IO编程----序列化

pickle

import pickle

d={'name':'Bob','age':20,'score':88}

'''
pickle.dump直接将对象序列化并写入一个file-like Object
'''
with open('dump.txt','wb') as f:
    pickle.dump(d,f)


'''
pickle.load()方法从一个file-like Object中直接反序列化出对象
'''
with open('dump.txt','rb') as f:
    d=pickle.load(f)
    print(d)

Json

import json

d={'name':'Bob','age':20,'score':88}

with open('testJson','w') as f:
    json.dump(d,f)

with open('testJson','r') as f:
    print(json.load(f))

Json高级进阶

import json

d={'name':'Bob','age':20,'score':88}

with open('testJson','w') as f:
    json.dump(d,f)

with open('testJson','r') as f:
    print(json.load(f))



obj = dict(name='小明', age=20)
#ensure_ascii=True,值为True，则序列化保存为ascii码，为False，保存为原始编码
s = json.dumps(obj, ensure_ascii=True)
print(s)

#一般情况下，我们会序列化类对象
class student(object):
    def __init__(self,name,age,score):
        self.name=name
        self.age=age
        self.score=score

s=student('wangxy',20,88)

'''
json.dumps(s)直接序列化对象会输出，
raise TypeError(repr(o) + " is not JSON serializable")
TypeError: <__main__.student object at 0x7fa705cf05f8> is not JSON serializable
'''

#dump和dumps方法中的可选参数default就是把任意一个对象变成一个可序列为JSON的对象
def studentToDict(stu):
    return {
        'name':stu.name,
        'age':stu.age,
        'score':stu.score
    }

with open('classToJson','w') as f:
    json.dump(s,f,default=studentToDict)

#将json反序列化为类对象实例
def dictToStudent(d):
    return student(d['name'],d['age'],d['score'])

with open('classToJson','r') as f:
    print(json.load(f,object_hook=dictToStudent))

#通常情况下，class类都有一个__dict__，它就是dict，用来存储实例变量，
print(json.dumps(s,default=lambda obj:obj.__dict__))


输出：

{'name': 'Bob', 'score': 88, 'age': 20}
{"name": "u5c0fu660e", "age": 20}
<__main__.student object at 0x7f7ac4a906d8>
{"name": "wangxy", "age": 20, "score": 88}