- 第一个 Bilibili 的滑块验证
- 第二个 pyppeteer + asyncio
- 第三个 app抓取抖音粉丝id
- 第四个 scrapy_redis 抓取链家二手房
###布隆布隆过滤器代码, bloomfilter.py 并将此文件放置在scrapy_redis包下面 ###pip安装mmh3无法安装时，可改为国内豆瓣源 pip install mmh3 -i https://pypi.douban.com/simple/
# -*- coding: utf-8 -*-
import mmh3
import redis
import math
import time
class PyBloomFilter():
#内置100个随机种子
SEEDS = [543, 460, 171, 876, 796, 607, 650, 81, 837, 545, 591, 946, 846, 521, 913, 636, 878, 735, 414, 372,
344, 324, 223, 180, 327, 891, 798, 933, 493, 293, 836, 10, 6, 544, 924, 849, 438, 41, 862, 648, 338,
465, 562, 693, 979, 52, 763, 103, 387, 374, 349, 94, 384, 680, 574, 480, 307, 580, 71, 535, 300, 53,
481, 519, 644, 219, 686, 236, 424, 326, 244, 212, 909, 202, 951, 56, 812, 901, 926, 250, 507, 739, 371,
63, 584, 154, 7, 284, 617, 332, 472, 140, 605, 262, 355, 526, 647, 923, 199, 518]
#capacity是预先估计要去重的数量
#error_rate表示错误率
#conn表示redis的连接客户端
#key表示在redis中的键的名字前缀
def __init__(self, capacity=1000000000, error_rate=0.00000001, conn=None, key='BloomFilter'):
self.m = math.ceil(capacity*math.log2(math.e)*math.log2(1/error_rate)) #需要的总bit位数
self.k = math.ceil(math.log1p(2)*self.m/capacity) #需要最少的hash次数
self.mem = math.ceil(self.m/8/1024/1024) #需要的多少M内存
self.blocknum = math.ceil(self.mem/512) #需要多少个512M的内存块,value的第一个字符必须是ascii码，所有最多有256个内存块
self.seeds = self.SEEDS[0:self.k]
self.key = key
self.N = 2**31-1
self.redis = conn
# print(self.mem)
# print(self.k)
def add(self, value):
name = self.key + "_" + str(ord(value[0])%self.blocknum)
hashs = self.get_hashs(value)
for hash in hashs:
self.redis.setbit(name, hash, 1)
def is_exist(self, value):
name = self.key + "_" + str(ord(value[0])%self.blocknum)
hashs = self.get_hashs(value)
exist = True
for hash in hashs:
exist = exist & self.redis.getbit(name, hash)
return exist
def get_hashs(self, value):
hashs = list()
for seed in self.seeds:
hash = mmh3.hash(value, seed)
if hash >= 0:
hashs.append(hash)
else:
hashs.append(self.N - hash)
return hashs
pool = redis.ConnectionPool(host='127.0.0.1', port=6379, db=3)
conn = redis.StrictRedis(connection_pool=pool)
if __name__ == "__main__":
bf = PyBloomFilter(conn=conn)
bf.add('www.lianjia.com')
print(bf.is_exist('www.lianjia.com'))###修改scrapy_redis包下的 dupefilter.py 文件，改为
import logging
import time
from scrapy.dupefilters import BaseDupeFilter
from scrapy.utils.request import request_fingerprint
from . import defaults
from .connection import get_redis_from_settings
from .bloomfilter import conn,PyBloomFilter #导入布隆过滤器
logger = logging.getLogger(__name__)
# TODO: Rename class to RedisDupeFilter.
class RFPDupeFilter(BaseDupeFilter):
"""Redis-based request duplicates filter.
This class can also be used with default Scrapy's scheduler.
"""
logger = logger
def __init__(self, server, key, debug=False):
"""Initialize the duplicates filter.
Parameters
----------
server : redis.StrictRedis
The redis server instance.
key : str
Redis key Where to store fingerprints.
debug : bool, optional
Whether to log filtered requests.
"""
self.server = server
self.key = key
self.debug = debug
self.logdupes = True
# 集成布隆过滤器
self.bf = PyBloomFilter(conn=conn, key=key) # 利用连接池连接Redis
@classmethod
def from_settings(cls, settings):
"""Returns an instance from given settings.
This uses by default the key ``dupefilter:<timestamp>``. When using the
``scrapy_redis.scheduler.Scheduler`` class, this method is not used as
it needs to pass the spider name in the key.
Parameters
----------
settings : scrapy.settings.Settings
Returns
-------
RFPDupeFilter
A RFPDupeFilter instance.
"""
server = get_redis_from_settings(settings)
# XXX: This creates one-time key. needed to support to use this
# class as standalone dupefilter with scrapy's default scheduler
# if scrapy passes spider on open() method this wouldn't be needed
# TODO: Use SCRAPY_JOB env as default and fallback to timestamp.
key = defaults.DUPEFILTER_KEY % {'timestamp': int(time.time())}
debug = settings.getbool('DUPEFILTER_DEBUG')
return cls(server, key=key, debug=debug)
@classmethod
def from_crawler(cls, crawler):
"""Returns instance from crawler.
Parameters
----------
crawler : scrapy.crawler.Crawler
Returns
-------
RFPDupeFilter
Instance of RFPDupeFilter.
"""
return cls.from_settings(crawler.settings)
def request_seen(self, request):
"""Returns True if request was already seen.
Parameters
----------
request : scrapy.http.Request
Returns
-------
bool
"""
fp = self.request_fingerprint(request)
# 集成布隆过滤器
if self.bf.is_exist(fp): # 判断如果域名在Redis里存在
return True
else:
self.bf.add(fp) # 如果不存在，将域名添加到Redis
return False
# This returns the number of values added, zero if already exists.
# added = self.server.sadd(self.key, fp)
# return added == 0
def request_fingerprint(self, request):
"""Returns a fingerprint for a given request.
Parameters
----------
request : scrapy.http.Request
Returns
-------
str
"""
return request_fingerprint(request)
def close(self, reason=''):
"""Delete data on close. Called by Scrapy's scheduler.
Parameters
----------
reason : str, optional
"""
self.clear()
def clear(self):
"""Clears fingerprints data."""
self.server.delete(self.key)
def log(self, request, spider):
"""Logs given request.
Parameters
----------
request : scrapy.http.Request
spider : scrapy.spiders.Spider
"""
if self.debug:
msg = "Filtered duplicate request: %(request)s"
self.logger.debug(msg, {'request': request}, extra={'spider': spider})
elif self.logdupes:
msg = ("Filtered duplicate request %(request)s"
" - no more duplicates will be shown"
" (see DUPEFILTER_DEBUG to show all duplicates)")
self.logger.debug(msg, {'request': request}, extra={'spider': spider})
self.logdupes = False