10.11 作业

1、定义MySQL类

（参考答案：http://www.cnblogs.com/linhaifeng/articles/7341177.html#_label5）
1.对象有id、host、port三个属性
2.定义工具create_id，在实例化时为每个对象随机生成id，保证id唯一

3.提供两种实例化方式，方式一：用户传入host和port 方式二：从配置文件中读取host和port进行实例化

4.为对象定制方法，save和get_obj_by_id，save能自动将对象序列化到文件中，文件路径为配置文件中DB_PATH,文件名为id号，保存之前验证对象是否已经存在，若存在则抛出异常，;get_obj_by_id方法用来从文件中反序列化出对象

#setting.py 内容
'''
HOST='127.0.0.1'
PORT='333653024'
DB_PATH=r'K:\Python课程\上课视频\db\cof'
'''
import settings
import uuid
import pickle
import os
class MYSQL:
    def __init__(self,host,port):
        self.id=self.create_id()
        self.host=host
        self.port=port
    def save(self):
        if not self.is_exists:
            raise PermissionError('对象已存在')
        file_path=r'%s%s%s' %(settings.DB_PATH,os.sep,self.id)
        pickle.dump(self,open(file_path,'wb'))

    @property
    def is_exists(self):
        tag=True
        files=os.listdir(settings.DB_PATH)
        for file in files:
            file_abspath=r'%s%s%s' %(settings.DB_PATH,os.sep,file)
            obj=pickle.load(open(file_abspath,'rb'))
            if self.host==obj.host and self.port==obj.port:
                tag=False
                break

        return tag
    
    def get_obj_by_id(self):
        file_abspath=r'%s%s%s'%(settings.DB_PATH,os.sep,self.id)
        return pickle.load(open(file_abspath,'rb'))
    @staticmethod
    def create_id():
        return str(uuid.uuid1())
    @classmethod
    def from_conf(cls):
        print(cls)
        return cls(settings.HOST,settings,PORT)

print(MYSQL.from_conf)  #<bound method MySQL.from_conf of <class '__main__.MySQL'>>
conn=MYSQL.from_conf()
conn.save()
conn.get_obj_by_id() #<class '__main__.MYSQL'>

conn1=MYSQL('127.0.0.1',3306)
conn1.save() #抛出异常PermissionError: 对象已存在

2、定义一个类：圆形，该类有半径，周长，面积等属性，将半径隐藏起来，将周长与面积开放

import math

class Circle:
    def __init__(self,radius):
        self.__radius=radius

    @property
    def area(self):
        return math.pi * self.__radius**2

    @property
    def perimeter(self):
        return 2*math.pi*self.__radius

c=Circle(10)
print(c.area)  #314.1592653589793
print(c.perimeter)  #62.83185307179586

3、使用abc模块定义一个phone抽象类并编写一个具体的实现类

import abc


class Animal(metaclass=abc.ABCMeta):

    # 吃
    @abc.abstractmethod
    def eat(self):
        pass

    # 喝
    @abc.abstractmethod
    def drink(self):
        pass

    # 叫
    @abc.abstractmethod
    def speak(self):
        pass


# 猪
class Pig(Animal):
    # 吃
    def eat(self):
        print('猪在吃饭')
        pass

    # 喝
    def drink(self):
        pass


    def speak(self):
        print('哼哼哼~~~')


    # 派生
    def run(self):
        pass
pig = Pig()

1、定义MySQL类

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