python基础：类与对象，数据持久化

绝地灬酷狼 2022-04-23 09:20 135阅读 0赞

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2V5ZW9mZWFnbGU_size_16_color_FFFFFF_t_70]

# 1，创建父类，子类继承 #

people.py: 父类

class people:
        def __init__(self,name, age,job=None):
            self.name=name
            self.age=age
            self.job=job
    
        def getName(self):
            return self.name
        def setAge(self,age):
            self.age=age
    
    
    #创建对象
    if __name__== "__main__":
        p1=people("lisi",23,"spark-enginer")
        p2=people("zs",43)
    
        p1.setAge(34)
        print(p1.getName())#lisi
        print(p1.age)#34
    
        peopleArr=[p1,p2]
        #遍历方式1
        # for per in peopleArr:
        #     print(per.name,per.age, per.job)
    
        #遍历方式2
        # tup3=[(per.name,per.age,per.job) for per in peopleArr]
        # for info in tup3:
        #     print(info[0], info[1], info[2])
    
        #遍历方式3:
        # tup3=[(per.name,per.age, per.job) for per in peopleArr if per.age>30 ]
        # for info in tup3:
        #     print(info[0], info[1], info[2])
    
        #遍历方式4
        ageArr=[(per.age+10 if per.age<30 else per.age) for per in peopleArr]
        for age in ageArr:
            print(age)#33, 43

子类 teacher.py： 继承父类

#继承people类
    from chapter1.oop.people import people
    class teacher(people):
        #构造方法：重写父类构造
        def __init__(self,name ,age):
            people.__init__(self,name,age, job="teacher")
        # def __init__(self,name): 构造方法，重载无效，只认参数少的
        #     people.__init__(self,name,30, job="teacher")
    
        # 普通方法：重写父类普通方法
        def getName(self):
            return "teacher_"+self.name+", "+people.getName(self)
    
        #重写toString方法：打印一个对象
        def __str__(self):
            return self.name+","+str(self.age)+","+self.job
    
    #创建对象
    t2=teacher("t2",43)
    if __name__=="__main__":
        #重写父类构造后， 必须使用以重写的构造方法，否则报错
        # t1= teacher("t1",34,"Teacher")
        # print(t1.getName())#teacher_t1
        # print(t1)
    
        print(t2.getName())
        print(t2,1)
    
    #teacher_t2, t2
    #t2,43,teacher

# 2，对象的持久化 #

save\_obj.py

#导入对象，保存到文件中
    from chapter1.oop.class_obj.teacher import t2
    import shelve
    
    filename="data/shelve_obj"
    def save_data():
        #创建字典
        dict=shelve.open(filename)
        dict["obj"]=t2
        #关闭字典
        dict.close()
    
    def read_data():
        #创建字典
        dict=shelve.open(filename)
        for key in dict:
            # print(key, ",", dict[key])#调用被重写的__str__方法： obj , t2,43,teacher
            print(dict[key].name)#t2
            print(dict[key].age)#43
            print(dict[key].job)#teacher
            print(dict[key].getName())#调用对象的方法
    
    save_data()
    read_data()

数据查询： interactive\_select.py

#使用输入输出，循环： 进行交互
    #通过shelve打开已保存的字典数据， input接收输入的key , 异常处理-获取数据-展示
    import shelve
    fileName="data/shelve_obj"
    fieldNames=("name","age","job")
    
    #数据
    max_field_len=max(len(f) for f in fieldNames) #4
    db=shelve.open(fileName)
    
    while True:
        key=input("请输入一个字典的key: [空格退出]")
    
        #判断输入，进行处理
        if not key :#空格，退出
            break
        try:
            #打开字典
            dict=shelve.open(fileName)
            record=dict[key]
        except:#出现异常
            print("error...字典中不存在这个key(%s)" %key)
        else:#没有异常
            for field in fieldNames: #左对齐输出：属性-属性值
                print(field.ljust(max_field_len), "===> ",getattr(record,field))
    
    #请输入一个字典的key: obj
    #name ===>  t2
    #age  ===>  43
    #job  ===>  teacher

数据更新，插入  
interactive\_test\_update.py

#用输入的数据，更新文件中的数据
    import shelve
    from chapter1.oop.class_obj.teacher import teacher
    
    fildNames=("name","age","job")
    fileName="data/shelve_obj"
    
    #读取数据
    db=shelve.open(fileName)
    while True:
        #输入数据
        key=input("输入字典的key ")
        # 取出字典中的值， 更新
        if not key : break
    
        if  key in db:
            record=db[key]
        else:
            record=teacher(name='?',age='?')
    
        #遍历所有所有属性, 取出属性值
        for field in fildNames:
            field_val=getattr(record, field)
            fild_val_new=input("输入[%s] 的值: "%field)
    
            if fild_val_new :#赋值
                setattr(record, field,fild_val_new)
    
        #保存数据
        db[key]=record
        db.close()
        print("数据保存ok...")

测试：插入数据  
![在这里插入图片描述][2019020518404689.png]  
查询验证：刚插入的数据  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2V5ZW9mZWFnbGU_size_16_color_FFFFFF_t_70 1]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2V5ZW9mZWFnbGU_size_16_color_FFFFFF_t_70]: /images/20220321/fedb78e8ffd04fec8cc1b5256d9e1e9d.png
[2019020518404689.png]: /images/20220321/5bdcef136ea44e4abe89b9d29e9f7cea.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2V5ZW9mZWFnbGU_size_16_color_FFFFFF_t_70 1]: /images/20220321/d542a0580a6b4042b77eacf3bebaf69c.png