说明

它实现了一个工作在内存的文件对象(内存文件). 在大多需要标准文件对象的地方都可以使用它来替换.

例子

1. 从内存文件读入内容

   from io import StringIO
   message = 'That man is depriving a village somewhere of a computer scientist.'
   file = StringIO(message)
   print(file.read())
   >>That man is depriving a village somewhere of a computer scientist.

2. 使用getvalue方法用来返回内部的字符串值

   from io import StringIO
   file = StringIO()
   file.write("This man is no ordinary man.")
   print(file.getvalue())
   >>This man is no ordinary man.

3. 使用StringIO捕获输出

   from io import StringIO
   import sys
   s1 = '23131'
   n = 12
   v = 13
   old_stdout = sys.stdout
   file = StringIO()
   sys.stdout = file
   print(s1,n,v)
   sys.stdout = old_stdout
   print(file.getvalue())
   >>23131 12 13

   cStringIO

是一个可选的模块, 是 StringIO 的更快速实现. 它的工作方式和 StringIO 基本相同, 但是它不可以被继承，在python3中被废除

import cStringIO
MESSAGE = "That man is depriving a village somewhere of a computer scientist."
file = cStringIO(MESSAGE)
print(file.read())