爬虫之Scrapy详解

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。

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)

1.同步执行

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)

2.多线程执行

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)

2.多线程+回调函数执行

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)

3.多进程执行

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)

3.多进程+回调函数执行

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回事首选：

import asyncio


@asyncio.coroutine
def func1():
    print(\'before...func1......\')
    yield from asyncio.sleep(5)
    print(\'end...func1......\')


tasks = [func1(), func1()]

loop = asyncio.get_event_loop()
loop.run_until_complete(asyncio.gather(*tasks))
loop.close()

1.asyncio示例1

import asyncio


@asyncio.coroutine
def fetch_async(host, url=\'/\'):
    print(host, url)
    reader, writer = yield from asyncio.open_connection(host, 80)

    request_header_content = """GET %s HTTP/1.0\r\nHost: %s\r\n\r\n""" % (url, host,)
    request_header_content = bytes(request_header_content, encoding=\'utf-8\')

    writer.write(request_header_content)
    yield from writer.drain()
    text = yield from reader.read()
    print(host, url, text)
    writer.close()

tasks = [
    fetch_async(\'www.cnblogs.com\', \'/wupeiqi/\'),
    fetch_async(\'dig.chouti.com\', \'/pic/show?nid=4073644713430508&lid=10273091\')
]

loop = asyncio.get_event_loop()
results = loop.run_until_complete(asyncio.gather(*tasks))
loop.close()

1.asyncio示例2

import aiohttp
import asyncio


@asyncio.coroutine
def fetch_async(url):
    print(url)
    response = yield from aiohttp.request(\'GET\', url)
    # data = yield from response.read()
    # print(url, data)
    print(url, response)
    response.close()


tasks = [fetch_async(\'http://www.google.com/\'), fetch_async(\'http://www.chouti.com/\')]

event_loop = asyncio.get_event_loop()
results = event_loop.run_until_complete(asyncio.gather(*tasks))
event_loop.close()

2.asyncio + aiohttp

import asyncio
import requests


@asyncio.coroutine
def fetch_async(func, *args):
    loop = asyncio.get_event_loop()
    future = loop.run_in_executor(None, func, *args)
    response = yield from future
    print(response.url, response.content)


tasks = [
    fetch_async(requests.get, \'http://www.cnblogs.com/wupeiqi/\'),
    fetch_async(requests.get, \'http://dig.chouti.com/pic/show?nid=4073644713430508&lid=10273091\')
]

loop = asyncio.get_event_loop()
results = loop.run_until_complete(asyncio.gather(*tasks))
loop.close()

3.asyncio + requests

import gevent

import requests
from gevent import monkey

monkey.patch_all()


def fetch_async(method, url, req_kwargs):
    print(method, url, req_kwargs)
    response = requests.request(method=method, url=url, **req_kwargs)
    print(response.url, response.content)

# ##### 发送请求 #####
gevent.joinall([
    gevent.spawn(fetch_async, method=\'get\', url=\'https://www.python.org/\', req_kwargs={}),
    gevent.spawn(fetch_async, method=\'get\', url=\'https://www.yahoo.com/\', req_kwargs={}),
    gevent.spawn(fetch_async, method=\'get\', url=\'https://github.com/\', req_kwargs={}),
])

# ##### 发送请求（协程池控制最大协程数量） #####
# from gevent.pool import Pool
# pool = Pool(None)
# gevent.joinall([
#     pool.spawn(fetch_async, method=\'get\', url=\'https://www.python.org/\', req_kwargs={}),
#     pool.spawn(fetch_async, method=\'get\', url=\'https://www.yahoo.com/\', req_kwargs={}),
#     pool.spawn(fetch_async, method=\'get\', url=\'https://www.github.com/\', req_kwargs={}),
# ])

4.gevent + requests

import grequests


request_list = [
    grequests.get(\'http://httpbin.org/delay/1\', timeout=0.001),
    grequests.get(\'http://fakedomain/\'),
    grequests.get(\'http://httpbin.org/status/500\')
]


# ##### 执行并获取响应列表 #####
# response_list = grequests.map(request_list)
# print(response_list)


# ##### 执行并获取响应列表（处理异常） #####
# def exception_handler(request, exception):
# print(request,exception)
#     print("Request failed")

