V2AS问路
Scrapy进阶
阅读原文时间：2021年08月03日阅读：1

当我们使用scrapy框架爬取网站的时候，我们会有一个入口的url，一个名为start_urls,我们爬取的第一个网页是从这一开始的。

　　现在我们有一个这样的需求，比如说我们对起始的URL有一个相对应的处理函数，对后面的爬取的url又要进行一个新的处理那么我们需要两个处理函数。

　　如果我们想对起始的url的处理函数不为默认的parser那我们应该怎么修改呢

在父类的中我们可以看到一个名为start_requests的函数他就控制了起始url使用什么调用什么回调函数所以我们只要重写他就可以了，在scrapy中yield一个Request对象（已经可以设置callback了）

那么scrapy框架会自动将其放入调度器，然后爬取

class ZhipinSpider(scrapy.Spider):
name = 'zhipin'
allowed_domains = ['zhipin.com']
start_urls = ['xxx.com']

# 方案一  
def start\_requests(self):  
        for url in self.start\_urls:  
            yield Request(url=url,callback=self.parse2)

# 方案二  
def start\_requests(self):  
req\_list = \[\]  
for url in self.start\_urls:  
    req\_list.append(Request(url=url,callback=self.parse2))  
return req\_list

def parser(self, response):  
    pass

def parser2(self, response):  
    pass

这里使用yield和返回一个列表的效果是一样的，因为在scrapy内部会使用iter()方法最后返回的都是一个可迭代对象。

parser中的参数是一个response对象我们需要用解析器来对其进行解析

有两种方式一种是他内部实现了我们可以直接对其进行解析

response.xpath('//div[@id='content-list']/div[@class='item']')

还有一种是导入模块的方式进行解析：

from scrapy.selector import HtmlXPathSelector

。。。
def parser(self, response):
hxs = HtmlXPathSelector(respone=response)
items = hxs.xpath("//div[@id='content-list']/div[@class='item']")

查找规则：

hxs = Selector(response=response).xpath('//div') # 去子子孙孙下找div标签

hxs = Selector(response=response).xpath('/div') # 去儿子下找div 标签

hxs = Selector(response=response).xpath('//div[2]') # 去子子孙孙下找第二个div标签

hxs = Selector(response=response).xpath('//a[@id]') # 找有id属性的a标签

hxs = Selector(response=response).xpath('//a[@id="i1"]') # 找id="i1"的所有a标签（id不重复，但是可能不是id的情况下）

hxs = Selector(response=response).xpath('//a[@href="link.html"][@id="i1"]') # 且的关系

hxs = Selector(response=response).xpath('//a[contains(@href, "link")]') # 有这两个属性的a标签

hxs = Selector(response=response).xpath('//a[re:test(@id, "i\d+")]') # 使用正则来匹配

解析得到的类型：

标签对象： xpath('/html/body/ul/li/a/@href')
列表： xpath('/html/body/ul/li/a/@href').extract()
值： xpath('//body/ul/li/a/@href').extract_first()

如何独立使用scrapy的解析器：

from scrapy.selector import Selector, HtmlXPathSelector
from scrapy.http import HtmlResponse
html = """


"""
response = HtmlResponse(url='http://example.com', body=html,encoding='utf-8')
obj = response.xpath('//a[@id="i1"]/text()').extract_first()
print(obj)

单独应用

上述实例只是简单的处理，所以在parse方法中直接处理。如果对于想要获取更多的数据处理，则可以利用Scrapy的items将数据格式化，然后统一交由pipelines来处理。

当yield一个item对象时会直接去pipeline中执行持久化操作

import scrapy
from scrapy.selector import HtmlXPathSelector
from scrapy.http.request import Request
from scrapy.http.cookies import CookieJar
from scrapy import FormRequest

class XiaoHuarSpider(scrapy.Spider):
# 爬虫应用的名称，通过此名称启动爬虫命令
name = "xiaohuar"
# 允许的域名
allowed_domains = ["xiaohuar.com"]

start\_urls = \[  
    "http://www.xiaohuar.com/list-1-1.html",  
\]  
# custom\_settings = {  
#     'ITEM\_PIPELINES':{  
#         'spider1.pipelines.JsonPipeline': 100  
#     }  
# }  
has\_request\_set = {}

def parse(self, response):  
    # 分析页面  
    # 找到页面中符合规则的内容（校花图片），保存  
    # 找到所有的a标签，再访问其他a标签，一层一层的搞下去

    hxs = HtmlXPathSelector(response)

    items = hxs.select('//div\[@class="item\_list infinite\_scroll"\]/div')  
    for item in items:  
        src = item.select('.//div\[@class="img"\]/a/img/@src').extract\_first()  
        name = item.select('.//div\[@class="img"\]/span/text()').extract\_first()  
        school = item.select('.//div\[@class="img"\]/div\[@class="btns"\]/a/text()').extract\_first()  
        url = "http://www.xiaohuar.com%s" % src  
        from ..items import XiaoHuarItem  
        obj = XiaoHuarItem(name=name, school=school, url=url)  
        yield obj

    urls = hxs.select('//a\[re:test(@href, "http://www.xiaohuar.com/list-1-\\d+.html")\]/@href')  
    for url in urls:  
        key = self.md5(url)  
        if key in self.has\_request\_set:  
            pass  
        else:  
            self.has\_request\_set\[key\] = url  
            req = Request(url=url,method='GET',callback=self.parse)  
            yield req

