python笔记（pickle、cPickle模块） python

pickle包
1) 将内存中的对象转换成为文本流：

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import pickle# define class class Contact(object): def __init__(self, uid, name, age):

self.uid = uid

self.age = age

self.name = name

c = Contact(1001,'aaa',25)

ps = pickle.dumps(c)#转换成字符串

c_copy = pickle.loads(ps) #转换成对象

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使用pickle.dumps()方法可以将对象c转换成了字符串
当然，我们也可以使用pickle.dump()的方法，将上面两部合二为一:

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import pickle

class Contact(object): def __init__(self, uid, name, age):

self.uid = uid

self.age = age

self.name = name

c = Contact(1005)with open('./tmp.data', 'w') as f:
ps = pickle.dump(summer, f)

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对象c存储在文件ymp.data
【python笔记（pickle、cPickle模块）】
2) 重建对象
首先，我们要从文本中读出文本，存储到字符串 (文本文件的输入输出)。然后使用pickle.loads(str)的方法，将字符串转换成为对象。要记得，此时我们的程序中必须已经有了该对象的类定义。

此外，我们也可以使用pickle.load()的方法，将上面步骤合并:

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import pickle

class Contact(object): def __init__(self, uid, name, age):

self.uid = uid

self.age = age

self.name = name

fn = ' ./tmp.data ' with open(fn, ' r ' ) as f: summer = pickle.load(f)

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cPickle包
cPickle包的功能和用法与pickle包几乎完全相同 (其存在差别的地方实际上很少用到)，不同在于cPickle是基于c语言编写的，速度是pickle包的1000倍。对于上面的例子，如果想使用cPickle包，我们都可以将import语句改为:

import cPickle as pickle

就不需要再做任何改动了。
下面时存储数据的小实例：
contact.py

#!/usr/bin/env python #-*- coding:utf-8 -*-import copy import jsonimport base__all__ = ['Contact']class Contact(base.Base): '''联系人''' DEBUG = Truedef __init__(self, **kwargs): self.init(**kwargs)def init(self, **kwargs): self.uid = kwargs.pop('uid', 0) self.name = kwargs.pop('name', '') self.age = kwargs.pop('age', 0) self.addr = kwargs.pop('addr','') self.phone = kwargs.pop('phone', '') self.ext = json.loads(kwargs.pop('ext', '{}'))def __str__(self): return "id:%s,uid:%s,name:%s,age:%s,%s"%(id(self), self.uid,self.name, self.age,','.join(['%s:%s'%(k,v) for k, v in self.ext.iteritems()]))def __getattr__(self, k): if Contact.DEBUG: print 'in Contact __getattr__ %s'%k return self.ext.get(k)def get_key(self): return self.uiddef changed(self): if getattr(self, 'manager'): self.manager.changed = Truedef set_age(self, age): assert type(age)==int, 'age must be interge' self.age = age self.changed() def set_uid(self, uid): assert type(uid)==int, 'uid must be interge' self.uid = uid self.changed()def set_name(self, name): assert type(name)==str, 'name must be string' self.name = name self.changed()def load(self, **kwargs): return self.init(**kwargs)def save(self): m = self.__dict__.pop('manager', None) data = https://www.it610.com/article/copy.deepcopy(self.__dict__) self.manager = m data['ext'] = json.dumps(data['ext']) return data

loader.py

#!/usr/bin/env python #-*- coding:utf-8 -*-import os import sys import cPickleclass Loader(object): '''cPickle loader'''def __init__(self, filename=None): self.filename = filenamedef load(self, filename=None): data = https://www.it610.com/article/[] filename = filename or self.filename try: with open(filename or self.filename,'r') as fd: data = https://www.it610.com/article/cPickle.load(fd) except: print'load data failed' return datadef save(self, data, filename=None): assert (filename or self.filename), 'give a filename to save data' try: with open(filename or self.filename, 'w') as fd: cPickle.dump(data, fd) except: return False return True

manager.py

#!/usr/bin/env python #-*- coding:utf-8 -*-class Manager(object): '''联系人管理类''' def __init__(self, memclass, loader, condition=None): '''''' self.changed = False self.loader = loader self.memclass = memclass self.member = self.loader.load(condition) if condition else {}def add_mem(self, memobj): okey = memobj.get_key() if okey in self.member: return False memobj.manager = self

self.changed = True self.member[okey] = memobj return Truedef del_mem(self, memobj=None, mkey=None): obj = None if memobj: obj = self.member.pop(memobj.get_key(), None) if mkey: obj = self.member.pop(mkey, None) if obj:

obj.manager = None

return obj def find_mem(self, mkey): return self.member.get(mkey, None)def load(self, condition=None): assert not self.changed, "the member is not null, you should save first" data = self.loader.load(condition) for e in data: if isinstance(e, self.memclass): memobj = e else: memobj = self.memclass(**e) memobj.manager = self self.member[memobj.get_key()] = memobjdef save(self): if self.changed: data = [] for _, memobj in self.member.iteritems(): data.append(memobj.save()) self.loader.save(data) self.changed = Falsedef display(self): for _, m in self.member.iteritems(): print m

main.py

#!/usr/bin/env python #-*- coding:utf-8 -*-import contact import loader import managerdef main(): tmp_loader = loader.Loader('./tmp.data') tmp_manager = manager.Manager(contact.Contact, tmp_loader) tmp_contact = contact.Contact() tmp_contact.set_uid(1001) tmp_contact.set_age(25) tmp_contact.set_name('nnn') tmp_manager.add_mem(tmp_contact) tmp_manager.save()if __name__=='__main__': main()