Flask DBUtils

作用：创建连接池，解决多线程问题

1、安装模块

pip3 install -i https://pypi.douban.com/simple DBUtils

2、settings.py(配置文件)

from DBUtils.PooledDB import PooledDB
import pymysql

#

class Config:
    POOL = PooledDB(
        creator=pymysql,  # 使用链接数据库的模块
        maxconnections=6,  # 连接池允许的最大连接数，0和None表示不限制连接数
        mincached=2,  # 初始化时，链接池中至少创建的空闲的链接，0表示不创建
        maxcached=5,  # 链接池中最多闲置的链接，0和None不限制
        maxshared=3,
        # 链接池中最多共享的链接数量，0和None表示全部共享。PS: 无用，因为pymysql和MySQLdb等模块的 threadsafety都为1
        # ，所有值无论设置为多少，_maxcached永远为0，所以永远是所有链接都共享。
        blocking=True,  # 连接池中如果没有可用连接后，是否阻塞等待。True，等待；False，不等待然后报错
        maxusage=None,  # 一个链接最多被重复使用的次数，None表示无限制
        setsession=[],  # 开始会话前执行的命令列表。如：["set datestyle to ...", "set time zone ..."]
        ping=0,
        # ping MySQL服务端，检查是否服务可用。# 如：0 = None = never, 1 = default = whenever it is requested,
        # 2 = when a cursor is created, 4 = when a query is executed, 7 = always
        host='127.0.0.1',
        port=3306,
        user='root',
        password='密码',
        database='DBU',
        charset='utf8'
    )

3、在其它模块中使用 xx.py

import pymysql
from settings import Config

con = Config.POOL.connection()
cursor = con.cursor(cursor=pymysql.cursors.DictCursor)
sql = "select name, line from userinfo where name=%s"
args = 'tom'
cursor.execute(sql, (args,))
data = cursor.fetchall()
print(data)
cursor.close()
con.close()

优化：封装函数

import pymysql
from settings import Config

def connect_database(sql, args):
    con = Config.POOL.connection()
    cursor = con.cursor(cursor=pymysql.cursors.DictCursor)
    cursor.execute(sql, (args,))
    data = cursor.fetchall()
    # print(data)
    cursor.close()
    con.close()
    return data

sql = "select name, line from userinfo where name=%s"
args = 'tom'

ret = connect_database(sql, args)
print(ret)

终极优化

import pymysql
from settings import Config

def db_connect():
    con = Config.POOL.connection()
    cursor = con.cursor(cursor=pymysql.cursors.DictCursor)
    return con, cursor

def db_connect_close(cursor, con):
    cursor.close()
    con.close()

def fetch_all(sql, args):
    con, cursor = db_connect()
    # con = Config.POOL.connection()
    # cursor = con.cursor(cursor=pymysql.cursors.DictCursor)
    cursor.execute(sql, (args,))
    data = cursor.fetchall()
    # print(data)
    db_connect_close(cursor, con)
    # cursor.close()
    # con.close()
    return data

# sql = "select name, line from userinfo where name=%s"
# args = 'tom'
#
#
# ret = fetch_all(sql, args)
# print(ret)

调用

from xx import fetch_all

sql = "select name, line from userinfo where name=%s"
args = 'tom'

ret = fetch_all(sql, args)
print(ret)