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：
- 在Item Loader中定义的
field_in和field_out - Filed元数据(
input_processor和output_processor关键字) - 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
Identity啥也不做TakeFirst返回第一个非空值，通常用作输出处理器Join将结果连起来，默认使用空格’ ‘Compose将函数链接起来形成管道流，产生最后的输出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。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
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