python之json的使用

json模块主要是序列化和反数列化数据的，主要有四个函数：  dumps、dump、loads、load

def dumps(obj, skipkeys=False, ensure_ascii=True, check_circular=True,
        allow_nan=True, cls=None, indent=None, separators=None,
        default=None, sort_keys=False, **kw):
    # Serialize ``obj`` to a JSON formatted ``str``.
    # 序列号 “obj” 数据类型 转换为 JSON格式的字符串

def dump(obj, fp, skipkeys=False, ensure_ascii=True, check_circular=True,
        allow_nan=True, cls=None, indent=None, separators=None,
        default=None, sort_keys=False, **kw):
    """Serialize ``obj`` as a JSON formatted stream to ``fp`` (a
    ``.write()``-supporting file-like object).
     我理解为两个动作，一个动作是将”obj“转换为JSON格式的字符串，还有一个动作是将字符串写入到文件中，也就是说文件描述符fp是必须要的参数 """

import json

dic = {'name': 'alvin', 'age': 23, 'sex': 'male'}
#效果一样
with open('db.json','w') as f:
    print(json.dump(dic,f)) # 没有返回值

with open('db1.json','w') as f:
    print(json.dumps(dic)) # 将序列化后的字符串形式的内容返回
    print(type(json.dumps(dic)))
    f.write(json.dumps(dic))

loads和load  反序列化方法

       loads 只完成了反序列化，

       load 只接收文件描述符，完成了读取文件和反序列化

def loads(s, encoding=None, cls=None, object_hook=None, parse_float=None, parse_int=None, parse_constant=None, object_pairs_hook=None, **kw):
    """Deserialize ``s`` (a ``str`` instance containing a JSON document) to a Python object.
       将包含str类型的JSON文档反序列化为一个python对象"""

def load(fp, cls=None, object_hook=None, parse_float=None, parse_int=None, parse_constant=None, object_pairs_hook=None, **kw):
    """Deserialize ``fp`` (a ``.read()``-supporting file-like object containing a JSON document) to a Python object.
        将一个包含JSON格式数据的可读文件饭序列化为一个python对象"""

import json
with open("db.json", "r", encoding='utf-8') as f:
    aa = json.loads(f.read())
    f.seek(0)
    bb = json.load(f)    # 与 json.loads(f.read())
print(aa)
print(bb)

#{'name': 'alvin', 'age': 23, 'sex': 'male'}
#{'name': 'alvin', 'age': 23, 'sex': 'male'}