6.3.3 使用 shelve 模块操作二进制文件

　　Python标准库shelve也提供了二进制文件操作的功能，可以像字典赋值一样来写入二进制文件，也可以像字典一样读取二进制文件，有点类似于NoSQL数据库MongoDB。

import shelve

fp = shelve.open('shelve_test.dat')  #创建或打开二进制文件

zhangsan = {'age':38,'sex':'Male','address':'SDIBT'}

fp['zhangsan'] = zhangsan   #往文件里写入内容

lisi = {'age':40,'sex':'Male','qq':'','tel':''}

fp['lisi'] = lisi

fp.close()

f = shelve.open('shelve_test.dat')

print(fp['zhangsan']['age'])

print(fp['lisi']['qq'])

fp.close()

===========执行报错如下

Traceback (most recent call last):

  File "C:\Users\dddd\AppData\Local\Programs\Python\Python35\lib\shelve.py", line 111, in __getitem__

    value = self.cache[key]

KeyError: 'zhangsan'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):

  File "C:/Users/dddd/AppData/Local/Programs/Python/Python35/test1.py", line 13, in <module>

    print(fp['zhangsan']['age'])

  File "C:\Users\dddd\AppData\Local\Programs\Python\Python35\lib\shelve.py", line 113, in __getitem__

    f = BytesIO(self.dict[key.encode(self.keyencoding)])

  File "C:\Users\dddd\AppData\Local\Programs\Python\Python35\lib\shelve.py", line 70, in closed

    raise ValueError('invalid operation on closed shelf')

ValueError: invalid operation on closed shelf

#在Pycharm 上就报这个错，暂时不知道如何解决

 >>> import shelve

 >>> fp=shelve.open('shelve.dat')

 >>> zhangsan = {'age':38,'sex':'Male'}

 >>> fp['zhangsan'] = zhangsan

 >>> fp.close

 >>> f = shelve.open('shelve_test.dat')

 >>> fp['zhangsan']['age']

 38

 >>>