# response_list = grequests.map(request_list, exception_handler=exception_handler)
# print(response_list)

5.grequests

from twisted.web.client import getPage, defer
from twisted.internet import reactor


def all_done(arg):
    reactor.stop()


def callback(contents):
    print(contents)


deferred_list = []

url_list = [\'http://www.bing.com\', \'http://www.baidu.com\', ]
for url in url_list:
    deferred = getPage(bytes(url, encoding=\'utf8\'))
    deferred.addCallback(callback)
    deferred_list.append(deferred)

dlist = defer.DeferredList(deferred_list)
dlist.addBoth(all_done)

reactor.run()

6.Twisted示例

from tornado.httpclient import AsyncHTTPClient
from tornado.httpclient import HTTPRequest
from tornado import ioloop


def handle_response(response):
    """
    处理返回值内容（需要维护计数器，来停止IO循环），调用 ioloop.IOLoop.current().stop()
    :param response: 
    :return: 
    """
    if response.error:
        print("Error:", response.error)
    else:
        print(response.body)


def func():
    url_list = [
        \'http://www.baidu.com\',
        \'http://www.bing.com\',
    ]
    for url in url_list:
        print(url)
        http_client = AsyncHTTPClient()
        http_client.fetch(HTTPRequest(url), handle_response)


ioloop.IOLoop.current().add_callback(func)
ioloop.IOLoop.current().start()

7.Tornado

from twisted.internet import reactor
from twisted.web.client import getPage
import urllib.parse


def one_done(arg):
    print(arg)
    reactor.stop()

post_data = urllib.parse.urlencode({\'check_data\': \'adf\'})
post_data = bytes(post_data, encoding=\'utf8\')
headers = {b\'Content-Type\': b\'application/x-www-form-urlencoded\'}
response = getPage(bytes(\'http://dig.chouti.com/login\', encoding=\'utf8\'),
                   method=bytes(\'POST\', encoding=\'utf8\'),
                   postdata=post_data,
                   cookies={},
                   headers=headers)
response.addBoth(one_done)

reactor.run()

Twisted更多

以上均是Python内置以及第三方模块提供异步IO请求模块，使用简便大大提高效率，而对于异步IO请求的本质则是【非阻塞Socket】+【IO多路复用】：

import select
import socket
import time


class AsyncTimeoutException(TimeoutError):
    """
    请求超时异常类
    """

    def __init__(self, msg):
        self.msg = msg
        super(AsyncTimeoutException, self).__init__(msg)


class HttpContext(object):
    """封装请求和相应的基本数据"""

    def __init__(self, sock, host, port, method, url, data, callback, timeout=5):
        """
        sock: 请求的客户端socket对象
        host: 请求的主机名
        port: 请求的端口
        port: 请求的端口
        method: 请求方式
        url: 请求的URL
        data: 请求时请求体中的数据
        callback: 请求完成后的回调函数
        timeout: 请求的超时时间
        """
        self.sock = sock
        self.callback = callback
        self.host = host
        self.port = port
        self.method = method
        self.url = url
        self.data = data

        self.timeout = timeout

        self.__start_time = time.time()
        self.__buffer = []

    def is_timeout(self):
        """当前请求是否已经超时"""
        current_time = time.time()
        if (self.__start_time + self.timeout) < current_time:
            return True

    def fileno(self):
        """请求sockect对象的文件描述符，用于select监听"""
        return self.sock.fileno()

    def write(self, data):
        """在buffer中写入响应内容"""
        self.__buffer.append(data)

    def finish(self, exc=None):
        """在buffer中写入响应内容完成，执行请求的回调函数"""
        if not exc:
            response = b\'\'.join(self.__buffer)
            self.callback(self, response, exc)
        else:
            self.callback(self, None, exc)

    def send_request_data(self):
        content = """%s %s HTTP/1.0\r\nHost: %s\r\n\r\n%s""" % (
            self.method.upper(), self.url, self.host, self.data,)

        return content.encode(encoding=\'utf8\')


class AsyncRequest(object):
    def __init__(self):
        self.fds = []
        self.connections = []

    def add_request(self, host, port, method, url, data, callback, timeout):
        """创建一个要请求"""
        client = socket.socket()
        client.setblocking(False)
        try:
            client.connect((host, port))
        except BlockingIOError as e:
            pass
            # print(\'已经向远程发送连接的请求\')
        req = HttpContext(client, host, port, method, url, data, callback, timeout)
        self.connections.append(req)
        self.fds.append(req)

