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
以上这篇python 爬虫 实现增量去重和定时爬取实例就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持脚本之家。
