Scrapy 笔记（二）

一个scrapy爬虫知乎项目的笔记

1、通过命令创建项目

scrapy startproject zhihu
cd zhihu
scrapy genspider zhihu www.zhihu.com（临时的项目，非正式）

直接通过scrapy crawl zhihu启动爬虫会看到如下错误：500、501之类服务器错误。

解决：在setting.py 中为爬虫添加User-Agent

# Override the default request headers:
DEFAULT_REQUEST_HEADERS = {
    'User-Agent':"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_5)AppleWebKit/537.36 (KHTML, like Gecko) Chrome/59.0.3071.115 Safari/537.36",
    'authorization':'oauth c3cef7c66a1843f8b3a9e6a1e3160e20'
}

继续尝试后出现401，错误

解决：分析浏览器行为，得到需要添加 header:'authorization':'oauth c3cef7c66a1843f8b3a9e6a1e3160e20'
尝试后成功访问到知乎。

2、书写项目中的所需数据item

class UserItem(scrapy.Item):
    # define the fields for your item here like:
    # name = scrapy.Field()
    name = scrapy.Field()
    headline = scrapy.Field()
    url_token = scrapy.Field()

3、midwares暂时不需要修改

def spider_opened(self, spider):
　　spider.logger.info('Spider opened: %s' % spider.name)

4、主要代码zhihuspider书写

# -*- coding: utf-8 -*-
import json
import scrapy
from scrapy import Spider,Request
from zhihu.items import UserItem

class ZhihuSpider(scrapy.Spider):
    name = "zhihu"
    allowed_domains = ["www.zhihu.com"]
    start_urls = ['http://www.zhihu.com/']
    #这里定义一个start_user存储我们找的大V账号
    #start_user = "-LKs-"
    start_user = 'undo-59-76'

    #这里把查询的参数单独存储为user_query,user_url存储的为查询用户信息的url地址
    user_url = "https://www.zhihu.com/api/v4/members/{user}?include={include}"
    user_query = "locations,employments,gender,educations,business,voteup_count,thanked_Count,follower_count,following_count,cover_url,following_topic_count,following_question_count,following_favlists_count,following_columns_count,avatar_hue,answer_count,articles_count,pins_count,question_count,columns_count,commercial_question_count,favorite_count,favorited_count,logs_count,marked_answers_count,marked_answers_text,message_thread_token,account_status,is_active,is_bind_phone,is_force_renamed,is_bind_sina,is_privacy_protected,sina_weibo_url,sina_weibo_name,show_sina_weibo,is_blocking,is_blocked,is_following,is_followed,mutual_followees_count,vote_to_count,vote_from_count,thank_to_count,thank_from_count,thanked_count,description,hosted_live_count,participated_live_count,allow_message,industry_category,org_name,org_homepage,badge[?(type=best_answerer)].topics"

    #follows_url存储的为关注列表的url地址,fllows_query存储的为查询参数。这里涉及到offset和limit是关于翻页的参数，0，20表示第一页
    follows_url = "https://www.zhihu.com/api/v4/members/{user}/followees?include={include}&offset={offset}&limit={limit}"
    follows_query = "data%5B*%5D.answer_count%2Carticles_count%2Cgender%2Cfollower_count%2Cis_followed%2Cis_following%2Cbadge%5B%3F(type%3Dbest_answerer)%5D.topics"

    #followers_url是获取粉丝列表信息的url地址，followers_query存储的为查询参数。
    followers_url = "https://www.zhihu.com/api/v4/members/{user}/followers?include={include}&offset={offset}&limit={limit}"
    followers_query = "data%5B*%5D.answer_count%2Carticles_count%2Cgender%2Cfollower_count%2Cis_followed%2Cis_following%2Cbadge%5B%3F(type%3Dbest_answerer)%5D.topics"

    def start_requests(self):
        '''
        start_requests方法，分别请求了用户查询的url和关注列表的查询以及粉丝列表信息查询
        :return:
        '''

        yield Request(self.user_url.format(user=self.start_user,include=self.user_query),callback=self.parse_user)
        yield Request(self.follows_url.format(user=self.start_user,include=self.follows_query,offset=0,limit=20),callback=self.parse_follows)
        yield Request(self.followers_url.format(user=self.start_user,include=self.followers_query,offset=0,limit=20),callback=self.parse_followers)

    def parse_user(self, response):
        '''
        因为返回的是json格式的数据，所以这里直接通过json.loads获取结果
        :param response:
        :return:
        '''
        result = json.loads(response.text)
        item = UserItem()
        #这里循环判断获取的字段是否在自己定义的字段中，然后进行赋值
        for field in item.fields:
            if field in result.keys():
                item[field] = result.get(field)
                print(item[field])

        #这里在返回item的同时返回Request请求，继续递归拿关注用户信息的用户获取他们的关注列表
        yield item
        yield Request(self.follows_url.format(user = result.get("url_token"),include=self.follows_query,offset=0,limit=20),callback=self.parse_follows)
        yield Request(self.followers_url.format(user = result.get("url_token"),include=self.followers_query,offset=0,limit=20),callback=self.parse_followers)

    def parse_follows(self, response):
        '''
        查询关注的callback函数
        '''
        results = json.loads(response.text)

        if 'data' in results.keys():
            for result in results.get('data'):
                yield Request(self.user_url.format(user = result.get("url_token"),include=self.user_query),callback=self.parse_user)