@staticmethod  
def md5(val):  
    import hashlib  
    ha = hashlib.md5()  
    ha.update(bytes(val, encoding='utf-8'))  
    key = ha.hexdigest()  
    return key

spider.py

import scrapy

class XiaoHuarItem(scrapy.Item):
name = scrapy.Field()
school = scrapy.Field()
url = scrapy.Field()

items.py

import json
import os
import requests

class JsonPipeline(object):
def __init__(self):
self.file = open('xiaohua.txt', 'w')

def process\_item(self, item, spider):  
    v = json.dumps(dict(item), ensure\_ascii=False)  
    self.file.write(v)  
    self.file.write('\\n')  
    self.file.flush()  
    return item

class FilePipeline(object):
def __init__(self):
if not os.path.exists('imgs'):
os.makedirs('imgs')

def process\_item(self, item, spider):  
    response = requests.get(item\['url'\], stream=True)  
    file\_name = '%s\_%s.jpg' % (item\['name'\], item\['school'\])  
    with open(os.path.join('imgs', file\_name), mode='wb') as f:  
        f.write(response.content)  
    return item

pipeline

ITEM_PIPELINES = {
'spider1.pipelines.JsonPipeline': 100,
'spider1.pipelines.FilePipeline': 300,
}

每行后面的整型值，确定了他们运行的顺序，item按数字从低到高的顺序，通过pipeline，通常将这些数字定义在0-1000范围内。

pipeline更多的方法

from scrapy.exceptions import DropItem

class CustomPipeline(object):
def __init__(self,v):
self.value = v

def process\_item(self, item, spider):  
    # 操作并进行持久化

    # return表示会被后续的pipeline继续处理  
    return item

    # 表示将item丢弃，不会被后续pipeline处理  
    # raise DropItem()

@classmethod  
def from\_crawler(cls, crawler):  
    """  
    初始化时候，用于创建pipeline对象  
    :param crawler:  
    :return:  
    """  
    val = crawler.settings.getint('MMMM')  
    return cls(val)

def open\_spider(self,spider):  
    """  
    爬虫开始执行时，调用  
    :param spider:  
    :return:  
    """  
    print('')

def close\_spider(self,spider):  
    """  
    爬虫关闭时，被调用  
    :param spider:  
    :return:  
    """  
    print('')

more_pipeline

要在settings文件中配置相应的类

DUPEFILTER_CLASS = 'scrapy.dupefilter.RFPDupeFilter'
DUPEFILTER_DEBUG = False
JOBDIR = "保存范文记录的日志路径，如：/root/" # 最终路径为 /root/requests.seen

自定义：

class RepeatUrl:
def __init__(self):
self.visited_url = set()

@classmethod  
def from\_settings(cls, settings):  
    """  
    初始化时，调用  
    :param settings:  
    :return:  
    """  
    return cls()

def request\_seen(self, request):  
    """  
    检测当前请求是否已经被访问过  
    :param request:  
    :return: True表示已经访问过；False表示未访问过  
    """  
    if request.url in self.visited\_url:  
        return True  
    self.visited\_url.add(request.url)  
    return False

def open(self):  
    """  
    开始爬去请求时，调用  
    :return:  
    """  
    print('open replication')

def close(self, reason):  
    """  
    结束爬虫爬取时，调用  
    :param reason:  
    :return:  
    """  
    print('close replication')

def log(self, request, spider):  
    """  
    记录日志  
    :param request:  
    :param spider:  
    :return:  
    """  
    print('repeat', request.url)

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

爬虫中间件

爬虫中间件

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

下载器中间件

下载中间件

  • 在spiders同级创建任意目录，如：commands
  • 在其中创建 crawlall.py 文件 （此处文件名就是自定义的命令）

如果想运行所有的爬虫：

from scrapy.commands import ScrapyCommand
from scrapy.utils.project import get_project_settings

class Command(ScrapyCommand):

    requires\_project = True

    def syntax(self):  
        return '\[options\]'

    def short\_desc(self):  
        return 'Runs all of the spiders'

    def run(self, args, opts):  
        spider\_list = self.crawler\_process.spiders.list()  
        for name in spider\_list:  
            self.crawler\_process.crawl(name, \*\*opts.\_\_dict\_\_)  
        self.crawler\_process.start()

crawlall.py

  • 在settings.py 中添加配置 COMMANDS_MODULE = '项目名称.目录名称'
  • 在项目目录执行命令：scrapy crawlall

# -*- 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

See also autothrottle settings and docs

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

"""

  1. 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
    2. 获取最大延迟 AUTOTHROTTLE_MAX_DELAY
    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

Enable and configure HTTP caching (disabled by default)

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

"""

  1. 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'

"""

  1. 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,
    }

"""

"""

  1. 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

"""

"""

  1. 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,
}

"""

  1. 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,
    }

"""

from scrapy.contrib.downloadermiddleware.httpauth import HttpAuthMiddleware

Enable or disable downloader middlewares

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

DOWNLOADER_MIDDLEWARES = {

'step8_king.middlewares.DownMiddleware1': 100,

'step8_king.middlewares.DownMiddleware2': 500,

}

settings

settings

手机扫一扫

移动阅读更方便

阿里云服务器
腾讯云服务器
七牛云服务器

你可能感兴趣的文章

Python：Scrapy（一） 基础知识与实例
python用scrapy模拟用户登录
Python爬虫之Scrapy框架爬虫实战

4

python的scrapy框架的使用 和xpath的使用 && scrapy中request和response的函数参数 && parse()函数运行机制

5

爬虫入门六 总结 资料 与Scrapy实例-bibibili番剧信息

6

爬虫系列之Scrapy框架

7

1. scrapy 框架应该怎么学习(前言)

8

Centos7__Scrapy + Scrapy_redis 用Docker 实现分布式爬虫

9

如何优雅的在scrapy中使用selenium —— 在scrapy中实现浏览器池

10

python-scrapy框架学习