python 爬虫实现增量去重和定时爬取实例

发布时间：2020-09-22 16:06:04 作者：X_Special
来源：脚本之家阅读：123

前言：在爬虫过程中，我们可能需要重复的爬取同一个网站，为了避免重复的数据存入我们的数据库中通过实现增量去重去解决这一问题本文还针对了那些需要实时更新的网站增加了一个定时爬取的功能；

本文作者同开源中国（殊途同归_）；

解决思路：

1.获取目标url

2.解析网页

3.存入数据库（增量去重）

4.异常处理

5.实时更新（定时爬取）

下面为数据库的配置 mysql_congif.py：

import pymysql
 
 
def insert_db(db_table, issue, time_str, num_code):
  host = '127.0.0.1'
  user = 'root'
  password = 'root'
  port = 3306
  db = 'lottery'
  data_base = pymysql.connect(host=host, user=user, password=password, port=port, db=db)
  cursor = data_base.cursor()
  try:
    sql = "INSERT INTO %s VALUES ('%s','%s','%s')" % (db_table, issue, time_str, num_code)
    cursor.execute(sql)
    data_base.commit()
  except ValueError as e:
    print(e)
    data_base.rollback()
  finally:
    cursor.close()
    data_base.close()
 
 
def select_db(issue, db_table):
  host = '127.0.0.1'
  user = 'root'
  password = 'root'
  port = 3306
  db = 'lottery'
  data_base = pymysql.connect(host=host, user=user, password=password, port=port, db=db)
  cursor = data_base.cursor()
  try:
    sql = "SELECT '%s' FROM %s " % (issue, db_table)
    cursor.execute(sql)
    data_base.commit()
  except ValueError as e:
    print(e)
    data_base.rollback()
  finally:
    return issue

接下来是主要代码 test.py：

# 使用bs4进行网页解析
# 实现了增量去重
# 实现了定时爬取
import datetime
import time
 
from bs4 import BeautifulSoup
import requests
 
 
from mysql_config import insert_db
from mysql_config import select_db
 
 
def my_test():
  db_table = 'lottery_table'
  url = 'http://kj.13322.com/kl10_dkl10_history_dtoday.html'
  res = requests.get(url)
  content = res.content
  soup = BeautifulSoup(content, 'html.parser', from_encoding='utf8')
  c_t = soup.select('#trend_table')[0]
  trs = c_t.contents[4:]
  for tr in trs:
    if tr == '\n':
      continue
    tds = tr.select('td')
    issue = tds[1].text
    time_str = tds[0].text
    num_code = tr.table.text.replace('\n0', ',').replace('\n', ',').strip(',')
    print('期号：%s\t时间：%s\t号码:%s' % (str(issue), str(time_str), str(num_code)))
    issue_db = select_db(issue, db_table)
    try:
      if issue_db == issue:
        insert_db(db_table, issue_db, time_str, num_code)
        print('添加%s到%s成功' % (issue_db, db_table))
    except Exception as e:
      print('%s 已经存在！' % issue_db)
      print(e)
 
 
if __name__ == '__main__':
  flag = 0
  now = datetime.datetime.now()
  sched_time = datetime.datetime(now.year, now.month, now.day, now.hour, now.minute, now.second) +\
         datetime.timedelta(seconds=3)
  while True:
    now = datetime.datetime.now()
    if sched_time < now:
      time.sleep(3)
      print(now)
      my_test()
      flag = 1
    else:
      if flag == 1:
        sched_time = sched_time + datetime.timedelta(minutes=2)
        flag = 0

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python 爬虫 实现增量去重和定时爬取实例

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