Scrapy settings.py配置文件详解

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原创最新推荐文章于 2026-10-02 14:16:36 发布 911 阅读 AI 写同款· GEO 优化 ›
二十一：scrapy中设置下载延时与自动限速 1、DOWNLOAD_DELAY 　　在settings中设置　　DOWNLOAD_DELAY=2　　#延时2秒，不能动态改变，导致访问延时都差不多，也容易被发现 2、RANDOMIZE_DOWNLOAD_DELAY 　　在settings中设置　　RANDOMIZE_DOWNLOAD_DELAY=True　　# 启用后，当从相同的网站获取数据时，Scrapy将会等待一个随机的值，延迟时间为0.... 阅读详情
# -*- coding: utf-8 -*-# Scrapy settings for demo1 project 
# 
# For simplicity, this file contains only settings considered important or 
# commonly used. You can find more settings consulting the documentation: 
# 
# http://doc.scrapy.org/en/latest/topics/settings.html 
# http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html 
# http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.htmlBOT_NAME = 'demo1' #Scrapy项目的名字,这将用来构造默认 User-Agent,同时也用来log,当您使用 startproject 命令创建项目时其也被自动赋值。SPIDER_MODULES = ['demo1.spiders'] #Scrapy搜索spider的模块列表 默认: [xxx.spiders] 
NEWSPIDER_MODULE = 'demo1.spiders' #使用 genspider 命令创建新spider的模块。默认: 'xxx.spiders' 
#爬取的默认User-Agent,除非被覆盖 
#USER_AGENT = 'demo1 (+http://www.yourdomain.com)'#如果启用,Scrapy将会采用 robots.txt策略 
ROBOTSTXT_OBEY = True#Scrapy downloader 并发请求(concurrent requests)的最大值,默认: 16 
#CONCURRENT_REQUESTS = 32#为同一网站的请求配置延迟(默认值:0) 
# See http://scrapy.readthedocs.org/en/latest/topics/settings.html#download-delay 
# See also autothrottle settings and docs 
#DOWNLOAD_DELAY = 3 下载器在下载同一个网站下一个页面前需要等待的时间,该选项可以用来限制爬取速度,减轻服务器压力。同时也支持小数:0.25 以秒为单位 
#下载延迟设置只有一个有效 
#CONCURRENT_REQUESTS_PER_DOMAIN = 16 对单个网站进行并发请求的最大值。 
#CONCURRENT_REQUESTS_PER_IP = 16 对单个IP进行并发请求的最大值。如果非0,则忽略 CONCURRENT_REQUESTS_PER_DOMAIN 设定,使用该设定。 也就是说,并发限制将针对IP,而不是网站。该设定也影响 DOWNLOAD_DELAY: 如果 CONCURRENT_REQUESTS_PER_IP 非0,下载延迟应用在IP而不是网站上。#禁用Cookie(默认情况下启用) 
#COOKIES_ENABLED = False#禁用Telnet控制台(默认启用) 
#TELNETCONSOLE_ENABLED = False #覆盖默认请求标头: 
#DEFAULT_REQUEST_HEADERS = { 
# 'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8', 
# 'Accept-Language': 'en', 
#}#启用或禁用蜘蛛中间件 
# See http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html 
#SPIDER_MIDDLEWARES = { 
#'demo1.middlewares.Demo1SpiderMiddleware': 543, 
#}#启用或禁用下载器中间件 
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html 
#DOWNLOADER_MIDDLEWARES = { 
#'demo1.middlewares.MyCustomDownloaderMiddleware': 543, 
#}#启用或禁用扩展程序 
# See http://scrapy.readthedocs.org/en/latest/topics/extensions.html 
#EXTENSIONS = { 
#'scrapy.extensions.telnet.TelnetConsole': None, 
#}#配置项目管道 
# See http://scrapy.readthedocs.org/en/latest/topics/item-pipeline.html 
#ITEM_PIPELINES = { 
#'demo1.pipelines.Demo1Pipeline': 300, 
#}#启用和配置AutoThrottle扩展(默认情况下禁用) 
# See http://doc.scrapy.org/en/latest/topics/autothrottle.html 
#AUTOTHROTTLE_ENABLED = True#初始下载延迟 
#AUTOTHROTTLE_START_DELAY = 5#在高延迟的情况下设置的最大下载延迟 
#AUTOTHROTTLE_MAX_DELAY = 60 
#Scrapy请求的平均数量应该并行发送每个远程服务器 
#AUTOTHROTTLE_TARGET_CONCURRENCY = 1.0#启用显示所收到的每个响应的调节统计信息:
#AUTOTHROTTLE_DEBUG = False#启用和配置HTTP缓存(默认情况下禁用) 
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html#httpcache-middleware-settings 
#HTTPCACHE_ENABLED = True 
#HTTPCACHE_EXPIRATION_SECS = 0 
#HTTPCACHE_DIR = 'httpcache' 
#HTTPCACHE_IGNORE_HTTP_CODES = [] 
#HTTPCACHE_STORAGE = 'scrapy.extensions.httpcache.FilesystemCacheStorage' 
解释几个参数:
ROBOTSTXT_OBEY = True-----------是否遵守robots.txt
CONCURRENT_REQUESTS = 16-----------开启线程数量,默认16
AUTOTHROTTLE_START_DELAY = 3-----------开始下载时限速并延迟时间
AUTOTHROTTLE_MAX_DELAY = 60-----------高并发请求时最大延迟时间
最底下的几个:是否启用在本地缓存,如果开启会优先读取本地缓存,从而加快爬取速度,视情况而定
HTTPCACHE_ENABLED = True
HTTPCACHE_EXPIRATION_SECS = 0
HTTPCACHE_DIR = 'httpcache'
HTTPCACHE_IGNORE_HTTP_CODES = []
HTTPCACHE_STORAGE = 'scrapy.extensions.httpcache.FilesystemCacheStorage'
