python 爬蟲實現(xiàn)增量去重和定時爬取實例

更新時間：2020年02月28日 07:41:49 作者：X_Special

今天小編就為大家分享一篇python 爬蟲實現(xiàn)增量去重和定時爬取實例，具有很好的參考價值，希望對大家有所幫助。一起跟隨小編過來看看吧

前言：在爬蟲過程中，我們可能需要重復的爬取同一個網(wǎng)站，為了避免重復的數(shù)據(jù)存入我們的數(shù)據(jù)庫中通過實現(xiàn)增量去重去解決這一問題本文還針對了那些需要實時更新的網(wǎng)站增加了一個定時爬取的功能；

本文作者同開源中國（殊途同歸_）；

解決思路：

1.獲取目標url

2.解析網(wǎng)頁

3.存入數(shù)據(jù)庫（增量去重）

4.異常處理

5.實時更新（定時爬取）

下面為數(shù)據(jù)庫的配置 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

接下來是主要代碼 test.py：

# 使用bs4進行網(wǎng)頁解析
# 實現(xiàn)了增量去重
# 實現(xiàn)了定時爬取
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('期號：%s\t時間：%s\t號碼:%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 已經(jīng)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

以上這篇python 爬蟲實現(xiàn)增量去重和定時爬取實例就是小編分享給大家的全部內(nèi)容了，希望能給大家一個參考，也希望大家多多支持腳本之家。

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