055 Python语法之异步IO-Async

Async初识

# Author：Luo
import asyncio
import threading
import random

@asyncio.coroutine  # 说明符，可以当做注解来看
def hello():
    print("Hello Up", threading.current_thread().getName())
    yield from asyncio.sleep(random.randint(1,3))   # 一个阻塞了会运行另一个
    print("Hello down",threading.current_thread().getName())

loop = asyncio.get_event_loop() # 异步任务
tasks=[hello(),hello(),hello()] # 三个任务
loop.run_until_complete(asyncio.wait(tasks))    # 等待运行完成任务
loop.close()    # 关闭任务

异步下载

# Author：Luo
import asyncio

# yield from 等效于await

def download(url):
    print("download", url)
    connect = asyncio.open_connection(url, 80)  # 打开网页服务器端口
    reader, writer = yield from connect  # 等待链接打开成功
    header = "GET / HTTP/1.0\r\nHost:%s\r\n\r\n" % url  # 生成访问头
    writer.write(header.encode("utf-8"))
    yield from writer.drain()  # 等待上面的header写完
    while True:
        line = yield from reader.readline()  # 读取完成
        if line == b"\r\n":
            break
        print("%s header >%s" % (url, line.decode("utf-8")))  # 打印下信息
    writer.close()


loop = asyncio.get_event_loop()  # 协程异步循环
tasks = [download(url=url) for url in ["www.1000phone.com",
                                       "www.mobiletrain.org"]]  # 生成任务列表
loop.run_until_complete(asyncio.wait(tasks))  # 等待任务完成
loop.close()

异步下载Async

# Author：Luo
import asyncio

# yield from 等效于await

async def download(url):
    print("download", url)
    connect = asyncio.open_connection(url, 80)  # 打开网页服务器端口
    reader, writer = await connect  # 等待链接打开成功
    header = "GET / HTTP/1.0\r\nHost:%s\r\n\r\n" % url  # 生成访问头
    writer.write(header.encode("utf-8"))
    await writer.drain()  # 等待上面的header写完
    while True:
        line = await reader.readline()  # 读取完成
        if line == b"\r\n":
            break
        print("%s header >%s" % (url, line.decode("utf-8")))  # 打印下信息
    writer.close()


loop = asyncio.get_event_loop()  # 协程异步循环
tasks = [download(url=url) for url in ["www.1000phone.com",
                                       "www.mobiletrain.org"]]  # 生成任务列表
loop.run_until_complete(asyncio.wait(tasks))  # 等待任务完成
loop.close()