python对象持久化

pickle模块

import pickle
person = {'name':'MT','age':25}
s = pickle.dumps(person)
p = pickle.loads(s)
pickle.dump(person,open('pickle_db','wb'))
p = pickle.load(open('pickle_db','rb'))
print(p)
print(type(p))

shelve模块

import shelve
scores = [99,100,88]
student = {'name':'MT','age':25}
db  = shelve.open('shelve_student')#声明创建一个数据库
db['s'] = student #将字典表student序列化到数据库文件里，并且赋予键值's'
db['scores'] = scores
len(db) #检查数据库中有几个对象，用len()查看键值
2
temp_student = db['s']
temp
Traceback (most recent call last):
  File "<input>", line 1, in <module>
NameError: name 'temp' is not defined
temp_student
{'name': 'MT', 'age': 25}
type(temp_student)
<class 'dict'>
temp_scores
[99, 100, 88]
type(temp_scores)
<class 'list'>

shelve序列化自定义类实例

import  shelve
class Student:
    def __init__(self,name,age):
        self.name = name
        self.age = age

    def __str__(self):
        return self.name

def wirte_shelve():
    s = Student('Tom',25)
    db = shelve.open('shelve_student_db')
    db['s'] = s
    db.close()

def read_shelve():
    db = shelve.open('shelve_student_db')
    st = db['s']
    print(st)
    print(st.name)
    print(st.age)
    db.close()


if __name__ == '__main__':
    read_shelve()