Scrapy学习笔记(7)-定制动态可配置爬虫
前言
最近一直想维护一个代理IP池，在网上找了三十多个免费提供代理IP的网站，想把这些代理都抓取下来存到本地数据库，再写一个守护进程定时去验证可用性和连接速度，剔除失效代理，以此来保证库里面始终都有特定数量的优质代理IP。那么问题来了，这么多网站每个网站的页面布局或者说网页源码都不一样，数据抓取规则也不一样，如果针对每个网站都硬编码一份spider代码，这工作量貌似有点大，而且一旦目标站点调整布局，我们之前写好的spider代码很可能就得再次修改。此时我迫切地希望能有一个框架可以通过只写一份spider代码和维护多个网站的爬取规则，就能自动抓取这些网站的信息，很庆幸的是强大的Scrapy 可以做到这点，本文记录实现过程。
技术点
1.根据爬取规则自动生成spider
2.使用Scrapy核心API操作spider
3.Linux下Redis的安装和使用
4.基于Redis和SQLAlchemy对Scrapy Item去重并存储
实现过程
笔者系统为centos，关于Redis的安装和配置可以参考这里：http://jinbitou.net/2016/10/28/2110.html，windows环境的读者请自行Google。本次项目的目录结构如下：
主要文件和目录解释：
model目录存放的是数据库表的映射文件
spiders目录存放的是spider代码
initDB.py是用来初始化数据库的，自动根据model目录下的映射文件在数据库中建好相应的表
pipelines.py实现将抓取到的数据持久化到数据库
proxy_middlewares.py自定义中间件，用来设定代理IP
useragent_middlewares.py自定义中间件，用来随机切换UA
run.py总控脚本，从规则表中读取规则，动态生成spider并启动
废话不多说，上代码！
__init__.py（文件1）
# -*- coding: utf-8 -*-from sqlalchemy.ext.declarative import declarative_basefrom sqlalchemy import create_enginefrom sqlalchemy.orm import sessionmaker# 创建对象的基类:Base = declarative_base()# 初始化数据库连接:engine = create_engine('mysql+mysqldb://root:123456@localhost:3306/scrapy?charset=utf8')#返回数据库会话def loadSession(): Session = sessionmaker(bind=engine) session = Session() return session
proxy.py（文件2）
from sqlalchemy import Column,String,Integer,DateTimefrom . import Baseimport datetimeclass Proxy(Base):#继承Base类 __tablename__ = 'proxies' ip_port= Column(String(30),primary_key=True,nullable=False)#主键 type= Column(String(20),nullable=True,default="")#协议类型 level= Column(String(20),nullable=True,default="")#匿名级别 location= Column(String(100),nullable=True,default="")#ip所在地区 speed= Column(String(20),nullable=True,default="")#连接速度 lifetime = Column(String(20),nullable=True,default="")#生存时间 lastcheck = Column(String(20),nullable=True,default="")#最后校验时间 source = Column(String(500), nullable=False)#页面地址 rule_id = Column(Integer,nullable=False)#规则(网站/spider)id indate = Column(DateTime,nullable=False)#入库时间 def __init__(self,ip_port,source,type,level,location,speed,lifetime,lastcheck,rule_id): self.ip_port=ip_port
self.type=type
self.level=level
self.location=location
self.speed=speed
self.source=source
self.lifetime=lifetime
self.lastcheck=lastcheck
self.rule_id=rule_id
self.indate=datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
rules.py（文件3）
# -*- coding: utf-8 -*-from sqlalchemy import Column,String,Integerfrom sqlalchemy import Sequencefrom . import Baseclass Rule(Base): __tablename__ = 'rules' # 表结构: id = Column(Integer, Sequence('id',start=1,increment=1),primary_key=True)#设定自增长主键 name = Column(String(100),nullable=False)#spider的名字 allowed_domains = Column(String(500),nullable=False)#允许爬取的域 start_urls = Column(String(500),nullable=False)#开始爬取的入口 next_page = Column(String(500),nullable=False,default="")#xpath表达式，爬取下一页 allow_url = Column(String(500),nullable=False)#正则表达式，匹配符合要求的链接 extract_from = Column(String(500),nullable=False,default="")#xpath表达式，限制解析区域 loop_xpath = Column(String(500),nullable=False)#xpath表达式，控制单页面循环次数 ip_xpath = Column(String(500),nullable=False)#xpath表达式，解析IP port_xpath = Column(String(500),nullable=False,default="")#xpath表达式，解析端口 location1_xpath = Column(String(500),nullable=False)#xpath表达式，解析区域 location2_xpath = Column(String(500),nullable=False,default="")#xpath表达式，解析区域 speed_xpath = Column(String(500),nullable=False,default="")#xpath表达式，解析连接速度 lifetime_xpath = Column(String(500),nullable=False,default="")#xpath表达式，解析生存时间 type_xpath = Column(String(500),nullable=False,default="")#xpath表达式，解析协议类别 level_xpath = Column(String(500),nullable=False,default="")#xpath表达式，解析匿名级别 lastcheck_xpath = Column(String(500),nullable=False,default="")#xpath表达式，解析最后校验时间 enable = Column(Integer,nullable=False)#激活rule的开关，1为开0为关
proxy_spider.py（文件4）
