aiohttp 支持异步的网络请求模块

　　通常在进行网络数据采集时候我们会用到requests,urllib等模块,但是这些模块在使用中并不支持异步,所以今天我们介绍一个支持异步网络请求的模块aiohttp.

首先我们使用flask简单的搭一个服务器:

from flask import Flask

app = Flask(__name__)

@app.route('/xiaohua')
def xiaohua():
    return 'i am xiaohua'

@app.route('/xiaohuang')
def xiaohuang():
    return 'i am xiaohuang'

@app.route('/xiaoming')
def xiaoming():
    return 'i am xiaoming'

if __name__ == '__main__':
    app.run()　　

下面是通过aiohttp进行的异步访问 :

import aiohttp
import time
import asyncio

async def get_page(url):               #加async关键字,使函数返回一个协程对象
    async with aiohttp.ClientSession() as session:  #创建ClientSession对象
        async with await session.get(url=url) as response:  #将url传入get方法并赋值到response
            page_text = await response.text()    #遇IO手动挂起
            print(page_text)
start = time.time()
urls = [
    'http://127.0.0.1:5000/xiaohua',
    'http://127.0.0.1:5000/xiaoming',
    'http://127.0.0.1:5000/xiaohuang',
    'http://127.0.0.1:5000/xiaohua',
    'http://127.0.0.1:5000/xiaoming',
    'http://127.0.0.1:5000/xiaohuang',
    'http://127.0.0.1:5000/xiaohua',
    'http://127.0.0.1:5000/xiaoming',
    'http://127.0.0.1:5000/xiaohuang',

]
tasks = []
loop = asyncio.get_event_loop()    #创建事件循环
for url in urls:
    c = get_page(url)     #接收协程对象
    task = asyncio.ensure_future(c)   #对协程对象进一步封装成future
    tasks.append(task)
loop.run_until_complete(asyncio.wait(tasks))   #将多个任务对象对应的列表注册到事件循环中,需使用asyncio.wait进行逐一取值
print('总耗时：',time.time()-start)

结果 :

i am xiaoming
i am xiaoming
i am xiaohuang
i am xiaoming
i am xiaohua
i am xiaohuang
i am xiaohuang
i am xiaohua
i am xiaohua
总耗时： 0.018949031829833984

　　从结果可以看出,通过使用aiohttp模块,访问实现了异步访问,大大提高了效率.