    def check_conn_timeout(self):
        """检查所有的请求，是否有已经连接超时，如果有则终止"""
        timeout_list = []
        for context in self.connections:
            if context.is_timeout():
                timeout_list.append(context)
        for context in timeout_list:
            context.finish(AsyncTimeoutException(\'请求超时\'))
            self.fds.remove(context)
            self.connections.remove(context)

    def running(self):
        """事件循环，用于检测请求的socket是否已经就绪，从而执行相关操作"""
        while True:
            r, w, e = select.select(self.fds, self.connections, self.fds, 0.05)

            if not self.fds:
                return

            for context in r:
                sock = context.sock
                while True:
                    try:
                        data = sock.recv(8096)
                        if not data:
                            self.fds.remove(context)
                            context.finish()
                            break
                        else:
                            context.write(data)
                    except BlockingIOError as e:
                        break
                    except TimeoutError as e:
                        self.fds.remove(context)
                        self.connections.remove(context)
                        context.finish(e)
                        break

            for context in w:
                # 已经连接成功远程服务器，开始向远程发送请求数据
                if context in self.fds:
                    data = context.send_request_data()
                    context.sock.sendall(data)
                    self.connections.remove(context)

            self.check_conn_timeout()


if __name__ == \'__main__\':
    def callback_func(context, response, ex):
        """
        :param context: HttpContext对象，内部封装了请求相关信息
        :param response: 请求响应内容
        :param ex: 是否出现异常（如果有异常则值为异常对象；否则值为None）
        :return:
        """
        print(context, response, ex)

    obj = AsyncRequest()
    url_list = [
        {\'host\': \'www.google.com\', \'port\': 80, \'method\': \'GET\', \'url\': \'/\', \'data\': \'\', \'timeout\': 5,
         \'callback\': callback_func},
        {\'host\': \'www.baidu.com\', \'port\': 80, \'method\': \'GET\', \'url\': \'/\', \'data\': \'\', \'timeout\': 5,
         \'callback\': callback_func},
        {\'host\': \'www.bing.com\', \'port\': 80, \'method\': \'GET\', \'url\': \'/\', \'data\': \'\', \'timeout\': 5,
         \'callback\': callback_func},
    ]
    for item in url_list:
        print(item)
        obj.add_request(**item)

    obj.running()

史上最牛逼的异步IO模块

Scrapy

Scrapy，Python开发的一个快速、高层次的屏幕抓取和web抓取框架，用于抓取web站点并从页面中提取结构化的数据。Scrapy用途广泛，可以用于数据挖掘、监测和自动化测试。 Scrapy吸引人的地方在于它是一个框架，任何人都可以根据需求方便的修改。它也提供了多种类型爬虫的基类，如BaseSpider、sitemap爬虫等，最新版本又提供了web2.0爬虫的支持。 Scrap，是碎片的意思，这个Python的爬虫框架叫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

1. 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] <name> <domain>
   - 创建爬虫应用
   如：
      scrapy gensipider -t basic baidu baidu.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             # 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）
   project_name/
       __init__.py
       items.py           # 设置数据存储模板，用于结构化数据，如：Django的Model
       pipelines.py       # 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
           __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

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

爬虫1.py

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

关于windows编码

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 = """<!DOCTYPE html>
<html>
    <head lang="en">
        <meta charset="UTF-8">
        <title></title>
    </head>
    <body>
        <ul>
            <li class="item-"><a id=\'i1\' href="link.html">first item</a></li>
            <li class="item-0"><a id=\'i2\' href="llink.html">first item</a></li>
            <li class="item-1"><a href="llink2.html">second item<span>vv</span></a></li>
        </ul>
        <div><a href="llink2.html">second item</a></div>
    </body>
</html>
"""
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)

# -*- coding: utf-8 -*-
import scrapy
from scrapy.selector import HtmlXPathSelector
from scrapy.http.request import Request
from scrapy.http.cookies import CookieJar
from scrapy import FormRequest