# -*- coding: utf-8 -*-import scrapyfrom scrapy.linkextractors import LinkExtractorfrom scrapy.spiders import CrawlSpider, Rule#抓取信息的数据结构，类似于javabeanclass IpProxyPoolItem(scrapy.Item): ip_port = scrapy.Field() type = scrapy.Field() level = scrapy.Field() location = scrapy.Field() speed = scrapy.Field() lifetime = scrapy.Field() lastcheck = scrapy.Field() rule_id = scrapy.Field() source = scrapy.Field()#搭建spider的主体框架，继承CrawlSpider类class ProxySpiderSpider(CrawlSpider): name = 'MagicSpider' def __init__(self,rule): self.rule = rule
self.name = rule.name
#spilt函数通过分隔符分割字符串，得到列表类型 self.allowed_domains = rule.allowed_domains.split(',') self.start_urls = rule.start_urls.split(',') rule_list = [] # 添加"下一页"链接的规则 if len(rule.next_page): rule_list.append(Rule(LinkExtractor(restrict_xpaths=rule.next_page), follow=True)) #链接提取规则 rule_list.append(Rule(LinkExtractor( allow=rule.allow_url.split(','), unique=True),#链接去重 follow=True,#跟随爬取 callback='parse_item'))#调用parse_item提取数据 #使用tuple()将列表转换为元组 self.rules = tuple(rule_list) #当有子类继承ProxySpiderSpider的时候，调用初始化方法启动爬取过程 super(ProxySpiderSpider, self).__init__() def parse_item(self, response): item=IpProxyPoolItem() if len(self.rule.loop_xpath): for proxy in response.xpath(self.rule.loop_xpath): if len(self.rule.ip_xpath): tmp_ip = proxy.xpath(self.rule.ip_xpath).extract_first() #strip函数用来删除空白字符(包括'\n', '\r', '\t', ' ') ip = tmp_ip.strip() if tmp_ip is not None else "" else: ip = "" if len(self.rule.port_xpath): tmp_port = proxy.xpath(self.rule.port_xpath).extract_first() port = tmp_port.strip() if tmp_port is not None else "" else: port = "" if len(self.rule.location1_xpath): tmp_location1 = proxy.xpath(self.rule.location1_xpath).extract_first() location1 = tmp_location1.strip() if tmp_location1 is not None else "" else: location1 = "" if len(self.rule.location2_xpath): tmp_location2 = proxy.xpath(self.rule.location2_xpath).extract_first() location2 = tmp_location2.strip() if tmp_location2 is not None else "" else: location2 = "" if len(self.rule.lifetime_xpath): tmp_lifetime = proxy.xpath(self.rule.lifetime_xpath).extract_first() lifetime = tmp_lifetime.strip() if tmp_lifetime is not None else "" else: lifetime = "" if len(self.rule.lastcheck_xpath): tmp_lastcheck = proxy.xpath(self.rule.lastcheck_xpath).extract_first() lastcheck = tmp_lastcheck.strip() if tmp_lastcheck is not None else "" else: lastcheck = "" if len(self.rule.level_xpath): tmp_level = proxy.xpath(self.rule.level_xpath).extract_first() level = tmp_level.strip() if tmp_level is not None else "" else: level = "" if len(self.rule.type_xpath): tmp_type = proxy.xpath(self.rule.type_xpath).extract_first() type = tmp_type.strip() if tmp_type is not None else "" else: type = "" if len(self.rule.speed_xpath): tmp_speed = proxy.xpath(self.rule.speed_xpath).extract_first() speed = tmp_speed.strip() if tmp_speed is not None else "" else: speed = "" #join函数用来拼接字符串，接收的参数为列表类型 item['ip_port']=(":".join([ip,port])) if len(port) else ip
item['type']=type
item['level']=level
item['location']=(" ".join([location1,location2])) if location2 is not None and len(location2) else location1
item['speed']=speed
item['lifetime']=lifetime
item['lastcheck']=lastcheck
item['rule_id']=self.rule.id
item['source']=response.url
yield item
pipelines.py（文件6）
# -*- coding: utf-8 -*-import MySQLdbfrom scrapy.exceptions import DropItemimport redisfrom model import loadSessionfrom model import proxyfrom scrapy import logimport loggingRedis = redis.StrictRedis(host='localhost',port=6379,db=0)# item去重class DuplicatesPipeline(object): def process_item(self, item, spider): if Redis.exists('ip_port:%s' % item['ip_port']) : raise DropItem("Duplicate item found: %s" % item) else: Redis.set('ip_port:%s' % item['ip_port'],1) return item#数据入库class IpProxyPoolPipeline(object): def process_item(self, item, spider): if len(item['ip_port']): a = proxy.Proxy( ip_port=item['ip_port'], type=item['type'], level=item['level'], location=item['location'], speed=item['speed'], lifetime=item['lifetime'], lastcheck=item['lastcheck'], rule_id=item['rule_id'], source=item['source'] ) session = loadSession() try: session.merge(a) session.commit() except MySQLdb.IntegrityError, e: log.msg("MySQL Error: %s" % str(e), _level=logging.WARNING) return item
else: log.msg("ip_port is invalid!",_level=logging.WARNING)
