本帖最后由 天空宫阙 于 2020-12-5 22:15 编辑
微博图片链接的爬取还是用的requests在weibo_photo.py文件（需要加入自己登录后的cookie），最终生成result.json,不是重点不多讲。
用asyncio + aiohttp异步下载result.json中jpg格式的图片在weibo_photo_dl.py
安装完依赖pip3 install -r requirements.txt
后可以直接运行weibo_photo_dl.py
weibo_photo_dl.py代码
[Python] 纯文本查看 复制代码 import aiohttp
import asyncio
import aiofiles
import json
import os
import time
from aiohttp import client_exceptions
from MYretry import *
loop = asyncio.get_event_loop()
class Async_download:
def __init__(self):
super().__init__()
self.CONCURRENCY = 5
self.session = None
self.semaphore = asyncio.Semaphore(self.CONCURRENCY)
self.save_path = 'result'
""" 利用python装饰器实现请求的重试 """
@MYretry(client_exceptions.ServerDisconnectedError)
async def request(self, url):
async with self.semaphore:
# try:
print('getting', url)
# 添加ssl=False 防止SSLCertVerificationError
async with self.session.get(url,ssl=False) as response:
await asyncio.sleep(1)
return await response.read()
# except client_exceptions.ServerDisconnectedError:
# print('ServerDisconnectedError occurred while scraping ',url)
def save_pic(self, name, content):
# 同步的写入文件
name = os.path.join(self.save_path, name)
with open(name, 'wb') as f:
f.write(content)
f.close()
async def save_pic2(self, name, content):
""" 未知是否异步 """
name = os.path.join(self.save_path, name)
async with aiofiles.open(name, mode='wb') as f:
await f.write(content)
def get_url_list(self, path):
url_list = []
with open(path, 'r', encoding='utf-8') as f:
res_json = json.loads(f.read())
for card in res_json:
if card['card_type'] == 47:
for pic in card['pics']:
if pic['pic_big'][-4:] == '.gif':
continue
url_list.append(pic['pic_big'])
return url_list
async def download_one(self, url, name):
name = str(name).zfill(4)+'.jpg'
content = await self.request(url)
print('saved', name)
if content:
await self.save_pic2(name, content)
async def main(self, url_list):
self.session = aiohttp.ClientSession()
# 添加任务一行写法
tasks = [asyncio.ensure_future(self.download_one(
url_list[i], i)) for i in range(len(url_list))]
# tasks = []
# for i in range(len(url_list)):
# tasks.append(asyncio.ensure_future(self.download_one(url_list[i],i)))
await asyncio.gather(*tasks)
await self.session.close()
def run(self):
if not os.path.exists(self.save_path):
os.makedirs(self.save_path)
url_list = self.get_url_list('result.json')
loop.run_until_complete(self.main(url_list))
if __name__ == "__main__":
start_time = time.time()
spider = Async_download()
spider.run()
print('cost', time.time()-start_time)
MYretry.py对异常进行了简单的处理利用了装饰器
MYretry.py代码
[Python] 纯文本查看 复制代码 import logging
from functools import wraps
import asyncio
log = logging.getLogger(__name__)
def MYretry(*exceptions, retries=3, cooldown=1, verbose=True):
# [url=https://www.cnblogs.com/killianxu/p/9821414.html]https://www.cnblogs.com/killianxu/p/9821414.html[/url]
"""Decorate an async function to execute it a few times before giving up.
Hopes that problem is resolved by another side shortly.
Args:
exceptions (Tuple[Exception]) : The exceptions expected during function execution
retries (int): Number of retries of function execution.
cooldown (int): Seconds to wait before retry.
verbose (bool): Specifies if we should log about not successful attempts.
"""
def wrap(func):
@wraps(func)
async def inner(*args, **kwargs):
retries_count = 0
while True:
try:
result = await func(*args, **kwargs)
except exceptions as err:
retries_count += 1
message = "Exception during {} execution. " \
"{} of {} retries attempted".format(func, retries_count, retries)
if retries_count > retries:
verbose and log.exception(message)
# raise RetryExhaustedError(func.__qualname__, args, kwargs) from err
raise Exception('reached max trying times')
else:
verbose and log.warning(message)
if cooldown:
await asyncio.sleep(cooldown)
else:
return result
return inner
return wrap
问题
1.只对client_exceptions.ServerDisconnectedError进行了处理
若在请求中出现其他异常可以添加到
@MYretry(client_exceptions.ServerDisconnectedError,otherexception)
2.不谈weibo_photo.py获取链接是同步方式，
单是weibo_photo_dl.py也有一种异步和同步代码杂糅的感觉，不知aiofiles这样用是否可以实现异步的文件写入
恳请大佬指点
完整代码下载链接
https://www.lanzouj.com/ic1tjyf
代码不具备通用性，当前的功能是批量下载鞠婧祎的微博相册图片（jpg），
如需采集其他用户需要改weibo_photo.py得到新的result.json文件
效果
经过简单的异常处理没有遗漏的
并发数CONCURRENCY为5我家的垃圾网络用了400s下载了1500多张图
（非并发情况下等一张图片的响应就要超过1s）可以说协程的效果还不错
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发表于 2020-4-28 22:49
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发表于 2020-4-29 12:07
