数据库连接池

python dbutils

DBUtils是一套Python数据库连接池包，并允许对非线程安全的数据库接口进行线程安全包装。

DBUtils提供两种外部接口：

• PersistentDB ：提供线程专用的数据库连接，并自动管理连接。

• PooledDB ：提供线程间可共享的数据库连接，并自动管理连接。

  安装

  DBUtils pip install DBUtils
  pymysql pip install pymysql/MySQLdb

db_config.py 配置文件

# -*- coding: UTF-8 -*-
import pymysql

# 数据库信息
DB_TEST_HOST = "127.0.0.1"
DB_TEST_PORT = 3306
DB_TEST_DBNAME = "ball"
DB_TEST_USER = "root"
DB_TEST_PASSWORD = "123456"

# 数据库连接编码
DB_CHARSET = "utf8"

# mincached : 启动时开启的闲置连接数量(缺省值 0 开始时不创建连接)
DB_MIN_CACHED = 10

# maxcached : 连接池中允许的闲置的最多连接数量(缺省值 0 代表不闲置连接池大小)
DB_MAX_CACHED = 10

# maxshared : 共享连接数允许的最大数量(缺省值 0 代表所有连接都是专用的)如果达到了最大数量,被请求为共享的连接将会被共享使用
DB_MAX_SHARED = 20

# maxconnecyions : 创建连接池的最大数量(缺省值 0 代表不限制)
DB_MAX_CONNECYIONS = 100

# blocking : 设置在连接池达到最大数量时的行为(缺省值 0 或 False 代表返回一个错误<toMany......> 其他代表阻塞直到连接数减少,连接被分配)
DB_BLOCKING = True

# maxusage : 单个连接的最大允许复用次数(缺省值 0 或 False 代表不限制的复用).当达到最大数时,连接会自动重新连接(关闭和重新打开)
DB_MAX_USAGE = 0

# setsession : 一个可选的SQL命令列表用于准备每个会话，如["set datestyle to german", ...]
DB_SET_SESSION = None

# creator : 使用连接数据库的模块
DB_CREATOR = pymysql

db_dbutils_init.py 创建数据池初始化

from DBUtils.PooledDB import PooledDB
import db_config as config

"""
@功能：创建数据库连接池
"""

class MyConnectionPool(object):
    __pool = None

    # def __init__(self):
    #     self.conn = self.__getConn()
    #     self.cursor = self.conn.cursor()

    # 创建数据库连接conn和游标cursor
    def __enter__(self):
        self.conn = self.__getconn()
        self.cursor = self.conn.cursor()

    # 创建数据库连接池
    def __getconn(self):
        if self.__pool is None:
            self.__pool = PooledDB(
                creator=config.DB_CREATOR,
                mincached=config.DB_MIN_CACHED,
                maxcached=config.DB_MAX_CACHED,
                maxshared=config.DB_MAX_SHARED,
                maxconnections=config.DB_MAX_CONNECYIONS,
                blocking=config.DB_BLOCKING,
                maxusage=config.DB_MAX_USAGE,
                setsession=config.DB_SET_SESSION,
                host=config.DB_TEST_HOST,
                port=config.DB_TEST_PORT,
                user=config.DB_TEST_USER,
                passwd=config.DB_TEST_PASSWORD,
                db=config.DB_TEST_DBNAME,
                use_unicode=False,
                charset=config.DB_CHARSET
            )
        return self.__pool.connection()

    # 释放连接池资源
    def __exit__(self, exc_type, exc_val, exc_tb):
        self.cursor.close()
        self.conn.close()

    # 关闭连接归还给链接池
    # def close(self):
    #     self.cursor.close()
    #     self.conn.close()

    # 从连接池中取出一个连接
    def getconn(self):
        conn = self.__getconn()
        cursor = conn.cursor()
        return cursor, conn


# 获取连接池,实例化
def get_my_connection():
    return MyConnectionPool()

制作mysqlhelper.py

from db_dbutils_init import get_my_connection

"""执行语句查询有结果返回结果没有返回0；增/删/改返回变更数据条数，没有返回0"""


class MySqLHelper(object):
    def __init__(self):
        self.db = get_my_connection()  # 从数据池中获取连接

    def __new__(cls, *args, **kwargs):
        if not hasattr(cls, 'inst'):  # 单例
            cls.inst = super(MySqLHelper, cls).__new__(cls, *args, **kwargs)
        return cls.inst

