27-1 序列化模块 pickle

python专用

没什么限制

能处理很多数据类型！

dump 需要的文件f句柄 需要wb形式打开，load需要rb模式

支持对象序列化！需要这个对象对应的类在内存中

转成bytes类型！也是序列类型

dic = {1:(12,3,4),('a','b'):4}
import pickle

pic_dic = pickle.dumps(dic)
print(pic_dic)    # bytes类型  b'x80x04x95x1bx00x00x00x.... 
new_dic = pickle.loads(pic_dic)
print(new_dic)    # {1: (12, 3, 4), ('a', 'b'): 4}

支持几乎所有对象的

class Student:
    def __init__(self,name,age):
        self.name = name
        self.age = age

alex = Student('alex',83)
ret = pickle.dumps(alex)
小花 = pickle.loads(ret)
print(小花.name)  
print(小花.age)

class Student:
    def __init__(self,name,age):
        self.name = name
        self.age = age

alex = Student('alex',83)
with open('pickle_demo','wb') as f:
    pickle.dump(alex,f)
with open('pickle_demo','rb') as f:
    旺财 = pickle.load(f)
    print(旺财.name)

这种方式可以重复写入，然后重复拿出来（这里有一个异常，在最后一次没有值，会报错，这里用了异常处理）

with open('pickle_demo','wb') as f:
    pickle.dump({'k1':'v1'}, f)
    pickle.dump({'k11':'v1'}, f)
    pickle.dump({'k11':'v1'}, f)
    pickle.dump({'k12':[1,2,3]}, f)
    pickle.dump(['k1','v1','l1'], f)

with open('pickle_demo','rb') as f:
    while True:
        try:
            print(pickle.load(f))
        except EOFError:
            break