Python scrapy爬虫学习笔记01

1、scrapy 新建项目

scrapy startproject 项目名称

2、spiders编写（以爬取163北京新闻为例）

此例中用到了scrapy的Itemloader机制，itemloader中有三个比较重要的方法，有add_xpath(),add_value(),add_css(),这三个方法中，都有两个参数第一个为item的名，第二个为值或者是提取规则

用法如下例。

1、scrapy 新建项目
 
scrapy startproject 项目名称
 
2、spiders编写（以爬取163北京新闻为例）
 
import json
import time
import scrapy
from scrapy.http import Request
from aticleSpider.items import ArticleItem
from aticleSpider.until.common import get_md5
from aticleSpider.items import ArticleItemLoader
# from scrapy.loader import ItemLoader
 
class ArticleSpider(scrapy.Spider):
    #spider名字，scrapy会读取这个name
    name = 'bj163news'
    #可允许爬取的域名
    allowed_domains = ['163.com']
    #url入口
    start_urls = ["http://bendi.news.163.com/beijing/special/04388GGG/bjxinxiliu.js?callback=data_callback&_="]
    num = 1
    times = time.time()
    add_time  = str(times).replace('.','')[0:13]
 
    def parse(self, response):
        """
        1、获取文章列表中的文章的url并进行具体字段的解析
        2、获取到下页的URL进行下载
        :param response:
        :return:
        """
        #解析列表页的所有文章的url
        response_str = str(response.body.decode("gbk", "ignore")).replace('data_callback(','').replace(')','')
        # print(response_str)
        js = json.loads(response_str)
        for line in js:
            keys = []
            title = line['title']
            commenturl= line['commenturl']
            docurl = line['docurl']
            newstype = line['newstype']
            title_img = line['imgurl']
            for keywords in line['keywords']:
                keys.append(keywords['keyname'])
            key_words = ','.join(keys)
            # print(docurl,'docurl')
            metas = {'title':title,'commenturl':commenturl,'newstype':newstype,'title_img':title_img,'key_words':key_words}
            yield Request(url=docurl,meta=metas,callback=self.parse_detail)
 
        #循环获取所有页面数据的方法
        self.num = self.num +1
        if self.num==10:
        str_num = str(self.num)
        else :
            str_num = ''+str(self.num)
 
        next_url = "http://bendi.news.163.com/beijing/special/04388GGG/bjxinxiliu_"+str_num+".js?callback=data_callback&_="+self.add_time
        #
        yield Request(url=next_url, callback=self.parse)
        if url:
            url_page = url
 
    #文章内容页数据爬取 item loader 模式
    def parse_detail(self,response):
        # item =ArticleItem()
        main_data = response.meta
        # docurl = response.url
        # # project_doc_url = get_md5(docurl)
        # # try:
        # news_editor = response.xpath('//span[@class="ep-editor"]/text()').extract_first("").replace('责任编辑：','')
        # news_source = response.xpath('//div[@class="ep-source cDGray"]/span/text()').extract_first("").replace('本文来源：','')
        # # except:
        source_title = response.xpath('//div[@id="endText"]/p[@class="otitle"]/text()').extract_first(" ").replace('（原标题：','').replace('）','').strip()
        # news_time = response.xpath('//div[@class="post_time_source"]//text()').extract_first("").replace('来源:','').strip()
        # content_org = response.xpath('//div[@id="endText"]').extract_first("")
        news_conts =response.xpath('//div[@id="endText"]/p')
        news_cont =[]
        for one_p in news_conts:
            img = one_p.xpath('.//img')
            # print(img)
            if img != []:
                img_url = one_p.xpath('.//@src').extract_first("")
                news_cont.append({'content':img_url,'type':'pic'})
            else:
                try:
                    text = one_p.xpath('.//text()').extract_first("")
                    if text.find('（原标题：')>0 or text =='':
                        continue
                    news_cont.append({'content':text,'type':'text'}).strip()
                except:
                    pass
　　　　 #注释部分为不用itemloader的提取方法
        # item['content_org'] =''
        # item['project_doc_url'] = project_doc_url
        # item['title'] = main_data.get('title','')  #get方法取值，并传默认值
        # item['source_title'] = source_title
        # item['commenturl'] = main_data.get('commenturl','')
        # item['newstype'] = main_data.get('newstype','')
        # item['docurl'] = docurl
        # item['title_img'] = [main_data.get('title_img','')]
        # item['key_words'] = main_data.get('key','')
        # item['news_editor'] = news_editor
        # item['news_source'] = news_source
        # item['news_time'] = news_time
        # item['news_cont'] = news_cont
        # yield item
 
