python链家网二手房异步爬虫asyncio+aiohttp+aiomysql异步存入数据库

python链家网二手房异步IO爬虫asyncio+aiohttp+aiomysql异步存入数据库

很多小伙伴初学python时都会学习到爬虫，刚入门时会使用requests、urllib这些同步的库进行单线程爬虫，速度是比较慢的，后学会用scrapy框架进行爬虫，速度很快，原因是scrapy是基于twisted多线程异步IO框架。
本例使用的asyncio也是一个异步IO框架，在python3.5以后加入了协程的关键字async，能够将协程和生成器区分开来，更加方便使用协程。
经过测试，平均1秒可以爬取30个详情页信息
可以使用asyncio.Semaphore来控制并发数，达到限速的效果

# -*- coding: utf-8 -*-
"""
    :author: KK
    :url: http://github.com/PythonerKK
    :copyright: © 2019 KK <[email protected]>
"""
import asyncio
import re
import aiohttp
from pyquery import PyQuery
import aiomysql
from lxml import etree

pool = ''
#sem = asyncio.Semaphore(4)  用来控制并发数，不指定会全速运行
stop = False
headers = {
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.100 Safari/537.36'
}
MAX_PAGE = 10
TABLE_NAME = 'data'  #数据表名
city = 'zh'  #城市简写
url = 'https://{}.lianjia.com/ershoufang/pg{}/'  #url地址拼接
urls = []  #所有页的url列表
links_detail = set()  #爬取中的详情页链接的集合
crawled_links_detail = set()  #爬取完成的链接集合，方便去重


async def fetch(url, session):
    '''
    aiohttp获取网页源码
    '''
    # async with sem:
    try:
        async with session.get(url, headers=headers, verify_ssl=False) as resp:
            if resp.status in [200, 201]:
                data = await resp.text()
                return data
    except Exception as e:
        print(e)

def extract_links(source):
    '''
    提取出详情页的链接
    '''
    pq = PyQuery(source)
    for link in pq.items("a"):
        _url = link.attr("href")
        if _url and re.match('https://.*?/\d+.html', _url) and _url.find('{}.lianjia.com'.format(city)):
            links_detail.add(_url)

    print(links_detail)

def extract_elements(source):
    '''
    提取出详情页里面的详情内容
    '''
    try:
        dom = etree.HTML(source)
        id = dom.xpath('//link[@rel="canonical"]/@href')[0]
        title = dom.xpath('//title/text()')[0]
        price = dom.xpath('//span[@class="unitPriceValue"]/text()')[0]
        information = dict(re.compile('
(.*?)(.*?)
').findall(source))
        information.update(title=title, price=price, url=id)
        print(information)
        asyncio.ensure_future(save_to_database(information, pool=pool))

    except Exception as e:
        print('解析详情页出错！')
        pass

async def save_to_database(information, pool):
    '''
    使用异步IO方式保存数据到mysql中
    注：如果不存在数据表，则创建对应的表
    '''
    COLstr = ''  # 列的字段
    ROWstr = ''  # 行字段
    ColumnStyle = ' VARCHAR(255)'
    for key in information.keys():
        COLstr = COLstr + ' ' + key + ColumnStyle + ','
        ROWstr = (ROWstr + '"%s"' + ',') % (information[key])
    # 异步IO方式插入数据库
    async with pool.acquire() as conn:
        async with conn.cursor() as cur:
            try:
                await cur.execute("SELECT * FROM  %s" % (TABLE_NAME))
                await cur.execute("INSERT INTO %s VALUES (%s)"%(TABLE_NAME, ROWstr[:-1]))
                print('插入数据成功')
            except aiomysql.Error as e:
                await cur.execute("CREATE TABLE %s (%s)" % (TABLE_NAME, COLstr[:-1]))
                await cur.execute("INSERT INTO %s VALUES (%s)" % (TABLE_NAME, ROWstr[:-1]))
            except aiomysql.Error as e:
                print('mysql error %d: %s' % (e.args[0], e.args[1]))

async def handle_elements(link, session):
    '''
    获取详情页的内容并解析
    '''
    print('开始获取: {}'.format(link))
    source = await fetch(link, session)
    #添加到已爬取的集合中
    crawled_links_detail.add(link)
    extract_elements(source)

async def consumer():
    '''
    消耗未爬取的链接
    '''
    async with aiohttp.ClientSession() as session:
        while not stop:
            if len(urls) != 0:
                _url = urls.pop()
                source = await fetch(_url, session)
                print(_url)
                extract_links(source)

            if len(links_detail) == 0:
                print('目前没有待爬取的链接')
                await asyncio.sleep(2)
                continue

            link = links_detail.pop()
            if link not in crawled_links_detail:
                asyncio.ensure_future(handle_elements(link, session))

async def main(loop):
    global pool
    pool = await aiomysql.create_pool(host='127.0.0.1', port=3306,
                                      user='root', password='xxxxxx',
                                      db='aiomysql_lianjia', loop=loop, charset='utf8',
                                      autocommit=True)

    for i in range(1, MAX_PAGE):
        urls.append(url.format(city, str(i)))
    print('爬取总页数：{} 任务开始...'.format(str(MAX_PAGE)))
    asyncio.ensure_future(consumer())

if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    asyncio.ensure_future(main(loop))
    loop.run_forever()