import pickle   # 引入模块

class Cat:      # 创建类

    def __init__(self, name, age):

        self.name = name

        self.age = age

    def catch_mouse(self):

        print(self.name, "抓老鼠")

cat = Cat("jerry", 18)    # 创建一个对象

byte = pickle.dumps(cat)  # dumps()方法 --> 序列化一个对象

print(byte)               # 打印结果是一堆很长的二进制字符串

new_cat = pickle.loads(byte)    # 把二进制字符串反序列化为原来的对象

new_cat.catch_mouse()           # 执行结果: jerry 抓老鼠 --> 反序列化之后得到的对象还是原来那个类型的对象

import pickle

class Cat:

    def __init__(self, name, age):

        self.name = name

        self.age = age

    def catch_mouse(self):

        print(self.name, "抓老鼠")

cat = Cat("jerry", 18)      # 创建一个对象

with open("cat", mode="wb") as f:

    pickle.dump(cat, f)     # 把对象cat以二进制字符串的形式写进文件中

with open("cat", mode="rb") as f:

    new_cat = pickle.load(f)    # 从文件中读取信息,并把信息反序列化为对象

    new_cat.catch_mouse()       # 对象可以访问类中的方法

import pickle

class Cat:

    def __init__(self, name, age):

        self.name = name

        self.age = age

    def catch_mouse(self):

        print(self.name, "抓老鼠")

lst = [Cat("jerry", 19), Cat("tommy", 20), Cat("kendy", 21)]

with open("cat", mode="wb") as f:

    for el in lst:

        pickle.dump(el, f)      # 把对象序列化并写入文件

with open("cat", mode="rb") as f:

for i in range(len(lst)):       # 我们可能事先不知道列表中到底有多少个对象

    new_cat = pickle.load(f)    # 把文件中的二进制反序列化为对象

    new_cat.catch_mouse()       # 对象访问catch_mouse()方法

import pickle

class Cat:

    def __init__(self, name, age):

        self.name = name

        self.age = age

    def catch_mouse(self):

        print(self.name, "抓老鼠")

lst = [Cat("jerry", 19), Cat("tommy", 20), Cat("cendy", 21)]

with open("cat", mode="wb") as f:

    pickle.dump(lst, f)             # 直接把整个列表序列化并写进文件中

with open("cat", mode="rb") as f:

    new_lst = pickle.load(f)        # 读取文件中的信息,并将其反序列化,拿到一个列表

    for el in new_lst:              # 遍历整个列表

        el.catch_mouse()            # 每一个元素都可以访问catch_mouse()方法

import pickle

dic1 = {(1, 2, 3):{'a', 'b'}, 1:'abc'}

dic2 = {(1, 2, 3):{'a', 'b'}, 2:'abc'}

dic3 = {(1, 2, 3):{'a', 'b'}, 3:'abc'}

dic4 = {(1, 2, 3):{'a', 'b'}, 4:'abc'}

with open ("pickle_file", "wb") as f:

    pickle.dump(dic1, f)

    pickle.dump(dic2, f)

    pickle.dump(dic3, f)

    pickle.dump(dic4, f)

# 第一种读取方式:

with open("pickle_file", "rb") as f:

    ret = pickle.load(f)

    print(ret, type(ret))

    ret = pickle.load(f)

    print(ret, type(ret))

    ret = pickle.load(f)

    print(ret, type(ret))

    ret = pickle.load(f)

    print(ret, type(ret))

    # ret = pickle.load(f)    # EOFError: Ran out of input

    # print(ret, type(ret))   # 如果文件中的对象已经全部被load(拿出来反序列化)了,此时再次load就会报错

# 以上代码执行结果:

# {(1, 2, 3): {'b', 'a'}, 1: 'abc'} <class 'dict'>

# {(1, 2, 3): {'b', 'a'}, 2: 'abc'} <class 'dict'>

# {(1, 2, 3): {'b', 'a'}, 3: 'abc'} <class 'dict'>

# {(1, 2, 3): {'b', 'a'}, 4: 'abc'} <class 'dict'>

# 改进后的第二种读取方式:

with open("pickle_file", "rb") as f:

    while True:

        try:

            ret = pickle.load(f)

            print(ret, type(ret))

        except EOFError:        # 异常被捕获了

            break

import shelve

helf = shelve.open("shelve_test1")

# print(shelf["jay"])      # 报错,因为文件中还没有"jay"的信息

shelf["jay"] = "周杰伦"    # 执行新增

print(shelf["jay"])        # 打印结果: 周杰伦 --> 新增成功

shelf.close()

import shelve

shelf = shelve.open("shelve_test1")

print(shelf["jay"])

# 像操作字典一样直接进行修改:

shelf["jay"] = {"name": "周杰伦", "age": 18, "hobby": "唱歌"}

print(shelf["jay"])

shelf.close()

# 执行结果:

# 周杰伦

# {'name': '周杰伦', 'age': 18, 'hobby': '唱歌'}

尝试修改{'name': '周杰伦', 'age': 18, 'hobby': '唱歌'}这个字典中的内容:

shelf = shelve.open("shelve_test1")

shelf["jay"]["name"] = "王力宏"     # 尝试修改

shelf.close()

shelf = shelve.open("shelve_test1")

print(shelf["jay"]["name"])         # 查看我们修改的内容

shelf.close()

# 打印结果: 周杰伦 --> 修改失败

shelf = shelve.open("shelve_test1", writeback=True)

shelf["jay"]["name"] = "王力宏"     # 再次尝试修改

shelf.close()

shelf = shelve.open("shelve_test1")

print(shelf["jay"]["name"])         # 查看我们修改的内容

shelf.close()

# 打印结果: 王力宏 --> 修改成功

shelf = shelve.open("shelve_test1", writeback=True)

del shelf["jay"]

shelf.close()

shelf = shelve.open("shelve_test1")

print(shelf["jay"])     # 打印结果: 报错 --> 因为之前已经把"jay"的数据给删除了

shelf.close()

shelf = shelve.open("shelve_test1", writeback=True)

shelf["乐坛半壁江山"] = "汪峰"

shelf["华仔"] = "刘德华"

shelf["星爷"] = "周星驰"

shelf.close()

# 遍历文件拿到所有key

shelf = shelve.open("shelve_test1")

for k in shelf:

    print(k)        # 拿到所有key

for k in shelf.keys():

    print(k)        # 拿到所有key

for v in shelf.values():

    print(v)        # 拿到所有value

for k, v in shelf.items():

    print(k, v)     # 拿到所有key和value

shelf.close()