Python 15 爬虫（一）

https://www.cnblogs.com/wupeiqi/articles/6283017.html

 

一、requests模块

 

requests.post(
    url = "xxx",
    header = {xxx:xxx},
    cookies = {},
    params = {}    #这是加在url后面的参数
    data = {}, 
    json = {}
    #data和json都是发送请求体中的数据，但是json会把数据自动加工成json格式的数据

######代理######
    proxies = {            #根据http和https向代理网站放松请求
        "http": "xxxxx",      #或者指定某个网站跳转到另一个网站 "https:xxxxx": "xxxxx"
        "https": "xxxxx"   
    },
    auth = HTTPProxyAuth("用户名", "密码"),

######文件上传######
    files = {"f1": open("xxx", "rb")}

######超时时间######
    timeout = 1    #如果只有一个表示连接的等待时间
    timeout = （5,1）  #表示连接的时间和等待返回结果的时间

######允许重定向######
    allow_redirects = False

######大文件下载######
    stream = True      #一点一点下载
)

 

二、BeautifulSoup模块

 1 from bs4 import BeautifulSoup
 2  
 3 html_doc = """
 4 <html><head><title>The Dormouse's story</title></head>
 5 <body>
 6 asdf
 7     <div class="title">
 8         <b>The Dormouse's story总共</b>
 9         <h1>f</h1>
10     </div>
11 <div class="story">Once upon a time there were three little sisters; and their names were
12     <a  class="sister0" id="link1">Els<span>f</span>ie</a>,
13     <a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
14     <a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
15 and they lived at the bottom of a well.</div>
16 ad<br/>sf
17 <p class="story">...</p>
18 </body>
19 </html>
20 """
21  
22 soup = BeautifulSoup(html_doc, features="lxml")
23 # 找到第一个a标签
24 tag1 = soup.find(name='a')
25 # 找到所有的a标签
26 tag2 = soup.find_all(name='a')
27 # 找到id＝link2的标签
28 tag3 = soup.select('#link2')

 

三、长轮询

实现机制：利用队列，如果队列为空则夯住，超出时间则再次请求

创建一个存放队列的字典，每一个请求到来时，在字典中创建这个用户的键值对，值就是属于他的队列，如果有人投票，则循环整个字典，给每个队列都添加新的数据。每个五秒发一次请求，如果没人投票则一直等待，直到五秒后在此发送请求。

import queue
import threading
from flask import Blueprint, render_template, request, jsonify, session

t = Blueprint("t", __name__)

uuid = threading.get_ident()

vote_count = {
    1: {"name": "李静", "count": 1},
    2: {"name": "胡岳枫", "count": 2}
}

queue_dic = {}   #队列列表

@t.route("/user_info", methods=["GET", "POST"])
def user_info():
    queue_dic[uuid] = queue.Queue()

    return render_template("user_info.html", vote_count=vote_count)

@t.route("/vote", methods=["GET","POST"])
def vote():
    user_id = int(request.form.get("user_id"))
    vote_count[user_id]["count"] += 1
    for v in queue_dic.values():
        v.put(vote_count)
    return "success"

@t.route("/get_vote")
def get_vote():
    ret = {"status": True, "data": None}
    try:
        val = queue_dic[uuid].get(timeout=5)
        ret["data"] = val
    except:
        ret["status"] = False

    return jsonify(ret)
后端代码

 

 

一、requests模块

1.基本使用

import requests
url = 'xxxx'
params = {'xxx': 'xxx'}
headers = {'User-Agent': 'xxx'}
response = requests.get(url=url, params=params, headers=headers)
response.text  # 纯文本html

 

posted @ 2019-05-12 21:07  不可思议的猪  阅读(219)  评论(0)  编辑  收藏  举报