以上几个可以视项目需要开启,但是有两个参数最好每次都开启,而每次都是项目文件手动开启不免有些麻烦,最好是项目创建后就自动开启#DEFAULT_REQUEST_HEADERS = {#'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',#'Accept-Language': 'en',#}这个是浏览器请求头,很多网站都会检查客户端的headers,比如豆瓣就是每一个请求都检查headers的user_agent,否则只会返回403,可以开启#USER_AGENT = 'Chirco (+http://www.yourdomain.com)'这个是至关重要的,大部分服务器在请求快了会首先检查User_Agent,而scrapy默认的浏览器头是scrapy1.1 我们需要开启并且修改成浏览器头,如:Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/22.0.1207.1 Safari/537.1但是最好是这个USER-AGENT会随机自动更换最好了。
下面的代码可以从预先定义的user-agent的列表中随机选择一个来采集不同的页面
在settings.py中添加以下代码
DOWNLOADER_MIDDLEWARES = {
'scrapy.contrib.downloadermiddleware.useragent.UserAgentMiddleware' : None,
'randoms.rotate_useragent.RotateUserAgentMiddleware' :400
}
rotate_useragent的代码为:
# -*- coding: utf-8 -*-
import random
from scrapy.contrib.downloadermiddleware.useragent import UserAgentMiddlewareclass RotateUserAgentMiddleware(UserAgentMiddleware):
def __init__(self, user_agent=''):
self.user_agent = user_agentdef process_request(self, request, spider):
#这句话用于随机选择user-agent
ua = random.choice(self.user_agent_list)
if ua:
print('User-Agent:'+ua)
request.headers['User-Agent']=ua#the default user_agent_list composes chrome,I E,firefox,Mozilla,opera,netscape
user_agent_list = [/
"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/22.0.1207.1 Safari/537.1"/
"Mozilla/5.0 (X11; CrOS i686 2268.111.0) AppleWebKit/536.11 (KHTML, like Gecko) Chrome/20.0.1132.57 Safari/536.11",/
"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.6 (KHTML, like Gecko) Chrome/20.0.1092.0 Safari/536.6",/
"Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.6 (KHTML, like Gecko) Chrome/20.0.1090.0 Safari/536.6",/
"Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/19.77.34.5 Safari/537.1",/
"Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/536.5 (KHTML, like Gecko) Chrome/19.0.1084.9 Safari/536.5",/
"Mozilla/5.0 (Windows NT 6.0) AppleWebKit/536.5 (KHTML, like Gecko) Chrome/19.0.1084.36 Safari/536.5",/
"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3",/
"Mozilla/5.0 (Windows NT 5.1) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3",/
"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_0) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3",/
"Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1062.0 Safari/536.3",/
"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1062.0 Safari/536.3",/
"Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3",/
"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3",/
"Mozilla/5.0 (Windows NT 6.1) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3",/
"Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1061.0 Safari/536.3",/
"Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/535.24 (KHTML, like Gecko) Chrome/19.0.1055.1 Safari/535.24",/
"Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/535.24 (KHTML, like Gecko) Chrome/19.0.1055.1 Safari/535.24"
]
运行爬虫可以看到信息:
2017-04-16 00:07:40 [scrapy.extensions.telnet] DEBUG: Telnet console listening on 127.0.0.1:6023
User-Agent:Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3
2017-04-16 00:07:40 [scrapy.downloadermiddlewares.redirect] DEBUG: Redirecting (301) to <GET http://www.jianshu.com/robots.txt> from <GET http://jianshu.com/robots.txt>
User-Agent:Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/19.77.34.5 Safari/537.1
2017-04-16 00:07:41 [scrapy.core.engine] DEBUG: Crawled (200) <GET http://www.jianshu.com/robots.txt> (referer: None)
User-Agent:Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/535.24 (KHTML, like Gecko) Chrome/19.0.1055.1 Safari/535.24
2017-04-16 00:07:41 [scrapy.downloadermiddlewares.redirect] DEBUG: Redirecting (301) to <GET http://www.jianshu.com/> from <GET http://jianshu.com/>
User-Agent:Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1062.0 Safari/536.3也可以把user_agent_list放到settings文件中去:
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