老生常谈Python序列化和反序列化

dic = {'age': 23, 'job': 'student'}
byte_data = pickle.dumps(dic)
# out -> b'\x80\x03}q\x00(X\x03\x00\x00\...'
print(byte_data)

obj = pickle.loads(byte_data)
print(obj)

# 序列化
with open('abc.pkl', 'wb') as f:
  dic = {'age': 23, 'job': 'student'}
  pickle.dump(dic, f)
# 反序列化
with open('abc.pkl', 'rb') as f:
  aa = pickle.load(f)
  print(aa)
  print(type(aa)) # <class 'dict'>

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

  def work(self):
    print(self.name, 'is working...')

# 将实例存储在变量中，当然也能存在文件中
a_person = Person('abc', 22, 'waiter')
person_abc = pickle.dumps(a_person)
p = pickle.loads(person_abc)
p.work()
# 将类本身存储在变量中，loads的时候返回类本身，而非它的一个实例
class_Person = pickle.dumps(Person)
Person = pickle.loads(class_Person)
p = Person('Bob', 23, 'Student')
p.work()

# 下面这个例子演示的就是将类存储在文件中
# 序列化
with open('person.pkl', 'wb') as f:
  pickle.dump(Person, f)
# 反序列化
with open('person.pkl', 'rb') as f:
  Person = pickle.load(f)
  aa = Person('gg', 23, '6')
  aa.work()

dic = {'age': 23, 'job': 'student'}
dic_str = json.dumps(dic)
print(type(dic_str), dic_str)
# out: <class 'str'> {"age": 23, "job": "student"}

dic_obj = json.loads(dic_str)
print(type(dic_obj), dic_obj)
# out: <class 'dict'> {'age': 23, 'job': 'student'}

dic = {'age': 23, 'job': 'student'}
with open('abc.json', 'w', encoding='utf-8') as f:
  json.dump(dic, f)

with open('abc.json', encoding='utf-8') as f:
  obj = json.load(f)
  print(obj)

aa = Person('Bob', 23, 'Student')
with open('abc.json', 'w', encoding='utf-8') as f:
  json.dump(aa, f) # 报错

def person2dict(person):
  return {'name': person.name,
      'age': person.age,
      'job': person.job}

print(aa.__dict) # {'name': 'Bob', 'age': 23, 'job': 'Student'}

def dict2person(dic):
  return Person(dic['name'], dic['age'], dic['job'])

with open('abc.json', 'w', encoding='utf-8') as f:
  json.dump(aa, f, default=person2dict)

with open('abc.json', encoding='utf-8') as f:
  obj = json.load(f, object_hook=dict2person)
  print(obj.name, obj.age, obj.job)
  obj.work()

with open('abc.json', 'w', encoding='utf-8') as f:
  json.dump(aa, f, default=lambda obj: obj.__dict__)

with shelve.open('aa') as f:
  f['person'] = {'age': 23, 'job': 'student'}
  f['person']['age'] = 44 # 这里试图改变原来的年龄23
  f['numbers'] = [i for i in range(10)]

with shelve.open('aa') as f:
  person = f['person']
  print(person) # {'age': 23, 'job': 'student'}
  nums = f['numbers']
  print(nums) # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

'person', (0, 44)
'numbers', (512, 28)

with shelve.open('aa', writeback=True) as f:
  dic = {'age': 23, 'job': 'student'}
  f['person'] = dic
  dic['age'] = 44
  f['person'] = dic

with shelve.open('aa') as f:
  f['class'] = Person
  
# 写入类本身
with shelve.open('aa') as f:
  Person = f['class']
  a = Person('Bob', 23, 'Student')
  a.work()

with shelve.open('aa') as f:
  a = Person('God', 100, 'watch')
  f['class'] = a

with shelve.open('aa') as f:
  god = f['class']
  god.work()