        #这里判断page是否存在并且判断page里的参数is_end判断是否为False，如果为False表示不是最后一页，否则则是最后一页
        if 'paging' in results.keys() and results.get('is_end') == False:
            next_page = results.get('paging').get("next")
            #获取下一页的地址然后通过yield继续返回Request请求，继续请求自己再次获取下页中的信息
            yield Request(next_page,self.parse_follows)

    def parse_followers(self, response):
        '''
        这里其实和关乎列表的处理方法是一样的
        用户粉丝列表的解析，这里返回的也是json数据 这里有两个字段data和paging，其中page是分页信息
        '''
        results = json.loads(response.text)

        if 'data' in results.keys():
            for result in results.get('data'):
                yield Request(self.user_url.format(user = result.get("url_token"),include=self.user_query),callback=self.parse_user)

        #这里判断page是否存在并且判断page里的参数is_end判断是否为False，如果为False表示不是最后一页，否则则是最后一页
        if 'paging' in results.keys() and results.get('paging').get('is_end') == False:
            next_page = results.get('paging').get("next")
            #获取下一页的地址然后通过yield继续返回Request请求，继续请求自己再次获取下页中的信息
            yield Request(next_page,self.parse_followers)

Hide

# -*- coding: utf-8 -*-
import json
import scrapy
from scrapy import Spider,Request
from zhihu.items import UserItem

class ZhihuSpider(scrapy.Spider):
    name = "zhihu"
    allowed_domains = ["www.zhihu.com"]
    start_urls = ['http://www.zhihu.com/']

        yield Request(url,callback=self.parse_user)
        yield Request(url,callback=self.parse_follows)
        yield Request(url,callback=self.parse_followers)

    def parse_user(self, response):
        result = json.loads(response.text)
        item = UserItem()
        #这里循环判断获取的字段是否在自己定义的字段中，然后进行赋值
        for field in item.fields:
            if field in result.keys():
                item[field] = result.get(field)
                print(item[field])

        #这里在返回item的同时返回Request请求，继续递归拿关注用户信息的用户获取他们的关注列表
        yield item
        yield Request(url,callback=self.parse_follows)
        yield Request(url,callback=self.parse_followers)

    def parse_follows(self, response):
        '''
        查询关注的callback函数
        '''
        results = json.loads(response.text)

        if 'data' in results.keys():
            for result in results.get('data'):
                yield Request(self.user_url.format(user = result.get("url_token"),include=self.user_query),callback=self.parse_user)

        #这里判断page是否存在并且判断page里的参数is_end判断是否为False，如果为False表示不是最后一页，否则则是最后一页
        if 'paging' in results.keys() and results.get('is_end') == False:
            next_page = results.get('paging').get("next")
            #获取下一页的地址然后通过yield继续返回Request请求，继续请求自己再次获取下页中的信息
            yield Request(next_page,self.parse_follows)

5、存储爬取到的数据

在pipline中处理爬取到的内容

import json
import pymysql
from scrapy.exceptions import DropItem

#存入json文件pipeline
class JsonFilePipeline(object):

    def __init__(self):
        self.file = open('items.jl', 'w',encoding='utf-8')

    def process_item(self, item, spider):
        line = json.dumps(dict(item),ensure_ascii=False) + "\n"

        #print('hello')
        print(line)
        self.file.write(line)
        return item
#去重pipeline
class DuplicatesPipeline(object):

    def __init__(self):
        self.ids_seen = set()

    def process_item(self, item, spider):
        if item['url_token'] in self.ids_seen:
            raise DropItem("Duplicate item found: %s" % item)
        else:
            self.ids_seen.add(item['url_token'])
            return item

#存入mysql数据库pipeline
class MysqlPipeline(object):
    MysqlHandle = ''
    Cusor = ''
    #def __init__(self):
    #打开爬虫时操作
    def open_spider(self, spider):
        print('打开爬虫')
        print('连接sql')
        self.MysqlHandle = self.dbHandle()
        self.Cusor = self.MysqlHandle.cursor()

    def close_spider(self, spider):
        print('关闭爬虫')
        print('关闭sql')
        #关闭游标
        self.Cusor.close()
        #关闭连接fetch
        self.MysqlHandle.close()

    def dbHandle(self):
        conn = pymysql.connect(
            host='localhost',
            user='root',
            passwd='passwd',
            db = "databases",
            charset='utf8',
            use_unicode=False
        )
        return conn

    def process_item(self, item, spider):
        dbObject = self.MysqlHandle
        cursor = self.Cusor
        sql = 'insert ignore into zhihu(url_token,name,headline) values (%s,%s,%s)'

        try:
            cursor.execute(sql,(item['url_token'],item['name'],item['headline']))
            dbObject.commit()
        except Exception as e:
            print(e)
            dbObject.rollback()

        return item

pipeline.py

需要在setting中设置的内容

# Configure item pipelines
# See http://scrapy.readthedocs.org/en/latest/topics/item-pipeline.html
ITEM_PIPELINES = {
    #保存在文件中
    #'zhihu.pipelines.JsonFilePipeline': 300
    #保存在mysql数据库中
    'zhihu.pipelines.MysqlPipeline': 800,
    #去重
    'zhihu.pipelines.DuplicatesPipeline':300
}

6、setting中可设置的选项（待添加）

　　#log change
　　LOG_ENABLED = False
　　#LOG_LEVEL = 'ERROR'
　　#LOG_FILE = 'log.txt'

7、scrapy的增量爬重（暂停的开启与关闭）

　　怎么使用

要启用一个爬虫的持久化，运行以下命令:

scrapy crawl somespider -s JOBDIR=crawls/somespider-1

然后，你就能在任何时候安全地停止爬虫(按Ctrl-C或者发送一个信号)。恢复这个爬虫也是同样的命令:

scrapy crawl somespider -s JOBDIR=crawls/somespider-1