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

    cookie_dict = {}
    has_request_set = {}

    def start_requests(self):
        url = \'http://dig.chouti.com/\'
        # return [Request(url=url, callback=self.login)]
        yield Request(url=url, callback=self.login)

    def login(self, response):
        cookie_jar = CookieJar()
        cookie_jar.extract_cookies(response, response.request)
        for k, v in cookie_jar._cookies.items():
            for i, j in v.items():
                for m, n in j.items():
                    self.cookie_dict[m] = n.value

        req = Request(
            url=\'http://dig.chouti.com/login\',
            method=\'POST\',
            headers={\'Content-Type\': \'application/x-www-form-urlencoded; charset=UTF-8\'},
            body=\'phone=8615131255089&password=pppppppp&oneMonth=1\',
            cookies=self.cookie_dict,
            callback=self.check_login
        )
        yield req

    def check_login(self, response):
        req = Request(
            url=\'http://dig.chouti.com/\',
            method=\'GET\',
            callback=self.show,
            cookies=self.cookie_dict,
            dont_filter=True
        )
        yield req

    def show(self, response):
        # print(response)
        hxs = HtmlXPathSelector(response)
        news_list = hxs.select(\'//div[@id="content-list"]/div[@class="item"]\')
        for new in news_list:
            # temp = new.xpath(\'div/div[@class="part2"]/@share-linkid\').extract()
            link_id = new.xpath(\'*/div[@class="part2"]/@share-linkid\').extract_first()
            yield Request(
                url=\'http://dig.chouti.com/link/vote?linksId=%s\' %(link_id,),
                method=\'POST\',
                cookies=self.cookie_dict,
                callback=self.do_favor
            )

        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
            import hashlib
            hash = hashlib.md5()
            hash.update(bytes(page_url,encoding=\'utf-8\'))
            key = hash.hexdigest()
            if key in self.has_request_set:
                pass
            else:
                self.has_request_set[key] = page_url
                yield Request(
                    url=page_url,
                    method=\'GET\',
                    callback=self.show
                )

    def do_favor(self, response):
        print(response.text)

示例：自动登陆抽屉并点赞

# -*- coding: utf-8 -*-
import scrapy
from scrapy.http.response.html import HtmlResponse
from scrapy.http import Request
from scrapy.http.cookies import CookieJar


class ChoutiSpider(scrapy.Spider):
    name = "chouti"
    allowed_domains = ["chouti.com"]
    start_urls = (
        \'http://www.chouti.com/\',
    )

    def start_requests(self):
        url = \'http://dig.chouti.com/\'
        yield Request(url=url, callback=self.login, meta={\'cookiejar\': True})

    def login(self, response):
        print(response.headers.getlist(\'Set-Cookie\'))
        req = Request(
            url=\'http://dig.chouti.com/login\',
            method=\'POST\',
            headers={\'Content-Type\': \'application/x-www-form-urlencoded; charset=UTF-8\'},
            body=\'phone=8613121758648&password=woshiniba&oneMonth=1\',
            callback=self.check_login,
            meta={\'cookiejar\': True}
        )
        yield req

    def check_login(self, response):
        print(response.text)

处理Cookie

注意：settings.py中设置DEPTH_LIMIT = 1来指定“递归”的层数。

5. 格式化处理

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。

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

spiders/xiahuar.py

import scrapy


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

items

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

pipelines

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。

settings

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\')

自定义pipeline

6.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

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

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()

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

import sys
from scrapy.cmdline import execute

if __name__ == \'__main__\':
    execute(["scrapy","github","--nolog"])

单个爬虫

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\')

View Code

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

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)

自定义URL去重操作

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
# 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

"""
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,
# }

settings

11. 大文件下载

示例文件：猛击下载

11.TinyScrapy

from twisted.web.client import getPage
from twisted.internet import reactor
from twisted.internet import defer

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


def callback(arg):
    print(\'回来一个\', arg)


defer_list = []
for url in url_list:
    ret = getPage(bytes(url, encoding=\'utf8\'))
    ret.addCallback(callback)
    defer_list.append(ret)


def stop(arg):
    print(\'已经全部现在完毕\', arg)
    reactor.stop()


d = defer.DeferredList(defer_list)
d.addBoth(stop)

reactor.run()

twisted示例一

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from twisted.web.client import getPage
from twisted.internet import reactor
from twisted.internet import defer


