Scrapy—settings设置

最新推荐文章于 2025-05-03 16:49:00 发布

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这篇博客详细介绍了Scrapy爬虫框架的设置，包括爬虫名称、客户端user-agent、并发请求、下载延迟、请求头、item pipelines、自定义扩展、深度限制、调度器队列、URL去重、自动限速和HTTP缓存策略等关键配置选项。

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-- coding: utf-8 --

Scrapy settings for step8_king 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

1. 爬虫名称

BOT_NAME = ‘step8_king’

2. 爬虫应用路径

SPIDER_MODULES = [‘step8_king.spiders’]
NEWSPIDER_MODULE = ‘step8_king.spiders’

Crawl responsibly by identifying yourself (and your website) on the user-agent

3. 客户端 user-agent请求头

USER_AGENT = ‘step8_king (+http://www.yourdomain.com)’

Obey robots.txt rules

4. 禁止爬虫配置

ROBOTSTXT_OBEY = False

Configure maximum concurrent requests performed by Scrapy (default: 16)

5. 并发请求数

CONCURRENT_REQUESTS = 4

Configure a delay for requests for the same website (default: 0)

See http://scrapy.readthedocs.org/en/latest/topics/settings.html#download-delay

6. 延迟下载秒数

DOWNLOAD_DELAY = 2

The download delay setting will honor only one of:

7. 单域名访问并发数，并且延迟下次秒数也应用在每个域名

CONCURRENT_REQUESTS_PER_DOMAIN = 2

单IP访问并发数，如果有值则忽略：CONCURRENT_REQUESTS_PER_DOMAIN，并且延迟下次秒数也应用在每个IP

CONCURRENT_REQUESTS_PER_IP = 3

Disable cookies (enabled by default)

8. 是否支持cookie，cookiejar进行操作cookie

COOKIES_ENABLED = True

COOKIES_DEBUG = True

Disable Telnet Console (enabled by default)

9. Telnet用于查看当前爬虫的信息，操作爬虫等…

使用telnet ip port ，然后通过命令操作

TELNETCONSOLE_ENABLED = True

TELNETCONSOLE_HOST = ‘127.0.0.1’

TELNETCONSOLE_PORT = [6023,]

10. 默认请求头

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’,

}

Configure item pipelines

See http://scrapy.readthedocs.org/en/latest/topics/item-pipeline.html

11. 定义pipeline处理请求

ITEM_PIPELINES = {

‘step8_king.pipelines.JsonPipeline’: 700,

‘step8_king.pipelines.FilePipeline’: 500,

}

12. 自定义扩展，基于信号进行调用

Enable or disable extensions

See http://scrapy.readthedocs.org/en/latest/topics/extensions.html

EXTENSIONS = {

# ‘step8_king.extensions.MyExtension’: 500,

}

13. 爬虫允许的最大深度，可以通过meta查看当前深度；0表示无深度

DEPTH_LIMIT = 3

14. 爬取时，0表示深度优先Lifo(默认)；1表示广度优先FiFo

后进先出，深度优先

DEPTH_PRIORITY = 0

SCHEDULER_DISK_QUEUE = ‘scrapy.squeue.PickleLifoDiskQueue’

SCHEDULER_MEMORY_QUEUE = ‘scrapy.squeue.LifoMemoryQueue’

先进先出，广度优先

DEPTH_PRIORITY = 1

SCHEDULER_DISK_QUEUE = ‘scrapy.squeue.PickleFifoDiskQueue’

SCHEDULER_MEMORY_QUEUE = ‘scrapy.squeue.FifoMemoryQueue’

15. 调度器队列

SCHEDULER = ‘scrapy.core.scheduler.Scheduler’

from scrapy.core.scheduler import Scheduler

16. 访问URL去重

DUPEFILTER_CLASS = ‘step8_king.duplication.RepeatUrl’

Enable and configure the AutoThrottle extension (disabled by default)

See http://doc.scrapy.org/en/latest/topics/autothrottle.html

“”"
17. 自动限速算法
from scrapy.contrib.throttle import AutoThrottle
自动限速设置
1. 获取最小延迟 DOWNLOAD_DELAY 默认 5.0
2. 获取最大延迟 AUTOTHROTTLE_MAX_DELAY 默认60
3. 设置初始下载延迟 AUTOTHROTTLE_START_DELAY
4. 当请求下载完成后，获取其"连接"时间 latency，即：请求连接到接受到响应头之间的时间
5. 用于计算的… AUTOTHROTTLE_TARGET_CONCURRENCY
target_delay = latency / self.target_concurrency
new_delay = (slot.delay + target_delay) / 2.0 # 表示上一次的延迟时间
new_delay = max(target_delay, new_delay)
new_delay = min(max(self.mindelay, new_delay), self.maxdelay)
slot.delay = new_delay
“”"

开始自动限速

AUTOTHROTTLE_ENABLED = True

The initial download delay

初始下载延迟

AUTOTHROTTLE_START_DELAY = 5

The maximum download delay to be set in case of high latencies

最大下载延迟

AUTOTHROTTLE_MAX_DELAY = 10

The average number of requests Scrapy should be sending in parallel to each remote server