        item_loader = ArticleItemLoader(item=ArticleItem(),response=response)
        item_loader.add_xpath('news_editor','//span[@class="ep-editor"]/text()')
        item_loader.add_value('title',main_data.get('title',''))
        item_loader.add_value('project_doc_url',get_md5(response.url))
        item_loader.add_value('commenturl',main_data.get('commenturl',''))
        item_loader.add_value('newstype',main_data.get('newstype',''))
        item_loader.add_value('docurl',response.url)
        item_loader.add_value('source_title',source_title)
        item_loader.add_value('title_img',[main_data.get('title_img','')])
        item_loader.add_value('key_words',main_data.get('key_words',''))
        item_loader.add_xpath('news_editor','//span[@class="ep-editor"]/text()')
        item_loader.add_xpath('news_source','//div[@class="ep-source cDGray"]/span/text()')
        item_loader.add_xpath('content_org','//div[@id="endText"]')
        item_loader.add_value('news_cont',news_cont)
        item_loader.add_xpath('news_time','//div[@class="post_time_source"]//text()')
 
        article_item = item_loader.load_item()
        yield article_item

3、使用item loader的item设计

# -*- coding: utf-8 -*-
 
# Define here the models for your scraped items
#
# See documentation in:
# http://doc.scrapy.org/en/latest/topics/items.html
 
import scrapy
from scrapy.loader import ItemLoader
from scrapy.loader.processors import TakeFirst, MapCompose
 
class ArticleSpiderItem(scrapy.Item):
    # define the fields for your item here like:
    # name = scrapy.Field()
    pass
 
#自定义article loader 设置默认输出值为list的第一个
class ArticleItemLoader(ItemLoader):
    # pass
    default_output_processor = TakeFirst()
 
#item loader的返回原本值，不做任何改变
def return_value(value):
    return value
 
#163时间格式化
def return_time(value):
    return value.replace('来源:','').strip()
 
#163格式化获取作者
def get_editor(value):
    # if value != '':
    return value.replace('责任编辑：','')
 
#163格式化获取本文来源
def get_source(value):
    # if value != '':
    return value.replace('本文来源：','')
 
#163item
class ArticleItem(scrapy.Item):
 
    """
    item= scrapy.Field()  Field() 有两个参数，即输入/输出处理器 一个为
     input_processor 输入处理器在数据被接受到时执行
     output_processor 输出处理器在ItemLoader.load_item()时再执行输出处理器，返回最终结果
     输入处理器在数据被接受到时执行，当数据收集完后调用ItemLoader.load_item()时再执行输出处理器，返回最终结果。
    """
 
    #文章标题
    source_title = scrapy.Field()
 
    title =  scrapy.Field()
    #文章URL
    docurl = scrapy.Field()
    #文章md5 URL
    project_doc_url = scrapy.Field()
    #大标题图片
    title_img = scrapy.Field(
        output_processor = MapCompose(return_value)
    )
    #图片存储路径
    img_path = scrapy.Field()
    #关键字
    key_words = scrapy.Field()
    #新闻类型 article
    newstype = scrapy.Field()
    #评论url
    commenturl = scrapy.Field()
    #文章作者
    news_editor = scrapy.Field(
        input_processor = MapCompose(get_editor)
    )
    #分段内容，图片名或者是内容
    news_cont = scrapy.Field(
        output_processor = MapCompose(return_value)
    )
    #文章内容源码
    content_org = scrapy.Field()
    #图片url
    # news_pic_url = scrapy.Field()
    #发表时间
    news_time = scrapy.Field(
        input_processor = MapCompose(return_time)
    )
    #文章来源
    news_source = scrapy.Field(
        input_processor = MapCompose(get_source)
    )
    down_img = scrapy.Field()

在Field定义中声明输入/输出处理器

优先级：

1. 在Item Loader中定义的field_in和field_out
2. Filed元数据(input_processor和output_processor关键字)
3. Item Loader中的默认的

Tips：一般来讲，将输入处理器定义在Item Loader的定义中field_in，然后将输出处理器定义在Field元数据中

内置的处理器

1. Identity 啥也不做
2. TakeFirst 返回第一个非空值，通常用作输出处理器
3. Join 将结果连起来，默认使用空格’ ‘
4. Compose 将函数链接起来形成管道流，产生最后的输出
5. MapCompose 跟上面的Compose类似，区别在于内部结果在函数中的传递方式.它的输入值是可迭代的，首先将第一个函数依次作用于所有值，产生新的可迭代输入，作为第二个函数的输入，最后生成的结果连起来返回最终值，一般用在输入处理器中。
6. SelectJmes 使用json路径来查询值并返回结果

