import json

class user:
  def __init__(self, name, pwd):
    self.name = name
    self.pwd = pwd

  def __str__(self):
    return 'user(' + self.name + ',' + self.pwd + ')'

#重写JSONEncoder的default方法，object转换成dict
class userEncoder(json.JSONEncoder):
  def default(self, o):
    if isinstance(o, user):
      return {
        'name': o.name,
        'pwd': o.pwd
      }
    return json.JSONEncoder.default(o)

#重写JSONDecoder的decode方法，dict转换成object
class userDecode(json.JSONDecoder):
  def decode(self, s):
    dic = super().decode(s)
    return user(dic['name'], dic['pwd'])

#重写JSONDecoder的__init__方法，dict转换成object
class userDecode2(json.JSONDecoder):
  def __init__(self):
    json.JSONDecoder.__init__(self, object_hook=dic2objhook)


# 对象转换成dict
def obj2dict(obj):

  if (isinstance(obj, user)):
    return {
      'name': obj.name,
      'pwd': obj.pwd
    }
  else:
    return obj

# dict转换为对象
def dic2objhook(dic):

  if isinstance(dic, dict):
    return user(dic['name'], dic['pwd'])
  return dic

# 第一种方式，直接把对象先转换成dict
u = user('smith', '123456')
uobj = json.dumps(obj2dict(u))
print('uobj: ', uobj)


#第二种方式，利用json.dumps的关键字参数default
u = user('smith', '123456')
uobj2 = json.dumps(u, default=obj2dict)
print('uobj2: ', uobj)

#第三种方式，定义json的encode和decode子类，使用json.dumps的cls默认参数
user_encode_str = json.dumps(u, cls=userEncoder)
print('user2json: ', user_encode_str)

#json转换为object
u2 = json.loads(user_encode_str, cls=userDecode)
print('json2user: ', u2)

#另一种json转换成object的方式
u3 = json.loads(user_encode_str, cls=userDecode2)
print('json2user2: ', u3)

C:\python\python.exe C:/Users/Administrator/PycharmProjects/pytest/com/guo/myjson.py
uobj: {"name": "smith", "pwd": "123456"}
uobj2: {"name": "smith", "pwd": "123456"}
user2json: {"name": "smith", "pwd": "123456"}
json2user: user(smith,123456)
json2user2: user(smith,123456)

Process finished with exit code 0