python3.6入门到高阶(全栈) day022 模块2 序列化

今日主要内容
    序列化 把对象打散成二进制字节 bytes
    1. pickle  把一个对象转化成bytes写入到文件( pickle序列化的内容是⼆进制的内容(bytes) 不是给⼈看的.)
        pickle.dumps() 把对象转换成bytes
        pickle.loads() 把bytes转化成对象

        pickle.dump() 把对象转换成bytes. 写入到文件
        pickle.load() 把文件中的bytes读取. 转化成对象

    例  import pickle
        class Fruit:
             def __init__(self,name,color):
                 self.name = name
                 self.color = color

             def eat(self):
                return "haochi"

        p1 = Fruit("apple1","red1")    # 赋值
        p2 = Fruit("apple2","red4")
        p3 = Fruit("apple3","red2")
        p4 = Fruit("apple4","red6")
        lst = [p1,p2,p3,p4]   # 装进一个列表

        pickle.dump(lst,open("fruit_info","wb"))   # 把对象转换成bytes. 写入到文件

        lst = pickle.load(open("fruit_info","rb"))  #  把文件中的bytes读取. 转化成对象
        for i in lst:    #  遍历这个对象
             print(i.name)   # 打印这个对象的 名字或者颜色



    2. shelve 小型数据库, redis, mongodb, dict
        当成字典来用
        writeback=True

    例 import shelve

        d = shelve.open("sylar") # 文件类型的字典
        d['wf'] = "汪峰"
        d.close()

        d = shelve.open("sylar")
        print(d['wf'])
        d.close()

        d = shelve.open("sylar") # 文件类型的字典
        d['wf'] = {"name":"汪峰", "age": 18, "wife":{"name":"章子怡", "hobby":"拍电影"}}
        d.close()

        d = shelve.open("sylar", writeback=True) # 文件类型的字典 wirteback把修改的内容自动的回写到文件中
        d['wf']['wife']['hobby'] = "当导师" #　改
        d.close()

        d = shelve.open("sylar") # 文件类型的字典
        print(d['wf'])
        d.close()

    3. json 以前用xml  先在用json    (ensure_ascii = False  可以处理中文)

        json.dumps() 把字典转换成json字符串
        json.loads() 把json字符串转化成字典

    例  字典转字符串
        import json
        dic = {"a": "⼥王", "b": "萝莉", "c": "⼩清新"}
        s = json.dumps(dic) # 把字典转化成json字符串
        print(s) # {"a": "u5973u738b", "b": "u841du8389", "c":
        "u5c0fu6e05u65b0"}
        s = json.dumps(dic, ensure_ascii=False) # 把字典转化成json字符串
        print(s) # {"a": "⼥王", "b": "萝莉", "c": "⼩清新"}
    例  字符串转字典
        s = '{"a": "⼥王", "b": "萝莉", "c": "⼩清新"}'
        dic = json.loads(s)
        print(type(dic), dic)

    例   数据量⼤的话,改⽤dumps和loads. 对每⼀⾏分别进⾏处理.
            import json
            lst = [{"a": 1}, {"b": 2}, {"c": 3}]
            # 写⼊
            f = open("test.json", mode="w", encoding="utf-8")
            for el in lst:
             s = json.dumps(el, ensure_ascii=True) + "
"
             f.write(s)
             f.close()
            # 读取
            f = open("test.json", mode="r", encoding="utf-8")
            for line in f:
             dic = json.loads(line.strip())
             print(dic)
             f.close()

        json.dump() 把字典转换成json字符串. 写入到文件
        json.load() 把文件中的json字符串读取. 转化成字典
        写入到⽂件中
        dic = {"a": "小萝莉", "b": "大萝莉", "c": "猥琐大叔", "d": False, "e": None, "wf":{"name":"半壁江山", "hobby":"皮裤"}}
        f = open("sylar.json", mode="w", encoding="utf-8")
        json.dump(dic, f, ensure_ascii=False, indent=4) # 4个空格 = 1个tab
        从⽂件中读取⼀个json
        f = open("sylar.json", mode="r", encoding="utf-8")
        d = json.load(f)
        print(d)

        default = 把对象转化成字典. 需要自己写转换过程
        object_hook = 把字典转化成对象. 需要自己写转换过程

    4. configparser 处理windows配置文件的  dict