day22 常用模块02 序列化

序列化 把对象打散成二进制字节 bytes,  方便对象的存储和传输

python中存在三种序列化方案: pikle , shelve, json

1. pickle  把一个对象转化成bytes写入到文件
    pickle.dumps() 把对象转换成bytes

import pickle

class Cat:
    def __init__(self, name, color):
        self.name = name
        self.color = color

    def chi(self):
        print("%s猫会吃老鼠" % self.name)

c = Cat("汪峰","黑色")

bs = pickle.dumps(c) # 把一个对象转化成bytes
print(bs)

    pickle.loads() 把bytes转化成对象

cc = pickle.loads(bs) # 把⼆进制反序列化成我们的对象
print(cc)

    pickle.dump() 把对象转换成bytes. 写入到文件

c1 = Cat("汪峰1","黑色")
c2 = Cat("汪峰2","黑色")
c3 = Cat("汪峰3","黑色")

lst = [c1, c2, c3]
f = open("cat.dat", mode="ab")
pickle.dump(lst, f) # 把对象写到文件中

    pickle.load() 把文件中的bytes读取. 转化成对象

f = open("cat.dat", mode="rb")
lst = pickle.load(f) # 从文件中读取第一次
for cc in lst:
    cc.chi()

记住一点: pikle序列化的内容是二进制内容(bytes), 不是给人看的


2. shelve 小型数据库, 当作dict使用  
shelve提供python的持久化操作, 即把数据写在硬盘上

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"    #  不能直接修改， 需要writeback配合
d.close()


d = shelve.open("sylar")
for k, v in d.items():
    print(k, v)    # wf {'name': '汪峰', 'age': 18, 'wife': {'name': '章子怡', 'hobby': '当导师'}}
print(type(d))      #<class 'shelve.DbfilenameShelf'>

3. json 以前用xml  先在用json
    json.dumps() 把字典转换成json字符串
    json.loads() 把json字符串转化成字典

    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

 ensure_ascii = False  可以处理中文

mport  json

# 准备一个字典
dic = {"a": "小萝莉", "b": "大萝莉", "c": "猥琐大叔", "d": False, "e": None}
# python中可以直接把字典或者列表转化成json
s = json.dumps(dic, ensure_ascii=False)  # pickle
print(type(s))  #  str
print(s)  # {"a": "小萝莉", "b": "大萝莉", "c": "猥琐大叔", "d": false, "e": null}  json的打印结果和python有区别

s = '{"a": "小萝莉", "b": "大萝莉", "c": "猥琐大叔", "d": false, "e": null}'
d = json.loads(s)   # 把json转化成字典
print(d)            #  {'a': '小萝莉', 'b': '大萝莉', 'c': '猥琐大叔', 'd': False, 'e': None}
print(type(d))  # dict
#
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

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

class Person:
    def __init__(self, firstName, lastName):
        self.firstName = firstName
        self.lastName = lastName

s = '{"firstName": "尼古拉斯", "lastName": "刘能"}'
def func(dic):
    return Person(dic['firstName'], dic["lastName"])

p = json.loads(s, object_hook=func) # 通过函数func把字典转换回对象
print(p.firstName, p.lastName)　　#尼古拉斯 刘能


p = Person("尼古拉斯", "刘能")
# 把对象转换成json
s = json.dumps(p.__dict__, ensure_ascii=False) # 方案一, 转的是字典
def func(obj):
    return {
        "firstName": obj.firstName,
        "lastName": obj.lastName
    }
s = json.dumps(p, default=func, ensure_ascii=False) # 方案二 转化的也是字典
print(s)　　#{"firstName": "尼古拉斯", "lastName": "刘能"}

f = open("movie.json", mode="r", encoding="utf-8")
dic1 = json.load(f)  # 当json文件中保存多个json的时候不能一次性全部都读取出来
print(dic1)

f = open("movie.json", mode="r", encoding="utf-8")
for line in f:
    line = line.strip()
    if line == "":  # 如果是空字符跳过
        continue
    else:
        d = json.loads(line)  # 一行一行的处理
        print(d)

4. configparser 处理windows配置文件的  dict

import configparser

config = configparser.ConfigParser() # 创建对象

config['DEFAULT'] = {  # 特殊
    "name":"腾讯qq木马",
    "time":"qq更新时间",
    "version":"1.0"
}
config['SERVER_1'] = {
    "IP":"192.168.1.123",
    "port":"12306"
}
config['SERVER_2'] = {
    "IP":"192.168.1.178",
    "port":"12311"
}
config['SERVER_3'] = {
    "IP":"192.168.1.176",
    "port":"12312"
}

# 写入到文件
config.write(open("qq.ini", mode="w", encoding="utf-8"))


# 读取内容
config = configparser.ConfigParser()
# 读取内容
config.read("qq.ini", encoding="utf-8") # 此时我们把文件中的内容读取到config
print(config['SERVER_1']['IP']) # 字典
print(config['SERVER_2']['name'])
print(config.get("SERVER_3", "IP")) # 字典

for k, v in config['DEFAULT'].items():
    print(k, v)