3.48, 1.2.3.48", \n  "url": "https://www.httpbin.org/post"\n}\n'
b'{\n  "args": {}, \n  "data": "", \n  "files": {}, \n  "form": {\n    "data": "5"\n  }, \n  "headers": {\n    "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", \n    "Accept-Encoding": "gzip,deflate", \n    "Accept-Language": "en", \n    "Content-Length": "6", \n    "Content-Type": "application/x-www-form-urlencoded", \n    "Host": "www.httpbin.org", \n    "User-Agent": "Scrapy/1.5.1 (+https://scrapy.org)"\n  }, \n  "json": null, \n  "origin": "1.2.3.48, 1.2.3.48", \n  "url": "https://www.httpbin.org/post"\n}\n'
b'{\n  "args": {}, \n  "data": "", \n  "files": {}, \n  "form": {\n    "data": "6"\n  }, \n  "headers": {\n    "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", \n    "Accept-Encoding": "gzip,deflate", \n    "Accept-Language": "en", \n    "Content-Length": "6", \n    "Content-Type": "application/x-www-form-urlencoded", \n    "Host": "www.httpbin.org", \n    "User-Agent": "Scrapy/1.5.1 (+https://scrapy.org)"\n  }, \n  "json": null, \n  "origin": "1.2.3.48, 1.2.3.48", \n  "url": "https://www.httpbin.org/post"\n}\n'
b'{\n  "args": {}, \n  "data": "", \n  "files": {}, \n  "form": {\n    "data": "7"\n  }, \n  "headers": {\n    "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", \n    "Accept-Encoding": "gzip,deflate", \n    "Accept-Language": "en", \n    "Content-Length": "6", \n    "Content-Type": "application/x-www-form-urlencoded", \n    "Host": "www.httpbin.org", \n    "User-Agent": "Scrapy/1.5.1 (+https://scrapy.org)"\n  }, \n  "json": null, \n  "origin": "1.2.3.48, 1.2.3.48", \n  "url": "https://www.httpbin.org/post"\n}\n'
2019-05-06 16:31:09 [scrapy.extensions.logstats] INFO: Crawled 1001 pages (at 280 pages/min), scraped 0 items (at 0 items/min)
2019-05-06 16:32:09 [scrapy.extensions.logstats] INFO: Crawled 1001 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2019-05-06 16:33:09 [scrapy.extensions.logstats] INFO: Crawled 1001 pages (at 0 pages/min), scraped 0 items (at 0 items/min)

至于數據重復的問題，如果POST的數據重復，這個請求就不會發送出去。如果有特殊情況POST發送同樣的數據回得到不同返回值，添加dont_filter=True是沒用的，在RFPDupeFilter類中并沒考慮這個參數，需要重寫。

總結

以上就是這篇文章的全部內容了，希望本文的內容對大家的學習或者工作具有一定的參考學習價值，謝謝大家對億速云的支持。