平均每秒并发数

AUTOTHROTTLE_TARGET_CONCURRENCY = 1.0

Enable showing throttling stats for every response received:

是否显示

AUTOTHROTTLE_DEBUG = True

起用AutoThrottle调试(debug)模式，展示每个接收到的response。您可以通过此来查看限速参数是如何实时被调整的。

Enable and configure HTTP caching (disabled by default)

See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html#httpcache-middleware-settings

“”"
18. 启用缓存
目的用于将已经发送的请求或相应缓存下来，以便以后使用

from scrapy.downloadermiddlewares.httpcache import HttpCacheMiddleware
from scrapy.extensions.httpcache import DummyPolicy
from scrapy.extensions.httpcache import FilesystemCacheStorage

“”"

是否启用缓存策略

HTTPCACHE_ENABLED = True

缓存策略：所有请求均缓存，下次在请求直接访问原来的缓存即可

HTTPCACHE_POLICY = “scrapy.extensions.httpcache.DummyPolicy”

缓存策略：根据Http响应头：Cache-Control、Last-Modified 等进行缓存的策略

HTTPCACHE_POLICY = “scrapy.extensions.httpcache.RFC2616Policy”

缓存超时时间

HTTPCACHE_EXPIRATION_SECS = 0

缓存保存路径

HTTPCACHE_DIR = ‘httpcache’

缓存忽略的Http状态码

HTTPCACHE_IGNORE_HTTP_CODES = []

缓存存储的插件

HTTPCACHE_STORAGE = ‘scrapy.extensions.httpcache.FilesystemCacheStorage’

“”"
19. 代理，需要在环境变量中设置
from scrapy.contrib.downloadermiddleware.httpproxy import HttpProxyMiddleware

方式一：使用默认
    os.environ
    {
        http_proxy:http://root:woshiniba@192.168.11.11:9999/
        https_proxy:http://192.168.11.11:9999/
    }
方式二：使用自定义下载中间件

def to_bytes(text, encoding=None, errors='strict'):
    if isinstance(text, bytes):
        return text
    if not isinstance(text, six.string_types):
        raise TypeError('to_bytes must receive a unicode, str or bytes '
                        'object, got %s' % type(text).__name__)
    if encoding is None:
        encoding = 'utf-8'
    return text.encode(encoding, errors)
    
class ProxyMiddleware(object):
    def process_request(self, request, spider):
        PROXIES = [
            {'ip_port': '111.11.228.75:80', 'user_pass': ''},
            {'ip_port': '120.198.243.22:80', 'user_pass': ''},
            {'ip_port': '111.8.60.9:8123', 'user_pass': ''},
            {'ip_port': '101.71.27.120:80', 'user_pass': ''},
            {'ip_port': '122.96.59.104:80', 'user_pass': ''},
            {'ip_port': '122.224.249.122:8088', 'user_pass': ''},
        ]
        proxy = random.choice(PROXIES)
        if proxy['user_pass'] is not None:
            request.meta['proxy'] = to_bytes（"http://%s" % proxy['ip_port']）
            encoded_user_pass = base64.encodestring(to_bytes(proxy['user_pass']))
            request.headers['Proxy-Authorization'] = to_bytes('Basic ' + encoded_user_pass)
            print "**************ProxyMiddleware have pass************" + proxy['ip_port']
        else:
            print "**************ProxyMiddleware no pass************" + proxy['ip_port']
            request.meta['proxy'] = to_bytes("http://%s" % proxy['ip_port'])

DOWNLOADER_MIDDLEWARES = {
   'step8_king.middlewares.ProxyMiddleware': 500,
}

“”"

“”"
20. Https访问
Https访问时有两种情况：
1. 要爬取网站使用的可信任证书(默认支持)
DOWNLOADER_HTTPCLIENTFACTORY = “scrapy.core.downloader.webclient.ScrapyHTTPClientFactory”
DOWNLOADER_CLIENTCONTEXTFACTORY = “scrapy.core.downloader.contextfactory.ScrapyClientContextFactory”

2. 要爬取网站使用的自定义证书
    DOWNLOADER_HTTPCLIENTFACTORY = "scrapy.core.downloader.webclient.ScrapyHTTPClientFactory"
    DOWNLOADER_CLIENTCONTEXTFACTORY = "step8_king.https.MySSLFactory"
    
