import asyncio
import time


async def _task():
    print(f"{time.strftime('%H:%M:%S')} task 开始 ")
    time.sleep(2)
    print(f"{time.strftime('%H:%M:%S')} task 结束")
    return "运行结束"


def callback(task):
    print(f"{time.strftime('%H:%M:%S')} 回调函数开始运行")
    print(f"状态：{task.result()}")


coroutine = _task()
print(f"{time.strftime('%H:%M:%S')} 产生协程对象 {coroutine},函数并未被调用")
task = asyncio.ensure_future(coroutine)  # 返回task对象
task.add_done_callback(callback)  # 为task增加一个回调任务
loop = asyncio.get_event_loop()
print(f"{time.strftime('%H:%M:%S')} 开始调用协程任务")
start = time.time()
loop.run_until_complete(task)
end = time.time()
print(f"{time.strftime('%H:%M:%S')} 结束调用协程任务, 耗时{end - start} 秒")