序列化模块的pickle模块,shelve模块

pick模块


dump的结果是bytes,dump用的f文件句柄需要以wb的形式打开,load所用的f是'rb'模式
支持几乎所有对象的序列化
对于对象的序列化需要这个对象对应的类在内存中
对于多次dump/load的操作做了良好的处理

dic = {1:(12,3,4),('a','b'):4}
import  pickle

pic_dic = pickle.dumps(dic)
print(pic_dic)    # bytes类型
new_dic = pickle.loads(pic_dic)
print(new_dic)

# pickle支持几乎所有对象的
class Student:
    def __init__(self,name,age):
        self.name = name
        self.age = age

alex = Student('alex',83)
ret = pickle.dumps(alex)
小花 = pickle.loads(ret)
print(小花.name)
print(小花.age)

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

alex = Student('alex',83)
with open('pickle_demo','wb') as f:
    pickle.dump(alex,f)
with open('pickle_demo','rb') as f:
    旺财 = pickle.load(f)
    print(旺财.name)

# 学员选课系统  pickle模块来存储每个学员的对象

# with open('pickle_demo','wb') as f:
#     pickle.dump({'k1':'v1'}, f)
#     pickle.dump({'k11':'v1'}, f)
#     pickle.dump({'k11':'v1'}, f)
#     pickle.dump({'k12':[1,2,3]}, f)
#     pickle.dump(['k1','v1','l1'], f)

# with open('pickle_demo','rb') as f:
#     while True:
#         try:
#             print(pickle.load(f))
#         except EOFError:
#             break

　　

shelve模块

import shelve
f = shelve.open('shelve_demo')
f['key'] = {'k1':(1,2,3),'k2':'v2'}
f.close()

f = shelve.open('shelve_demo')
content = f['key']
f.close()
print(content)

# shelve  如果你写定了一个文件
# 改动的比较少
# 读文件的操作比较多
# 且你大部分的读取都需要基于某个key获得某个value