    # https.py
    from scrapy.core.downloader.contextfactory import ScrapyClientContextFactory
    from twisted.internet.ssl import (optionsForClientTLS, CertificateOptions, PrivateCertificate)
    
    class MySSLFactory(ScrapyClientContextFactory):
        def getCertificateOptions(self):
            from OpenSSL import crypto
            v1 = crypto.load_privatekey(crypto.FILETYPE_PEM, open('/Users/wupeiqi/client.key.unsecure', mode='r').read())
            v2 = crypto.load_certificate(crypto.FILETYPE_PEM, open('/Users/wupeiqi/client.pem', mode='r').read())
            return CertificateOptions(
                privateKey=v1,  # pKey对象
                certificate=v2,  # X509对象
                verify=False,
                method=getattr(self, 'method', getattr(self, '_ssl_method', None))
            )
其他：
    相关类
        scrapy.core.downloader.handlers.http.HttpDownloadHandler
        scrapy.core.downloader.webclient.ScrapyHTTPClientFactory
        scrapy.core.downloader.contextfactory.ScrapyClientContextFactory
    相关配置
        DOWNLOADER_HTTPCLIENTFACTORY
        DOWNLOADER_CLIENTCONTEXTFACTORY

“”"

“”"
21. 爬虫中间件
class SpiderMiddleware(object):

    def process_spider_input(self,response, spider):
        '''
        下载完成，执行，然后交给parse处理
        :param response: 
        :param spider: 
        :return: 
        '''
        pass

    def process_spider_output(self,response, result, spider):
        '''
        spider处理完成，返回时调用
        :param response:
        :param result:
        :param spider:
        :return: 必须返回包含 Request 或 Item 对象的可迭代对象(iterable)
        '''
        return result

    def process_spider_exception(self,response, exception, spider):
        '''
        异常调用
        :param response:
        :param exception:
        :param spider:
        :return: None,继续交给后续中间件处理异常；含 Response 或 Item 的可迭代对象(iterable)，交给调度器或pipeline
        '''
        return None


    def process_start_requests(self,start_requests, spider):
        '''
        爬虫启动时调用
        :param start_requests:
        :param spider:
        :return: 包含 Request 对象的可迭代对象
        '''
        return start_requests

内置爬虫中间件：
    'scrapy.contrib.spidermiddleware.httperror.HttpErrorMiddleware': 50,
    'scrapy.contrib.spidermiddleware.offsite.OffsiteMiddleware': 500,
    'scrapy.contrib.spidermiddleware.referer.RefererMiddleware': 700,
    'scrapy.contrib.spidermiddleware.urllength.UrlLengthMiddleware': 800,
    'scrapy.contrib.spidermiddleware.depth.DepthMiddleware': 900,

“”"

from scrapy.contrib.spidermiddleware.referer import RefererMiddleware

Enable or disable spider middlewares

See http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html

SPIDER_MIDDLEWARES = {

‘step8_king.middlewares.SpiderMiddleware’: 543,

}

“”"
22. 下载中间件
class DownMiddleware1(object):
def process_request(self, request, spider):
‘’’
请求需要被下载时，经过所有下载器中间件的process_request调用
:param request:
:param spider:
:return:
None,继续后续中间件去下载；
Response对象，停止process_request的执行，开始执行process_response
Request对象，停止中间件的执行，将Request重新调度器
raise IgnoreRequest异常，停止process_request的执行，开始执行process_exception
‘’’
pass

    def process_response(self, request, response, spider):
        '''
        spider处理完成，返回时调用
        :param response:
        :param result:
        :param spider:
        :return:
            Response 对象：转交给其他中间件process_response
            Request 对象：停止中间件，request会被重新调度下载
            raise IgnoreRequest 异常：调用Request.errback
        '''
        print('response1')
        return response

    def process_exception(self, request, exception, spider):
        '''
        当下载处理器(download handler)或 process_request() (下载中间件)抛出异常
        :param response:
        :param exception:
        :param spider:
        :return:
            None：继续交给后续中间件处理异常；
            Response对象：停止后续process_exception方法
            Request对象：停止中间件，request将会被重新调用下载
        '''
        return None



默认下载中间件
{
    'scrapy.contrib.downloadermiddleware.robotstxt.RobotsTxtMiddleware': 100,
    'scrapy.contrib.downloadermiddleware.httpauth.HttpAuthMiddleware': 300,
    'scrapy.contrib.downloadermiddleware.downloadtimeout.DownloadTimeoutMiddleware': 350,
    'scrapy.contrib.downloadermiddleware.useragent.UserAgentMiddleware': 400,
    'scrapy.contrib.downloadermiddleware.retry.RetryMiddleware': 500,
    'scrapy.contrib.downloadermiddleware.defaultheaders.DefaultHeadersMiddleware': 550,
    'scrapy.contrib.downloadermiddleware.redirect.MetaRefreshMiddleware': 580,
    'scrapy.contrib.downloadermiddleware.httpcompression.HttpCompressionMiddleware': 590,
    'scrapy.contrib.downloadermiddleware.redirect.RedirectMiddleware': 600,
    'scrapy.contrib.downloadermiddleware.cookies.CookiesMiddleware': 700,
    'scrapy.contrib.downloadermiddleware.httpproxy.HttpProxyMiddleware': 750,
    'scrapy.contrib.downloadermiddleware.chunked.ChunkedTransferMiddleware': 830,
    'scrapy.contrib.downloadermiddleware.stats.DownloaderStats': 850,
    'scrapy.contrib.downloadermiddleware.httpcache.HttpCacheMiddleware': 900,
}