Python学习日记－2

＊使用pickle处理数据存储，类似于java中的serialization，是将对象转化为二进制码存入文件中，主要函数pickle.dump(obj,file),pickle.load(file)

＊在每个文件加入后缀.pkl，实现逐行数据存入

＊使用shelve，实现dictionary数据的隐形固态存储，具体实现方式与pickle相同

import pickle
dbfile=open('people-pickle','wb')    #二进制写
pickle.dump(db, dbfile)
dbfile.close()

dbfile=open('people-pickle','rb')    ＃二进制读
db=pickle.load(dbfile)
print db

import pickle
for (key, record) in [('bob', bob), ('tom', tom), ('sue', sue)]:
    recfile = open(key + '.pkl', 'wb')
    pickle.dump(record, recfile)
    recfile.close()

import pickle, glob
for filename in glob.glob('*.pkl'):  ＃当前文件夹中所有以.pkl为后缀的文件
    recfile = open(filename, 'rb')
    record = pickle.load(recfile)
    print(filename, '=>\n ', record)
suefile = open('sue.pkl', 'rb')
print(pickle.load(suefile)['name'])

import shelve
db = shelve.open('people-shelve')
db['bob'] = bob
db['sue'] = sue
db.close()

db = shelve.open('people-shelve')
sue=db['sue']
sue['name']='Susie Q' #不能直接赋值给db['sue']['name']
db['sue']=sue
db.close

db = shelve.open('people-shelve')
print db
db.close()