scrapy基础

性能相关

在编写爬虫时，性能的消耗主要在IO请求中，当单进程单线程模式下请求URL时必然会引起等待，从而使得请求整体变慢。

同步执行
import requests

def fetch_async(url):
response = requests.get(url)
return response

url_list = ['http://www.github.com', 'http://www.bing.com']

for url in url_list:
fetch_async(url)

多线程执行

from concurrent.futures import ThreadPoolExecutor
import requests

def fetch_async(url):
response = requests.get(url)
return response

url_list = ['http://www.github.com', 'http://www.bing.com']
pool = ThreadPoolExecutor(5)
for url in url_list:
pool.submit(fetch_async, url)
pool.shutdown(wait=True)

多线程+回调函数执行

from concurrent.futures import ThreadPoolExecutor
import requests

def fetch_async(url):
response = requests.get(url)
return response

def callback(future):
print(future.result())

url_list = ['http://www.github.com', 'http://www.bing.com']
pool = ThreadPoolExecutor(5)
for url in url_list:
v = pool.submit(fetch_async, url)
v.add_done_callback(callback)
pool.shutdown(wait=True)

多进程执行

from concurrent.futures import ProcessPoolExecutor
import requests

def fetch_async(url):
response = requests.get(url)
return response

url_list = ['http://www.github.com', 'http://www.bing.com']
pool = ProcessPoolExecutor(5)
for url in url_list:
pool.submit(fetch_async, url)
pool.shutdown(wait=True)

多进程+回调函数执行

from concurrent.futures import ProcessPoolExecutor
import requests

def fetch_async(url):
response = requests.get(url)
return response

def callback(future):
print(future.result())

url_list = ['http://www.github.com', 'http://www.bing.com']
pool = ProcessPoolExecutor(5)
for url in url_list:
v = pool.submit(fetch_async, url)
v.add_done_callback(callback)
pool.shutdown(wait=True)

通过上述代码均可以完成对请求性能的提高，对于多线程和多进行的缺点是在IO阻塞时会造成了线程和进程的浪费，所以异步IO会是首选，异步IO请求的本质则是【非阻塞Socket】+【IO多路复用】。

Scrapy

Scrapy是一个为了爬取网站数据，提取结构性数据而编写的应用框架。其可以应用在数据挖掘，信息处理或存储历史数据等一系列的程序中。
其最初是为了页面抓取 (更确切来说, 网络抓取 )所设计的，也可以应用在获取API所返回的数据(例如 Amazon Associates Web Services ) 或者通用的网络爬虫。Scrapy用途广泛，可以用于数据挖掘、监测和自动化测试。

Scrapy 使用了 Twisted异步网络库来处理网络通讯。整体架构大致如下：

Scrapy主要包括了以下组件：

引擎(Scrapy)
用来处理整个系统的数据流处理, 触发事务(框架核心)
调度器(Scheduler)
用来接受引擎发过来的请求, 压入队列中, 并在引擎再次请求的时候返回. 可以想像成一个URL（抓取网页的网址或者说是链接）的优先队列, 由它来决定下一个要抓取的网址是什么, 同时去除重复的网址。
下载器(Downloader)
用于下载网页内容, 并将网页内容返回给蜘蛛(Scrapy下载器是建立在twisted这个高效的异步模型上的)
爬虫(Spiders)
爬虫是主要干活的, 用于从特定的网页中提取自己需要的信息, 即所谓的实体(Item)。用户也可以从中提取出链接,让Scrapy继续抓取下一个页面
项目管道(Pipeline)
负责处理爬虫从网页中抽取的实体，主要的功能是持久化实体、验证实体的有效性、清除不需要的信息。当页面被爬虫解析后，将被发送到项目管道，并经过几个特定的次序处理数据。
下载器中间件(Downloader Middlewares)
位于Scrapy引擎和下载器之间的框架，主要是处理Scrapy引擎与下载器之间的请求及响应。
爬虫中间件(Spider Middlewares)
介于Scrapy引擎和爬虫之间的框架，主要工作是处理蜘蛛的响应输入和请求输出。
调度中间件(Scheduler Middewares)
介于Scrapy引擎和调度之间的中间件，从Scrapy引擎发送到调度的请求和响应。

