import pymysql
import configparser
from dbutils.pooled_db import PooledDB


class UseDatabase:
    # 连接池对象
    __pool = None

    def __init__(self):
        config = configparser.ConfigParser()
        config.read("database.conf", encoding="utf-8")
        self.pool = UseDatabase.__get_conn(config)

    @staticmethod
    def __get_conn(config):
        """
        @summary: 静态方法，从连接池中取出连接
        @return MySQLdb.connection
        """
        db_host = config.get("db", "db_host")
        db_user = config.get("db", "db_user")
        db_pass = config.get("db", "db_pass")
        db_name = config.get("db", "db_name")
        if UseDatabase.__pool is None:
            __pool = PooledDB(pymysql, mincached=1, maxcached=10, maxconnections=10,
                              host=db_host, port=3306, user=db_user, passwd=db_pass,
                              db=db_name, use_unicode=True, blocking=False, charset="utf8")
        return __pool

    def get_all(self, sql):
        try:
            con = self.pool.connection()
            # cur = con.cursor(cursor=pymysql.cursors.DictCursor)
            cur = con.cursor()
            count = cur.execute(sql)
            if count > 0:
                result = cur.fetchall()
            else:
                result = False
            return result
        except Exception as err:
            raise type(err)(err)
        finally:
            cur.close()
            con.close()

    def get_all_dict(self, sql):
        try:
            con = self.pool.connection()
            cur = con.cursor(cursor=pymysql.cursors.DictCursor)
            count = cur.execute(sql)
            if count > 0:
                result = cur.fetchall()
            else:
                result = False
            return result
        except Exception as err:
            raise type(err)(err)
        finally:
            cur.close()
            con.close()

    def update(self, sql, val):
        try:
            con = self.pool.connection()
            cur = con.cursor()
            cur.execute(sql, val)
            con.commit()
        except Exception as err:
            con.rollback()  # 事务回滚
            raise type(err)(err)
        finally:
            cur.close()
            con.close()


if __name__ == '__main__':
    conn = UseDatabase()
    sql = "show databases;"
    results = conn.get_all(sql)
    print(results)