proxy_middlewares.py（文件7）
# -*- coding: utf-8 -*-import randomfrom scrapy import logimport loggingclass ProxyMiddleware(object): proxyList = [ \
'124.88.67.18:80', '124.88.67.52:843', '110.77.169.30:8080', '58.246.194.70:8080', '159.232.214.68:8080' ] def process_request(self, request, spider): # 从代理IP列表中随机选择一个 pro_adr = random.choice(self.proxyList) log.msg("Current Proxy <%s>" % pro_adr,_level=logging.INFO) request.meta['proxy'] = "http://" + pro_adr
useragent_middlewares.py（文件9）
# -*-coding:utf-8-*-from scrapy import logimport logging'''
#避免被ban策略之一：使用useragent池。
'''import randomfrom scrapy.downloadermiddlewares.useragent import UserAgentMiddlewareclass UserAgent(UserAgentMiddleware): def __init__(self, user_agent=''): self.user_agent = user_agent
def process_request(self, request, spider): ua = random.choice(self.user_agent_list) if ua: #显示当前使用的useragent #print "********Current UserAgent:%s************" %ua #记录 log.msg('Current UserAgent: '+ua, _level=logging.INFO) request.headers.setdefault('User-Agent', ua) user_agent_list = [\
"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.1 " "(KHTML, like Gecko) Chrome/22.0.1207.1 Safari/537.1", "Mozilla/5.0 (X11; CrOS i686 2268.111.0) AppleWebKit/536.11 " "(KHTML, like Gecko) Chrome/20.0.1132.57 Safari/536.11", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.6 " "(KHTML, like Gecko) Chrome/20.0.1092.0 Safari/536.6", "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.6 " "(KHTML, like Gecko) Chrome/20.0.1090.0 Safari/536.6", "Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.1 " "(KHTML, like Gecko) Chrome/19.77.34.5 Safari/537.1", "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/536.5 " "(KHTML, like Gecko) Chrome/19.0.1084.9 Safari/536.5", "Mozilla/5.0 (Windows NT 6.0) AppleWebKit/536.5 " "(KHTML, like Gecko) Chrome/19.0.1084.36 Safari/536.5", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 " "(KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3", "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/536.3 " "(KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_0) AppleWebKit/536.3 " "(KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3", "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 " "(KHTML, like Gecko) Chrome/19.0.1062.0 Safari/536.3", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 " "(KHTML, like Gecko) Chrome/19.0.1062.0 Safari/536.3", "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 " "(KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 " "(KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3", "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/536.3 " "(KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3", "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 " "(KHTML, like Gecko) Chrome/19.0.1061.0 Safari/536.3", "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/535.24 " "(KHTML, like Gecko) Chrome/19.0.1055.1 Safari/535.24", "Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/535.24 " "(KHTML, like Gecko) Chrome/19.0.1055.1 Safari/535.24", "Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_6_8; en-us) AppleWebKit/534.50" "(KHTML, like Gecko) Version/5.1 Safari/534.50", "Mozilla/5.0 (Windows; U; Windows NT 6.1; en-us) AppleWebKit/534.50"