Scrapy运行流程大概如下：

引擎从调度器中取出一个链接(URL)用于接下来的抓取
引擎把URL封装成一个请求(Request)传给下载器
下载器把资源下载下来，并封装成应答包(Response)
爬虫解析Response
解析出实体（Item）,则交给实体管道进行进一步的处理
解析出的是链接（URL）,则把URL交给调度器等待抓取

一、安装

Linux
pip3 install scrapy

Windows
a. pip3 install wheel
b. 下载twisted http://www.lfd.uci.edu/~gohlke/pythonlibs/#twisted
c. 进入下载目录，执行 pip3 install Twisted‑17.1.0‑cp35‑cp35m‑win_amd64.whl
d. pip3 install scrapy
e. 下载并安装pywin32：https://sourceforge.net/projects/pywin32/files/

二、基本使用

基本命令
1. scrapy startproject 项目名称
  - 在当前目录中创建中创建一个项目文件（类似于Django）
2. scrapy genspider [-t template]
  - 创建爬虫应用
    如：
    scrapy gensipider -t basic oldboy oldboy.com
    scrapy gensipider -t xmlfeed autohome autohome.com.cn
    PS:
    查看所有命令：scrapy gensipider -l
    查看模板命令：scrapy gensipider -d 模板名称
3. scrapy list
  - 展示爬虫应用列表
4. scrapy crawl 爬虫应用名称
  - 运行单独爬虫应用

2.项目结构以及爬虫应用简介

project_name/
scrapy.cfg
project_name/
init.py
items.py
pipelines.py
settings.py
spiders/
init.py
爬虫1.py
爬虫2.py
爬虫3.py
文件说明：

scrapy.cfg 项目的主配置信息。（真正爬虫相关的配置信息在settings.py文件中）
items.py 设置数据存储模板，用于结构化数据，如：Django的Model
pipelines 数据处理行为，如：一般结构化的数据持久化
settings.py 配置文件，如：递归的层数、并发数，延迟下载等
spiders 爬虫目录，如：创建文件，编写爬虫规则

注意：一般创建爬虫文件时，以网站域名命名。如：scrapy genspider baidu baidu.com

import scrapy

class XiaoHuarSpider(scrapy.spiders.Spider):
name = "xiaohuar" # 爬虫名称 *****
allowed_domains = ["xiaohuar.com"] # 允许的域名
start_urls = [
"http://www.xiaohuar.com/hua/", # 其实URL
]

def parse(self, response):
# 访问起始URL并获取结果后的回调函数

windows 编码

import sys,os
sys.stdout=io.TextIOWrapper(sys.stdout.buffer,encoding='gb18030')

3.小试牛刀

import scrapy
from scrapy.selector import HtmlXPathSelector
from scrapy.http.request import Request

class DigSpider(scrapy.Spider):
# 爬虫应用的名称，通过此名称启动爬虫命令
name = "dig"

允许的域名

allowed_domains = ["chouti.com"]

起始URL

start_urls = [
'http://dig.chouti.com/',
]

has_request_set = {}

def parse(self, response):
print(response.url)

hxs = HtmlXPathSelector(response)
page_list = hxs.select('//div[@id="dig_lcpage"]//a[re:test(@href, "/all/hot/recent/\d+")]/@href').extract()
for page in page_list:
page_url = 'http://dig.chouti.com%s' % page
key = self.md5(page_url)
if key in self.has_request_set:
pass
else:
self.has_request_set[key] = page_url
obj = Request(url=page_url, method='GET', callback=self.parse)
yield obj