@defer.inlineCallbacks
def task(url):
    ret = getPage(bytes(url, encoding=\'utf8\'))
    ret.addCallback(callback)
    yield ret


def callback(arg):
    print(\'回来一个\', arg)


url_list = [\'http://www.bing.com\', \'http://www.baidu.com\', ]
defer_list = []
for url in url_list:
    ret = task(url)
    defer_list.append(ret)


def stop(arg):
    print(\'已经全部现在完毕\', arg)
    reactor.stop()


d = defer.DeferredList(defer_list)
d.addBoth(stop)
reactor.run()

twisted示例二

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from twisted.internet import defer
from twisted.web.client import getPage
from twisted.internet import reactor
import threading


def _next_request():
    _next_request_from_scheduler()


def _next_request_from_scheduler():
    ret = getPage(bytes(\'http://www.chouti.com\', encoding=\'utf8\'))
    ret.addCallback(callback)
    ret.addCallback(lambda _: reactor.callLater(0, _next_request))


_closewait = None

@defer.inlineCallbacks
def engine_start():
    global _closewait
    _closewait = defer.Deferred()
    yield _closewait


@defer.inlineCallbacks
def task(url):
    reactor.callLater(0, _next_request)
    yield engine_start()


counter = 0
def callback(arg):
    global counter
    counter +=1
    if counter == 10:
        _closewait.callback(None)
    print(\'one\', len(arg))


def stop(arg):
    print(\'all done\', arg)
    reactor.stop()


if __name__ == \'__main__\':
    url = \'http://www.cnblogs.com\'

    defer_list = []
    deferObj = task(url)
    defer_list.append(deferObj)

    v = defer.DeferredList(defer_list)
    v.addBoth(stop)
    reactor.run()

twisted示例三

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from twisted.web.client import getPage, defer
from twisted.internet import reactor
import queue


class Response(object):
    def __init__(self, body, request):
        self.body = body
        self.request = request
        self.url = request.url

    @property
    def text(self):
        return self.body.decode(\'utf-8\')


class Request(object):
    def __init__(self, url, callback=None):
        self.url = url
        self.callback = callback


class Scheduler(object):
    def __init__(self, engine):
        self.q = queue.Queue()
        self.engine = engine

    def enqueue_request(self, request):
        self.q.put(request)

    def next_request(self):
        try:
            req = self.q.get(block=False)
        except Exception as e:
            req = None

        return req

    def size(self):
        return self.q.qsize()


class ExecutionEngine(object):
    def __init__(self):
        self._closewait = None
        self.running = True
        self.start_requests = None
        self.scheduler = Scheduler(self)

        self.inprogress = set()

    def check_empty(self, response):
        if not self.running:
            self._closewait.callback(\'......\')

    def _next_request(self):
        while self.start_requests:
            try:
                request = next(self.start_requests)
            except StopIteration:
                self.start_requests = None
            else:
                self.scheduler.enqueue_request(request)

        while len(self.inprogress) < 5 and self.scheduler.size() > 0:  # 最大并发数为5

            request = self.scheduler.next_request()
            if not request:
                break

            self.inprogress.add(request)
            d = getPage(bytes(request.url, encoding=\'utf-8\'))
            d.addBoth(self._handle_downloader_output, request)
            d.addBoth(lambda x, req: self.inprogress.remove(req), request)
            d.addBoth(lambda x: self._next_request())

        if len(self.inprogress) == 0 and self.scheduler.size() == 0:
            self._closewait.callback(None)

    def _handle_downloader_output(self, body, request):
        """
        获取内容，执行回调函数，并且把回调函数中的返回值获取，并添加到队列中
        :param response: 
        :param request: 
        :return: 
        """
        import types

        response = Response(body, request)
        func = request.callback or self.spider.parse
        gen = func(response)
        if isinstance(gen, types.GeneratorType):
            for req in gen:
                self.scheduler.enqueue_request(req)

