python asyncio 獲取協程返回值和使用callback

1. 獲取協程返回值，實質就是future中的task

import asyncio
import time
async def get_html(url):
    print("start get url")
    await asyncio.sleep(2)
    return "bobby"

def callback(url, future):
    print(url)
    print("send email to bobby")

if __name__ == "__main__":
    start_time = time.time()
    loop = asyncio.get_event_loop()
    get_future = asyncio.ensure_future(get_html("http://www.imooc.com")) # 至關於開啓一個future
    loop.run_until_complete(get_future) # 事件循環
    print(get_future.result()) # 獲取結果

 

 

2. 使用loop自帶的create task， 獲取返回值

# 獲取協程的返回值
import asyncio
import time
from functools import partial
async def get_html(url):
    print("start get url")
    await asyncio.sleep(2)
    return "bobby"

def callback(url, future):
    print(url)
    print("send email to bobby")

if __name__ == "__main__":
    start_time = time.time()
    loop = asyncio.get_event_loop()
    task = loop.create_task(get_html("http://www.imooc.com"))
    loop.run_until_complete(task)
    print(task.result())

 

 

3. 使用callback,只要await地方的內容一運行完，就會運行callback

# 獲取協程的返回值
import asyncio
import time
from functools import partial
async def get_html(url):
    print("start get url")
    await asyncio.sleep(2)
    return "bobby"

def callback(future): #這裏默認傳入一個future對象
    print("send email to bobby")

if __name__ == "__main__":
    start_time = time.time()
    loop = asyncio.get_event_loop()
    task = loop.create_task(get_html("http://www.imooc.com"))
    task.add_done_callback(callback)
    loop.run_until_complete(task)
    print(task.result())

 

 

使用partial這個模塊向callback函數中傳入值

# 獲取協程的返回值
import asyncio
import time
from functools import partial
async def get_html(url):
    print("start get url")
    await asyncio.sleep(2)
    return "bobby"

def callback(future):
    print("send email to bobby")

def callback1(url, future): # 傳入值的時候，future必須在最後一個
    print(url)
    print("send email to bobby")
if __name__ == "__main__":
    start_time = time.time()
    loop = asyncio.get_event_loop()
    task = loop.create_task(get_html("http://www.imooc.com"))
    task.add_done_callback(partial(callback1, "http://www.imooc.com"))
    loop.run_until_complete(task)
    print(task.result())