python链家网高并发异步爬虫asyncio+aiohttp+aiomysql异步存入数据

矫情吗；* 2022-01-09 08:15 359阅读 0赞

## python链家网二手房异步IO爬虫，使用asyncio、aiohttp和aiomysql ##

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

![1579698-20190305120650251-1695379729.png][]  
![1579698-20190305120658440-746826969.png][]

# -*- coding: utf-8 -*-
    """
        :author: KK
        :url: http://github.com/PythonerKK
        :copyright: © 2019 KK <705555262@qq.com.com>
    """
    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('<li><span class="label">(.*?)</span>(.*?)</li>').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()

转载于:https://www.cnblogs.com/PyKK2019/p/aiohttp\_spider.html

[1579698-20190305120650251-1695379729.png]: /images/20220109/27ffabecfb2a4bb0b46cac5e92a28674.png
[1579698-20190305120658440-746826969.png]: /images/20220109/3aec85ea43ce40f4aa290fc313e5c744.png