1.aiohttp的简单使用(配合asyncio模块)
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import asyncio,aiohttp
async def fetch_async(url):
print(url)
async with aiohttp.request("GET",url) as r:
reponse = await r.text(encoding="utf-8") #或者直接await r.read()不编码,直接读取,适合于图像等无法编码文件
print(reponse)
tasks = [fetch_async('http://www.baidu.com/'), fetch_async('http://www.chouti.com/')]
event_loop = asyncio.get_event_loop()
results = event_loop.run_until_complete(asyncio.gather(*tasks))
event_loop.close()
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2.发起一个session请求
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import asyncio,aiohttp
async def fetch_async(url):
print(url)
async with aiohttp.ClientSession() as session: #协程嵌套,只需要处理最外层协程即可fetch_async
//代码效果参考:https://v.youku.com/v_show/id_XNjQwNjY0Mjc5Mg==.html
async with session.get(url) as resp:
print(resp.status)
print(await resp.text()) #因为这里使用到了await关键字,实现异步,所有他上面的函数体需要声明为异步async
tasks = [fetch_async('http://www.baidu.com/'), fetch_async('http://www.cnblogs.com/ssyfj/')]
event_loop = asyncio.get_event_loop()
results = event_loop.run_until_complete(asyncio.gather(*tasks))
event_loop.close()
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除了上面的get方法外,会话还支持post,put,delete....等
session.put('http://httpbin.org/put', data=b'data')
session.delete('http://httpbin.org/delete')
session.head('http://httpbin.org/get')
session.options('http://httpbin.org/get')
session.patch('http://httpbin.org/patch', data=b'data')
不要为每次的连接都创建一次session,一般情况下只需要创建一个session,然后使用这个session执行所有的请求。
每个session对象,内部包含了一个连接池,并且将会保持连接和连接复用(默认开启)可以加快整体的性能。
3.在url中传递参数(其实与requests模块使用大致相同)
只需要将参数字典,传入params参数中即可
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import asyncio,aiohttp
async def func1(url,params):
async with aiohttp.ClientSession() as session:
async with session.get(url,params=params) as r:
print(r.url)
print(await r.read())
tasks = [func1('https://www.ckook.com/forum.php',{"gid":6}),]
event_loop = asyncio.get_event_loop()
results = event_loop.run_until_complete(asyncio.gather(*tasks))
event_loop.close()
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4.获取响应内容(由于获取响应内容是一个阻塞耗时过程,所以我们使用await实现协程切换)
(1)使用text()方法
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async def func1(url,params):
async with aiohttp.ClientSession() as session:
async with session.get(url,params=params) as r:
print(r.url)
print(r.charset) #查看默认编码为utf-8
print(await r.text())
//代码效果参考:https://v.youku.com/v_show/id_XNjQwNjc4ODQxMg==.html
不编码,则是使用默认编码 使用encoding指定编码
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(2)使用read()方法,不进行编码,为字节形式
async def func1(url,params):
async with aiohttp.ClientSession() as session:
async with session.get(url,params=params) as r:
print(r.url)
print(await r.read())
(3)注意:text(),read()方法是把整个响应体读入内存,如果你是获取大量的数据,请考虑使用”字节流“(StreamResponse)
5.特殊响应内容json(和上面一样)
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async def func1(url,params):
async with aiohttp.ClientSession() as session:
async with session.get(url,params=params) as r:
print(r.url)
print(r.charset)
print(await r.json()) #可以设置编码,设置处理函数
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6.字节流形式获取数据(不像text,read一次获取所有数据)
注意:我们获取的session.get()是Response对象,他继承于StreamResponse
async def func1(url,params):
async with aiohttp.ClientSession() as session:
async with session.get(url,params=params) as r:
print(await r.content.read(10)) #读取前10字节
下面字节流形式读取数据,保存文件
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async def func1(url,params,filename):
async with aiohttp.ClientSession() as session:
async with session.get(url,params=params) as r:
with open(filename,"wb") as fp:
while True:
chunk = await r.content.read(10)
if not chunk:
break
fp.write(chunk)
tasks = [func1('https://www.ckook.com/forum.php',{"gid":6},"1.html"),]