4、pipleines设计

pipelines是用来处理item的，此例中用图片下载、json格式存储文件、数据存入数据库。数据库具体sql用*代替。

# -*- coding: utf-8 -*-
 
# Define your item pipelines here
#
# Don't forget to add your pipeline to the ITEM_PIPELINES setting
# See: http://doc.scrapy.org/en/latest/topics/item-pipeline.html
import codecs
# import hashlib
import json
# import random
# from scrapy.utils.python import to_bytes
 
import pymysql
# import time
from scrapy.pipelines.images import ImagesPipeline
from scrapy.exporters import JsonItemExporter
from scrapy.http import Request
 
from aticleSpider.until.common import get_md5
 
#默认方法
class ArticleSpiderPipeline(object):
    def process_item(self, item, spider):
        return item
 
#调用scrapy提供的json export导出json文件
class JsonExporterPipeline(object):
    #调用scrapy提供的json export导出json文件
    def __init__(self):
        self.file = open('articleexport.json', 'wb')
        self.exporter = JsonItemExporter(self.file, encoding="utf-8", ensure_ascii=False)
        self.exporter.start_exporting()
 
    def close_spider(self, spider):
        self.exporter.finish_exporting()
        self.file.close()
 
    def process_item(self, item, spider):
        self.exporter.export_item(item)
        return item
 
#北京163新闻数据入库操作
class Bj163MySqlPipeline(object):
    def __init__(self,db_parms):
 
        self.conn = pymysql.connect(**db_parms)
        self.cursor = self.conn.cursor()
 
    @classmethod
    def from_settings(cls,settings):
        db_parms = dict(
            host = settings['MYSQL_HOST'],
            user = settings['MYSQL_USER'],
            password = settings['MYSQL_PASSWORD'],
            database = settings['MYSQL_DBNAME'],
            charset='utf8'
        )
        # conn = pymysql.connect(**db_parms)
        return cls(db_parms)
 
    def process_item(self,item,spider):
        select_sql_find = """
            select id from toon_news_163 WHERE pageurl = %s;
        """
        self.cursor.execute(select_sql_find,(item['docurl']))
        odis = self.cursor.fetchall()
        if odis == ():
            insert_sql = """
                    insert into toon_news_163(*)
                    VALUES (%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s);
            """
            try:
                source_title = item['source_title']
            except:
                source_title = item['title']
            # print(item['news_time'],item['docurl'],item['news_editor'],source_title,item['key_words'],item['news_source'],
            #                                 item['title'],item['title_img'],item['content_org'],item['img_path'],item['docurl'])
            self.cursor.execute(insert_sql,('163网易北京',item['news_time'],item['docurl'],item['news_editor'],source_title,item['key_words'],item['news_source'],
                                            item['title'],item['title_img'],item['content_org'],item['img_path'],item['docurl']))
            self.conn.commit()
            select_sql = """
                    select max(id) FROM toon_news_163;
            """
            self.cursor.execute(select_sql)
            oidss = self.cursor.fetchall()
            max_id = oidss[0][0]
            # print(max_id)
            content = item['news_cont']
            for i in range(0,len(content)):
                if content[i]['type'] == 'pic':
                    pic_url = content[i]['content']
                else:
                    pic_url = ''
                insert_con_sql = """
                        insert into toon_news_content_163(*)
                        VALUES( %s,%s,%s,%s,%s,%s);
                """
                # print(str(max_id),content[i]['content'],content[i]['type'],str(i),0,pic_url,item['docurl'])
                self.cursor.execute(insert_con_sql,(str(max_id),content[i]['content'],content[i]['type'],str(i+1),0,item['docurl']))
                self.conn.commit()
            # return item
 
#json格式数据存储
class JsonWithEncodingPipeline(object):
    #自定义json文件的导出
    def __init__(self):
        self.file = codecs.open('article.json', 'w', encoding="utf-8")
    def process_item(self, item, spider):
        lines = json.dumps(dict(item), ensure_ascii=False) + "\n"
        self.file.write(lines)
        return item
    def spider_closed(self, spider):
        self.file.close()
 
#文章标题页图片下载
class ArticleImagePipeline(ImagesPipeline):
    #图片下载
    def file_path(self, request, response=None, info=None):
        ## start of deprecation warning block (can be removed in the future)
        def _warn():
            from scrapy.exceptions import ScrapyDeprecationWarning
            import warnings
            warnings.warn('ImagesPipeline.image_key(url) and file_key(url) methods are deprecated, '
                          'please use file_path(request, response=None, info=None) instead',
                          category=ScrapyDeprecationWarning, stacklevel=1)
 