    # 封装执行命令
    def execute(self, sql, param=None, autoclose=False):
        """
        【主要判断是否有参数和是否执行完就释放连接】
        :param sql: 字符串类型，sql语句
        :param param: sql语句中要替换的参数"select %s from tab where id=%s" 其中的%s就是参数
        :param autoclose: 是否关闭连接
        :return: 返回连接conn和游标cursor
        """
        cursor, conn = self.db.getconn()  # 从连接池获取连接
        count = 0
        try:
            # count : 为改变的数据条数
            if param:
                count = cursor.execute(sql, param)
            else:
                count = cursor.execute(sql)
            conn.commit()
            if autoclose:
                self.close(cursor, conn)
        except Exception as e:
            pass
        return cursor, conn, count

    # 执行多条命令
    # def executemany(self, lis):
    #     """
    #     :param lis: 是一个列表，里面放的是每个sql的字典'[{"sql":"xxx","param":"xx"}....]'
    #     :return:
    #     """
    #     cursor, conn = self.db.getconn()
    #     try:
    #         for order in lis:
    #             sql = order['sql']
    #             param = order['param']
    #             if param:
    #                 cursor.execute(sql, param)
    #             else:
    #                 cursor.execute(sql)
    #         conn.commit()
    #         self.close(cursor, conn)
    #         return True
    #     except Exception as e:
    #         print(e)
    #         conn.rollback()
    #         self.close(cursor, conn)
    #         return False

    # 释放连接
    def close(self, cursor, conn):
        """释放连接归还给连接池"""
        cursor.close()
        conn.close()

    # 查询所有
    def selectall(self, sql, param=None):
        try:
            cursor, conn, count = self.execute(sql, param)
            res = cursor.fetchall()
            return res
        except Exception as e:
            print(e)
            self.close(cursor, conn)
            return count

    # 查询单条
    def selectone(self, sql, param=None):
        try:
            cursor, conn, count = self.execute(sql, param)
            res = cursor.fetchone()
            self.close(cursor, conn)
            return res
        except Exception as e:
            print("error_msg:", e.args)
            self.close(cursor, conn)
            return count

    # 增加
    def insertone(self, sql, param):
        try:
            cursor, conn, count = self.execute(sql, param)
            # _id = cursor.lastrowid()  # 获取当前插入数据的主键id，该id应该为自动生成为好
            conn.commit()
            self.close(cursor, conn)
            return count
            # 防止表中没有id返回0
            # if _id == 0:
            #     return True
            # return _id
        except Exception as e:
            print(e)
            conn.rollback()
            self.close(cursor, conn)
            return count

    # 增加多行
    def insertmany(self, sql, param):
        """
        :param sql:
        :param param: 必须是元组或列表[(),()]或（（），（））
        :return:
        """
        cursor, conn, count = self.db.getconn()
        try:
            cursor.executemany(sql, param)
            conn.commit()
            return count
        except Exception as e:
            print(e)
            conn.rollback()
            self.close(cursor, conn)
            return count

    # 删除
    def delete(self, sql, param=None):
        try:
            cursor, conn, count = self.execute(sql, param)
            self.close(cursor, conn)
            return count
        except Exception as e:
            print(e)
            conn.rollback()
            self.close(cursor, conn)
            return count

    # 更新
    def update(self, sql, param=None):
        try:
            cursor, conn, count = self.execute(sql, param)
            conn.commit()
            self.close(cursor, conn)
            return count
        except Exception as e:
            print(e)
            conn.rollback()
            self.close(cursor, conn)
            return count


if __name__ == '__main__':
    db = MySqLHelper()
    # # 查询单条
    # sql1 = 'select * from userinfo where name=%s'
    # args = 'python'
    # ret = db.selectone(sql=sql1, param=args)
    # print(ret)  # (None, b'python', b'123456', b'0')
    # 增加单条
    # sql2 = 'insert into userinfo (name,password) VALUES (%s,%s)'
    # ret = db.insertone(sql2, ('old2','22222'))
    # print(ret)
    # 增加多条
    # sql3 = 'insert into userinfo (name,password) VALUES (%s,%s)'
    # li = li = [
    #     ('分省', '123'),
    #     ('到达','456')
    # ]
    # ret = db.insertmany(sql3,li)
    # print(ret)
    # 删除
    # sql4 = 'delete from  userinfo WHERE name=%s'
    # args = 'xxxx'
    # ret = db.delete(sql4, args)
    # print(ret)
    # 更新
    # sql5 = r'update userinfo set password=%s WHERE name LIKE %s'
    # args = ('993333993', '%old%')
    # ret = db.update(sql5, args)
    # print(ret)