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

执行此爬虫文件，则在终端进入项目目录执行如下命令：

scrapy crawl dig --nolog

对于上述代码重要之处在于：

Request是一个封装用户请求的类，在回调函数中yield该对象表示继续访问
HtmlXpathSelector用于结构化HTML代码并提供选择器功能

4.选择器

!/usr/bin/env python

-- coding:utf-8 --

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

first item

first item

second itemvv

second item

"""
response = HtmlResponse(url='http://example.com', body=html,encoding='utf-8')
# hxs = HtmlXPathSelector(response)
# print(hxs)
# hxs = Selector(response=response).xpath('//a')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[2]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[@id]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[@id="i1"]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[@href="link.html"][@id="i1"]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[contains(@href, "link")]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[starts-with(@href, "link")]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[re:test(@id, "i\d+")]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[re:test(@id, "i\d+")]/text()').extract()
# print(hxs)
# hxs = Selector(response=response).xpath('//a[re:test(@id, "i\d+")]/@href').extract()
# print(hxs)
# hxs = Selector(response=response).xpath('/html/body/ul/li/a/@href').extract()
# print(hxs)
# hxs = Selector(response=response).xpath('//body/ul/li/a/@href').extract_first()
# print(hxs)

ul_list = Selector(response=response).xpath('//body/ul/li')

for item in ul_list:

v = item.xpath('./a/span')

# 或

# v = item.xpath('a/span')

# 或

# v = item.xpath('*/a/span')

print(v)

5.格式化处理

xiaohua.py

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

items(将获取的信息如何保存相当于model)

import scrapy

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

pipeline（保存在json，数据库或是文件中）

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

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。

对于pipeline可以做更多，如下：

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('000000')

def close_spider(self,spider):
"""
爬虫关闭时，被调用
:param spider:
:return:
"""
print('111111')

6.中间件

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

下载器中间件

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

7.自定制命令

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）

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()

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

8. 自定义扩展

自定义扩展时，利用信号在指定位置注册制定操作

from scrapy import signals

class MyExtension(object):
def init(self, value):
self.value = value

@classmethod
def from_crawler(cls, crawler):
val = crawler.settings.getint('MMMM')
ext = cls(val)

crawler.signals.connect(ext.spider_opened, signal=signals.spider_opened)
crawler.signals.connect(ext.spider_closed, signal=signals.spider_closed)

return ext

def spider_opened(self, spider):
print('open')

def spider_closed(self, spider):
print('close')

配置文件中开启自定义的扩展

EXTENSIONS = {

# 'scrapy.extensions.telnet.TelnetConsole': None,

'scrapy01.extensions.MyExtend': 300,

}

9. 避免重复访问

scrapy默认使用 scrapy.dupefilter.RFPDupeFilter 进行去重，相关配置有：

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

自定义去重

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)

DUPEFILTER_CLASS = 'scrapy01.duplication.RepeatUrl'

10.其他

-- 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
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

"""
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,
}

"""
# 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,
# }

py小杰

scrapy基础

性能相关

Scrapy

允许的域名

起始URL

!/usr/bin/env python

-- coding:utf-8 --

ul_list = Selector(response=response).xpath('//body/ul/li')

for item in ul_list:

v = item.xpath('./a/span')

# 或

# v = item.xpath('a/span')

# 或

# v = item.xpath('*/a/span')

print(v)

return表示会被后续的pipeline继续处理

表示将item丢弃，不会被后续pipeline处理

raise DropItem()

6.中间件

7.自定制命令

8. 自定义扩展

配置文件中开启自定义的扩展

EXTENSIONS = {

# 'scrapy.extensions.telnet.TelnetConsole': None,

'scrapy01.extensions.MyExtend': 300,

}

9. 避免重复访问

DUPEFILTER_CLASS = 'scrapy01.duplication.RepeatUrl'

10.其他

-- 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

2. 爬虫应用路径

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,