        # check if called from image_key or file_key with url as first argument
        if not isinstance(request, Request):
            _warn()
            url = request
        else:
            url = request.url
 
        # detect if file_key() or image_key() methods have been overridden
        if not hasattr(self.file_key, '_base'):
            _warn()
            return self.file_key(url)
        elif not hasattr(self.image_key, '_base'):
            _warn()
            return self.image_key(url)
        ## end of deprecation warning block
 
        image_guid = get_md5(url)  # change to request.url after deprecation
        return '%s.jpg' % (image_guid)
 
    def item_completed(self, results, item, info):
        # if "title_img" in item:
        if "title_img" in item:
            img_path =''
            for ok,value in results:
                img_path = value['path']
            item['img_path'] = img_path
            # pass
        return item

5、setting设置

其中重要部分均已做注释，ITEM_PIPELINES参数为运行优先级，数值越小越优先

# -*- coding: utf-8 -*-
 
# Scrapy settings for aticleSpider 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
import os
 
BOT_NAME = 'aticleSpider'
 
SPIDER_MODULES = ['aticleSpider.spiders']
NEWSPIDER_MODULE = 'aticleSpider.spiders'
 
# Crawl responsibly by identifying yourself (and your website) on the user-agent
#USER_AGENT = 'aticleSpider (+http://www.yourdomain.com)'
 
# Obey robots.txt rules
ROBOTSTXT_OBEY = False
 
# Configure maximum concurrent requests performed by Scrapy (default: 16)
#CONCURRENT_REQUESTS = 32
 
# 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
#DOWNLOAD_DELAY = 3
# The download delay setting will honor only one of:
#CONCURRENT_REQUESTS_PER_DOMAIN = 16
#CONCURRENT_REQUESTS_PER_IP = 16
 
# Disable cookies (enabled by default)
#COOKIES_ENABLED = False
 
# Disable Telnet Console (enabled by default)
#TELNETCONSOLE_ENABLED = False
 
# 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',
#}
 
# Enable or disable spider middlewares
# See http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html
#SPIDER_MIDDLEWARES = {
#    'aticleSpider.middlewares.AticlespiderSpiderMiddleware': 543,
#}
 
# Enable or disable downloader middlewares
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {
#    'aticleSpider.middlewares.MyCustomDownloaderMiddleware': 543,
#}
 
# Enable or disable extensions
# See http://scrapy.readthedocs.org/en/latest/topics/extensions.html
#EXTENSIONS = {
#    'scrapy.extensions.telnet.TelnetConsole': None,
#}
 
# Configure item pipelines
# See http://scrapy.readthedocs.org/en/latest/topics/item-pipeline.html
ITEM_PIPELINES = {
   # 'aticleSpider.pipelines.ArticleSpiderPipeline': 100,
   'aticleSpider.pipelines.Bj163MySqlPipeline': 3,
   'aticleSpider.pipelines.ArticleImagePipeline':1,
 
}
 
IMAGES_URLS_FIELD ='title_img' #图片URL的item ,其值类型为list
project_dir = os.path.abspath(os.path.dirname(__file__))
IMAGES_STORE = os.path.join(project_dir, '163_news')  #图片存储位置
 
MYSQL_HOST = ''  #数据库host
MYSQL_USER = ''   #数据库user
MYSQL_DBNAME = '' #数据库database
MYSQL_PASSWORD = '' #数据库密码
 
# Enable and configure the AutoThrottle extension (disabled by default)
# See http://doc.scrapy.org/en/latest/topics/autothrottle.html
#AUTOTHROTTLE_ENABLED = True
# The initial download delay
#AUTOTHROTTLE_START_DELAY = 5
# The maximum download delay to be set in case of high latencies
#AUTOTHROTTLE_MAX_DELAY = 60
# The average number of requests Scrapy should be sending in parallel to
# each remote server
#AUTOTHROTTLE_TARGET_CONCURRENCY = 1.0
# Enable showing throttling stats for every response received:
#AUTOTHROTTLE_DEBUG = False
 
# Enable and configure HTTP caching (disabled by default)
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html#httpcache-middleware-settings
#HTTPCACHE_ENABLED = True
#HTTPCACHE_EXPIRATION_SECS = 0
#HTTPCACHE_DIR = 'httpcache'
#HTTPCACHE_IGNORE_HTTP_CODES = []
#HTTPCACHE_STORAGE = 'scrapy.extensions.httpcache.FilesystemCacheStorage'

6、运行scrapy项目

scrapy crawl 项目名称