24.序列化与反序列化

    1：序列化：简单来说就是将内存中的数据转换为字节序列保存到文件
    2：反序列化：将字节序列的文件中的内容恢复到内存中

    # 示例1：序列化写入文件
    import pickle
    lst = [1,2,3,4]
    dicty = {‘name‘: ‘Robby‘, ‘age‘: 27}
    with open(file=‘test.txt‘, mode=‘wb‘) as f:
        pickle.dump(lst, f)
        pickle.dump(dicty, f)
    with open(file=‘test.txt‘, mode=‘rb‘) as f:
        for line in f:
            print(line)
    # 示例2：序列化Python对象
    import pickle
    def add(x, y):
        print(x + y)
    class Add:
        def __init__(self):
            print(‘hello‘)
    serialise_obj1 = pickle.dumps(add)
    serialise_obj2 = pickle.dumps(Add)
    print(serialise_obj1)
    print(serialise_obj2)
    new_add = pickle.loads(serialise_obj1)
    new_Add = pickle.loads(serialise_obj2)
    print(new_add)
    print(new_Add)
    print(new_add(1,2))
    print(new_Add())
    # 示例3: 将序列化的函数写入文件，到另外一个模块中运行, 会报错，为什么? 
    文件1
    import pickle
    def add(x, y):
        print(x + y)
    with open(‘test.txt‘, ‘wb‘) as f:
        pickle.dump(add, f)
    文件2
    import pickle
    with open(‘test.txt‘, ‘rb‘) as f:
        new_function = pickle.load(f)  # AttributeError: Can‘t get attribute ‘add‘ on <module ‘__main__‘ from ‘/Users/yinhuanyi/Documents/XKD_Python_Course/first_chapter/other.py‘>
    文件2修改
    def add(x, y):
        print(x + y)
    import pickle
    with open(‘test.txt‘, ‘rb‘) as f:
        new_function = pickle.load(f)
        new_function(1,2)

    # json 跨语言的序列化方式，用于存储和展示数据
    {
        "name": "中国",
        "province": [{
            "name": "黑龙江",
            "cities": {
                "city": ["哈尔滨", "大庆"]
            }
        }, {
            "name": "广东",
            "cities": {
                "city": ["广州", "深圳", "珠海"]
            }
        }, {
            "name": "台湾",
            "cities": {
                "city": ["台北", "高雄"]
            }
        }, {
            "name": "新疆",
            "cities": {
                "city": ["乌鲁木齐"]
            }
        }]
    }
    # python 与 json对象的转化
    import json
    dictionary = {
        ‘name‘: ‘Robby‘,
        ‘age‘: 27
    }
    json_obj = json.dumps(dictionary)
    print(json_obj)
    new_dict = json.loads(json_obj)
    print(new_dict)
    # json.dump()和json.load() 是将json对象保存到文件

    # 需要先安装
    pip install msgpack-python
    # 示例
    import msgpack
    dictionary = {
        ‘name‘: ‘Robby‘,
        ‘age‘: 27
    }
    msgpack_obj = msgpack.packb(dictionary)
    print(msgpack_obj)
    new_dictionary = msgpack.unpackb(msgpack_obj, )
    print(new_dictionary)
    print(type(new_dictionary))