json实现实例化对象的存与读

import json
class A:
    def __init__(self,type,num):
        self.type=type
        self.num=num
    def welcome(self):
        print('how are you!')
class My_json:
    def __init__(self,filepath):
        self.file=filepath
    def json_dump(self,obj):
        with open(self.file,mode='a',encoding='utf-8') as f:
                s=json.dumps(obj)
                f.write(f'{s}
')
    def json_load(self):
        with open(self.file,mode='r',encoding='utf-8') as f:
            for i in f:
                i=json.loads(i.strip())
a=A('cat',1).__dict__
s=My_json('file')
s.json_dump(a)
s.json_load()