    @defer.inlineCallbacks
    def start(self):
        self._closewait = defer.Deferred()
        yield self._closewait

    def open_spider(self, spider, start_requests):
        self.start_requests = start_requests
        self.spider = spider
        reactor.callLater(0, self._next_request)


class Crawler(object):
    def __init__(self, spidercls):
        self.spidercls = spidercls

        self.spider = None
        self.engine = None

    @defer.inlineCallbacks
    def crawl(self):
        self.engine = ExecutionEngine()
        self.spider = self.spidercls()
        start_requests = iter(self.spider.start_requests())
        start_requests = iter(start_requests)
        self.engine.open_spider(self.spider, start_requests)
        yield self.engine.start()


class CrawlerProcess(object):
    def __init__(self):
        self._active = set()
        self.crawlers = set()

    def crawl(self, spidercls, *args, **kwargs):
        crawler = Crawler(spidercls)

        self.crawlers.add(crawler)
        d = crawler.crawl(*args, **kwargs)
        self._active.add(d)
        return d

    def start(self):
        dl = defer.DeferredList(self._active)
        dl.addBoth(self._stop_reactor)
        reactor.run()

    def _stop_reactor(self, _=None):
        reactor.stop()


class Spider(object):
    def start_requests(self):
        for url in self.start_urls:
            yield Request(url)


class ChoutiSpider(Spider):
    name = "chouti"
    start_urls = [
        \'http://dig.chouti.com/\',
    ]

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


class CnblogsSpider(Spider):
    name = "cnblogs"
    start_urls = [
        \'http://www.cnblogs.com/\',
    ]

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


if __name__ == \'__main__\':

    spider_cls_list = [ChoutiSpider, CnblogsSpider]

    crawler_process = CrawlerProcess()
    for spider_cls in spider_cls_list:
        crawler_process.crawl(spider_cls)

    crawler_process.start()

模拟scrapy框架

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import types
from twisted.internet import defer
from twisted.web.client import getPage
from twisted.internet import reactor



class Request(object):
    def __init__(self, url, callback):
        self.url = url
        self.callback = callback
        self.priority = 0


class HttpResponse(object):
    def __init__(self, content, request):
        self.content = content
        self.request = request


class ChouTiSpider(object):

    def start_requests(self):
        url_list = [\'http://www.cnblogs.com/\', \'http://www.bing.com\']
        for url in url_list:
            yield Request(url=url, callback=self.parse)

    def parse(self, response):
        print(response.request.url)
        # yield Request(url="http://www.baidu.com", callback=self.parse)




from queue import Queue
Q = Queue()


class CallLaterOnce(object):
    def __init__(self, func, *a, **kw):
        self._func = func
        self._a = a
        self._kw = kw
        self._call = None

    def schedule(self, delay=0):
        if self._call is None:
            self._call = reactor.callLater(delay, self)

    def cancel(self):
        if self._call:
            self._call.cancel()

    def __call__(self):
        self._call = None
        return self._func(*self._a, **self._kw)


class Engine(object):
    def __init__(self):
        self.nextcall = None
        self.crawlling = []
        self.max = 5
        self._closewait = None

    def get_response(self,content, request):
        response = HttpResponse(content, request)
        gen = request.callback(response)
        if isinstance(gen, types.GeneratorType):
            for req in gen:
                req.priority = request.priority + 1
                Q.put(req)


    def rm_crawlling(self,response,d):
        self.crawlling.remove(d)

    def _next_request(self,spider):
        if Q.qsize() == 0 and len(self.crawlling) == 0:
            self._closewait.callback(None)

        if len(self.crawlling) >= 5:
            return
        while len(self.crawlling) < 5:
            try:
                req = Q.get(block=False)
            except Exception as e:
                req = None
            if not req:
                return
            d = getPage(req.url.encode(\'utf-8\'))
            self.crawlling.append(d)
            d.addCallback(self.get_response, req)
            d.addCallback(self.rm_crawlling,d)
            d.addCallback(lambda _: self.nextcall.schedule())


    @defer.inlineCallbacks
    def crawl(self):
        spider = ChouTiSpider()
        start_requests = iter(spider.start_requests())
        flag = True
        while flag:
            try:
                req = next(start_requests)
                Q.put(req)
            except StopIteration as e:
                flag = False

        self.nextcall = CallLaterOnce(self._next_request,spider)
        self.nextcall.schedule()

        self._closewait = defer.Deferred()
        yield self._closewait

    @defer.inlineCallbacks
    def pp(self):
        yield self.crawl()

_active = set()
obj = Engine()
d = obj.crawl()
_active.add(d)

li = defer.DeferredList(_active)
li.addBoth(lambda _,*a,**kw: reactor.stop())

reactor.run()

参考版

点击下载

更多文档参见：http://scrapy-chs.readthedocs.io/zh_CN/latest/index.html