平時寫爬蟲的時候並不需要設置setting裏所有的參數，今天心血來潮，花了點時間查了一下setting模塊創建後自動寫入的所有參數的含義，記錄一下。

• 模塊相關說明信息

# -*- coding: utf-8 -*-

# Scrapy settings for new_center 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.html
 

• 項目名字和爬蟲模塊說明，引擎根據這個信息找到爬蟲

BOT_NAME = ‘new_center‘  # 項目名字

SPIDER_MODULES = [‘new_center.spiders‘]
NEWSPIDER_MODULE = ‘new_center.spiders‘

• 瀏覽器的USER_AGENT，可以自定義偽裝。

# Crawl responsibly by identifying yourself (and your website) on the user-agent
#USER_AGENT = ‘new_center (+http://www.yourdomain.com)‘
 

• 是否遵守robots協議，默認是遵守的，可以改成False或將其註釋

# Obey robots.txt rules
ROBOTSTXT_OBEY = True

• 設置scrapy爬蟲最大的並發請求數量，默認是16

# Configure maximum concurrent requests performed by Scrapy (default: 16)
#CONCURRENT_REQUESTS = 32

• 設置對訪問同一個網站進行請求的延時時間，默認是0.

# Configure a delay for requests for the same website (default: 0)
# See http://scrapy.readthedocs.org/en/latest/topics/settings.html#download-delay
# See also autothrottle settings and docs
#DOWNLOAD_DELAY = 3
# The download delay setting will honor only one of:
 

• 設置對每個網站和每個IP的最大並發請求數量，兩個最好只設置一個，如果都設置，則按照限制IP生效。

#CONCURRENT_REQUESTS_PER_DOMAIN = 16
#CONCURRENT_REQUESTS_PER_IP = 16

• 設置是否禁用cookie，目前默認是可用的，去掉註釋則禁用

# Disable cookies (enabled by default)
#COOKIES_ENABLED = False

• 設置是否可遠程登錄控制臺，目前默認是可以的，去掉註釋則禁用

# Disable Telnet Console (enabled by default)
#TELNETCONSOLE_ENABLED = False

• 用來設置請求頭，一般不用，因為請求頭可以動態設置

# Override the default request headers:
#DEFAULT_REQUEST_HEADERS = {
#   ‘Accept‘: ‘text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8‘,
#   ‘Accept-Language‘: ‘en‘,
#}

• 是否開啟使用爬蟲spider的中間件,默認不啟用，解除註釋後啟用，後面的數字代表優先級，數字越小，優先級越高

# Enable or disable spider middlewares
# See http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html
#SPIDER_MIDDLEWARES = {
#    ‘new_center.middlewares.NewCenterSpiderMiddleware‘: 543,
#}

• 是否開啟爬蟲下載器的中間件,默認不啟用，解除註釋後啟用

# Enable or disable downloader middlewares
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {
#    ‘new_center.middlewares.MyCustomDownloaderMiddleware‘: 543,
#}

• 是否禁用爬蟲擴展，默認禁用，解除註釋後將None改成數字，如500，擴展的優先級一般不重要，因為他們並不相互依賴，多個擴展的value值可以寫相同。

# Enable or disable extensions
# See http://scrapy.readthedocs.org/en/latest/topics/extensions.html
#EXTENSIONS = {
#    ‘scrapy.extensions.telnet.TelnetConsole‘: None,
#}

• 是否開啟管道，默認關閉，開啟則解除註釋

# Configure item pipelines
# See http://scrapy.readthedocs.org/en/latest/topics/item-pipeline.html
#ITEM_PIPELINES = {
#    ‘new_center.pipelines.NewCenterPipeline‘: 300,
#}

• 設置自動限速，根據Scrapy服務器及爬取的網站的負載自動限制爬取速度，默認關閉，開啟需解除註釋。

# Enable and configure the AutoThrottle extension (disabled by default)
# See http://doc.scrapy.org/en/latest/topics/autothrottle.html
#AUTOTHROTTLE_ENABLED = True  # 自動限速的開關
# The initial download delay  
#AUTOTHROTTLE_START_DELAY = 5  # 初始下載延時
# The maximum download delay to be set in case of high latencies
#AUTOTHROTTLE_MAX_DELAY = 60  # 最大下載延時
# The average number of requests Scrapy should be sending in parallel to
# each remote server
#AUTOTHROTTLE_TARGET_CONCURRENCY = 1.0
# Enable showing throttling stats for every response received:
#AUTOTHROTTLE_DEBUG = False

• 啟用和配置HTTP緩存

# Enable and configure HTTP caching (disabled by default)
# 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‘

scrapy爬蟲框架setting模塊解析