"(KHTML, like Gecko) Version/5.1 Safari/534.50", "Mozilla/5.0 (Windows NT 10.0; WOW64; rv:38.0) Gecko/20100101 Firefox/38.0", "Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0;" ".NET4.0C; .NET4.0E; .NET CLR 2.0.50727; .NET CLR 3.0.30729; .NET CLR 3.5.30729; InfoPath.3; rv:11.0) like Gecko", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_0) AppleWebKit/535.11 " "(KHTML, like Gecko) Chrome/17.0.963.56 Safari/535.11", "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; 360SE)", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; " "AcooBrowser; .NET CLR 1.1.4322; .NET CLR 2.0.50727)", "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; " "Acoo Browser; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.0.04506)", "Mozilla/4.0 (compatible; MSIE 7.0; AOL 9.5; " "AOLBuild 4337.35; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)", "Mozilla/5.0 (Windows; U; MSIE 9.0; Windows NT 9.0; en-US)", "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; " "Win64; x64; Trident/5.0; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET CLR 2.0.50727; Media Center PC 6.0)", "Mozilla/5.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; WOW64; " "Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET CLR 1.0.3705; .NET CLR 1.1.4322)", "Mozilla/4.0 (compatible; MSIE 7.0b; Windows NT 5.2; .NET CLR 1.1.4322; .NET CLR 2.0.50727; " "InfoPath.2; .NET CLR 3.0.04506.30)", "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN) AppleWebKit/523.15 " "(KHTML, like Gecko, Safari/419.3) Arora/0.3 (Change: 287 c9dfb30)", "Mozilla/5.0 (X11; U; Linux; en-US) AppleWebKit/527+ (KHTML, like Gecko, Safari/419.3) Arora/0.6", "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.2pre) Gecko/20070215 K-Ninja/2.1.1", "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9) Gecko/20080705 Firefox/3.0 Kapiko/3.0", "Mozilla/5.0 (X11; Linux i686; U;) Gecko/20070322 Kazehakase/0.4.5", "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.8) Gecko Fedora/1.9.0.8-1.fc10 Kazehakase/0.5.6", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.56 Safari/535.11", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_3) AppleWebKit/535.20 " "(KHTML, like Gecko) Chrome/19.0.1036.7 Safari/535.20", "Opera/9.80 (Macintosh; Intel Mac OS X 10.6.8; U; fr) Presto/2.9.168 Version/11.52" ]
initDB.py（文件5）
初始化数据库，自动建好所需的数据库表，并添加了一条规则# -*- coding: utf-8 -*-from model import loadSessionfrom model import proxyfrom model.rules import Rulefrom model import Base,engine#寻找Base的所有子类，并在数据库中生成表Base.metadata.create_all(engine)#返回数据库会话session = loadSession()#实例化一个Rule对象item=Rule()item.name="ip84"item.allowed_domains="ip84.com"item.start_urls="http://ip84.com/gn/1"item.next_page="//a[@class='next_page']"item.allow_url="/gn/\d+"item.loop_xpath="//table[@class='list']/tr[position()>1]"item.ip_xpath="td[1]/text()"item.port_xpath="td[2]/text()"item.location1_xpath="td[3]/a[1]/text()"item.location2_xpath="td[3]/a[2]/text()"item.speed_xpath="td[6]/text()"item.type_xpath="td[5]/text()"item.level_xpath="td[4]/text()"item.enable="1"#添加到数据库session.add(item)session.commit()
run.py（文件8）
# -*- coding: utf-8 -*-from spiders.proxy_spider import ProxySpiderSpiderfrom model import loadSessionfrom model.rules import Rulefrom scrapy.crawler import CrawlerProcessfrom scrapy.settings import Settings#spider相关设置settings = Settings()'''
Scrapy框架的高度灵活性得益于其数据管道的架构设计，开发者可以通过简单的配置就能轻松地添加新特性。
我们可以通过如下的方式添加pipline。
'''settings.set("ITEM_PIPELINES" , { 'pipelines.DuplicatesPipeline': 200, 'pipelines.IpProxyPoolPipeline': 300,})#设置默认请求头settings.set("DEFAULT_REQUEST_HEADERS",{ 'Accept': 'text/html, application/xhtml+xml, application/xml', 'Accept-Language': 'zh-CN,zh;q=0.8'})#注册自定义中间件，激活切换UA的组件和切换代理IP的组件settings.set("DOWNLOADER_MIDDLEWARES",{ 'useragent_middlewares.UserAgent': 1, 'proxy_middlewares.ProxyMiddleware':100, 'scrapy.downloadermiddleware.useragent.UserAgentMiddleware' : None,})#设置爬取间隔settings.set("DOWNLOAD_DELAY",1)#禁用cookiessettings.get("COOKIES_ENABLED",False)#设定是否遵循目标站点robot.txt中的规则settings.get("ROBOTSTXT_OBEY",True)#加载设置process = CrawlerProcess(settings)session=loadSession()#取出规则表中已激活的rulerules = session.query(Rule).filter(Rule.enable == 1)for rule in rules: process.crawl(ProxySpiderSpider,rule)process.start()
开始爬取
shell中执行python run.py即可开始采集数据…
新增两个网站的爬取规则：
http://www.kuaidaili.com/free/
检验结果：
三条规则生成的spider在两个小时不到已经采集了6万多IP。
