import pymysql

from DBUtils.PooledDB import PooledDB, SharedDBConnection

'''

连接池

'''

class MysqlPool(object):

    def __init__(self):

        self.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='root',

            database='test',

            charset='utf8'

        )

    def __new__(cls, *args, **kw):

        '''

        启用单例模式

        :param args:

        :param kw:

        :return:

        '''

        if not hasattr(cls, '_instance'):

            cls._instance = object.__new__(cls)

        return cls._instance

    def connect(self):

        '''

        启动连接

        :return:

        '''

        conn = self.POOL.connection()

        cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)

        return conn, cursor

    def connect_close(self,conn, cursor):

        '''

        关闭连接

        :param conn:

        :param cursor:

        :return:

        '''

        cursor.close()

        conn.close()

    def fetch_all(self,sql, args):

        '''

        批量查询

        :param sql:

        :param args:

        :return:

        '''

        conn, cursor = self.connect()

        cursor.execute(sql, args)

        record_list = cursor.fetchall()

        self.connect_close(conn, cursor)

        return record_list

    def fetch_one(self,sql, args):

        '''

        查询单条数据

        :param sql:

        :param args:

        :return:

        '''

        conn, cursor = self.connect()

        cursor.execute(sql, args)

        result = cursor.fetchone()

        self.connect_close(conn, cursor)

        return result

    def insert(self,sql, args):

        '''

        插入数据

        :param sql:

        :param args:

        :return:

        '''

        conn, cursor = self.connect()

        row = cursor.execute(sql, args)

        conn.commit()

        self.connect_close(conn, cursor)

        return row

#实例化

mp=MysqlPool()

'''

查询单条

'''

username='admin'

data = mp.fetch_one("select id,nickname from userinfo where user=%s",(username,))

print(data)

'''

批量读取

'''

data = mp.fetch_all("select * from record where user_id=%s",(1,))

print(data)

'''

插入数据

'''

data = mp.insert("insert into record(line,ctime,user_id)values(%s,%s,%s)",(22,'2019-11-11',1))

print(data)