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 requestsdef fetch_async(url):    response = requests.get(url)    return responseurl_list = ['http://www.github.com', 'http://www.bing.com']for url in url_list:    fetch_async(url)

from concurrent.futures import ThreadPoolExecutorimport requestsdef fetch_async(url):    response = requests.get(url)    return responseurl_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)

from concurrent.futures import ThreadPoolExecutorimport requestsdef fetch_async(url):    response = requests.get(url)    return responsedef 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)

from concurrent.futures import ProcessPoolExecutorimport requestsdef fetch_async(url):    response = requests.get(url)    return responseurl_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)

from concurrent.futures import ProcessPoolExecutorimport requestsdef fetch_async(url):    response = requests.get(url)    return responsedef 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回事首选：

import asyncio@asyncio.coroutinedef 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()

import asyncio@asyncio.coroutinedef 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()

import aiohttpimport asyncio@asyncio.coroutinedef 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()

import asyncioimport requests@asyncio.coroutinedef 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()

import geventimport requestsfrom gevent import monkeymonkey.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={}),# ])

import grequestsrequest_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)

from twisted.web.client import getPage, deferfrom twisted.internet import reactordef 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()

from tornado.httpclient import AsyncHTTPClientfrom tornado.httpclient import HTTPRequestfrom tornado import ioloopdef 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()

from twisted.internet import reactorfrom twisted.web.client import getPageimport urllib.parsedef 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()

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 selectimport socketimport timeclass 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()

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：

1. 引擎从调度器中取出一个链接(URL)用于接下来的抓取
2. 引擎把URL封装成一个请求(Request)传给下载器
3. 下载器把资源下载下来，并封装成应答包(Response)
4. 爬虫解析Response
5. 解析出实体（Item）,则交给实体管道进行进一步的处理
6. 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 scrapyWindows      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] 
      
      
          - 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

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

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

3. 小试牛刀

import scrapyfrom scrapy.selector import HtmlXPathSelectorfrom scrapy.http.request import Requestclass 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, HtmlXPathSelectorfrom scrapy.http import HtmlResponsehtml = """            
                             
     
            
      
first item
gt;            
      
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)

# -*- coding: utf-8 -*-import scrapyfrom scrapy.selector import HtmlXPathSelectorfrom scrapy.http.request import Requestfrom scrapy.http.cookies import CookieJarfrom scrapy import FormRequestclass 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)

# -*- coding: utf-8 -*-import scrapyfrom scrapy.http.response.html import HtmlResponsefrom scrapy.http import Requestfrom scrapy.http.cookies import CookieJarclass 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)

 

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 scrapyfrom scrapy.selector import HtmlXPathSelectorfrom scrapy.http.request import Requestfrom scrapy.http.cookies import CookieJarfrom scrapy import FormRequestclass 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

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

import jsonimport osimport requestsclass 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 itemclass 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 DropItemclass 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

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

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 

import sysfrom scrapy.cmdline import executeif __name__ == '__main__':    execute(["scrapy","github","--nolog"])

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 signalsclass 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')

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 = FalseJOBDIR = "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)

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.htmlSPIDER_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,# }

 

11. 大文件下载

示例文件：

11.TinyScrapy

from twisted.web.client import getPagefrom twisted.internet import reactorfrom twisted.internet import deferurl_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()

#!/usr/bin/env python# -*- coding:utf-8 -*-from twisted.web.client import getPagefrom twisted.internet import reactorfrom twisted.internet import defer@defer.inlineCallbacksdef task(url):    ret = getPage(bytes(url, encoding='utf8'))    ret.addCallback(callback)    yield retdef 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()

#!/usr/bin/env python# -*- coding:utf-8 -*-from twisted.internet import deferfrom twisted.web.client import getPagefrom twisted.internet import reactorimport threadingdef _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.inlineCallbacksdef engine_start():    global _closewait    _closewait = defer.Deferred()    yield _closewait@defer.inlineCallbacksdef task(url):    reactor.callLater(0, _next_request)    yield engine_start()counter = 0def 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()

#!/usr/bin/env python# -*- coding:utf-8 -*-from twisted.web.client import getPage, deferfrom twisted.internet import reactorimport queueclass 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 = callbackclass 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()

#!/usr/bin/env python# -*- coding:utf-8 -*-import typesfrom twisted.internet import deferfrom twisted.web.client import getPagefrom twisted.internet import reactorclass Request(object):    def __init__(self, url, callback):        self.url = url        self.callback = callback        self.priority = 0class HttpResponse(object):    def __init__(self, content, request):        self.content = content        self.request = requestclass 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 QueueQ = 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()

 

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