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Python grequests模块
使用场景：
1) 爬虫设置ip代理池时验证ip是否有效
2）进行压测时，进行批量请求等等场景
grequests 利用 requests和gevent库，做了一个简单封装，使用起来非常方便。
grequests.map(requests, stream=False, size=None, exception_handler=None, gtimeout=None)
另外，由于grequests底层使用的是requests，因此它支持
GET，OPTIONS， HEAD， POST， PUT， DELETE 等各种http method
所以以下的任务请求都是支持的
grequests.post(url, json={“name”:“zhangsan”})
grequests.delete(url)
代码如下:
import grequests
urls = [
'http://www.baidu.com',
'http://www.qq.com',
'http://www.163.com',
'http://www.zhihu.com',
'http://www.toutiao.com',
'http://www.douban.com'
]
rs = (grequests.get(u) for u in urls)
print(grequests.map(rs)) # [<Response [200]>, None, <Response [200]>, None, None, <Response [418]>]
def exception_handler(request, exception):
print("Request failed")
reqs = [
grequests.get('http://httpbin.org/delay/1', timeout=0.001),
grequests.get('http://fakedomain/'),
grequests.get('http://httpbin.org/status/500')
]
print(grequests.map(reqs, exception_handler=exception_handler))
实际操作中，也可以自定义返回的结果
修改grequests源码文件:
例如:
新增extract_item() 函数合修改map()函数
def extract_item(request):
"""
提取request的内容
:param request:
:return:
"""
item = dict()
item["url"] = request.url
item["text"] = request.response.text or ""
item["status_code"] = request.response.status_code or 0
return item
def map(requests, stream=False, size=None, exception_handler=None, gtimeout=None):
"""Concurrently converts a list of Requests to Responses.
:param requests: a collection of Request objects.
:param stream: If True, the content will not be downloaded immediately.
:param size: Specifies the number of requests to make at a time. If None, no throttling occurs.
:param exception_handler: Callback function, called when exception occured. Params: Request, Exception
:param gtimeout: Gevent joinall timeout in seconds. (Note: unrelated to requests timeout)
"""
requests = list(requests)
pool = Pool(size) if size else None
jobs = [send(r, pool, stream=stream) for r in requests]
gevent.joinall(jobs, timeout=gtimeout)
ret = []
for request in requests:
if request.response is not None:
ret.append(extract_item(request))
elif exception_handler and hasattr(request, 'exception'):
ret.append(exception_handler(request, request.exception))
else:
ret.append(None)
yield ret
可以直接调用:
import grequests urls = [ 'http://www.baidu.com', 'http://www.qq.com', 'http://www.163.com', 'http://www.zhihu.com', 'http://www.toutiao.com', 'http://www.douban.com' ] rs = (grequests.get(u) for u in urls) response_list = grequests.map(rs, gtimeout=10) for response in next(response_list): print(response)
支持事件钩子
def print_url(r, *args, **kwargs):
print(r.url)
url = “http://www.baidu.com”
res = requests.get(url, hooks={“response”: print_url})
tasks = []
req = grequests.get(url, callback=print_url)
tasks.append(req)
ress = grequests.map(tasks)
print(ress)
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持码农之家。
