python3 协程 返回值_python asyncio 获取协程返回值和使用callback
1. 获取协程返回值，实质就是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")) # 相当于开启一个future
loop.run_until_complete(get_future) # 事件循环
print(get_future.result()) # 获取结果
2. 使用loop自带的create task， 获取返回值
# 获取协程的返回值
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地方的内容一运行完，就会运行callback
# 获取协程的返回值
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): #这里默认传入一个future对象
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这个模块向callback函数中传入值
# 获取协程的返回值
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): # 传入值的时候，future必须在最后一个
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())