如何进行虚拟文件处理？

因此，对于创建文件，我使用以下方法:

fileHandle = open('fileName', 'w')

然后将内容写入文件，关闭文件。 在下一步中，我处理这个文件。 在程序结束时，我得到了一个需要删除的“物理文件”。

有没有一种方法可以编写一个“虚拟”文件，它的行为与“物理”文件完全一样(允许以相同的方式操作它) ，但在 Python 运行结束时不存在？

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小开

You have StringIO and BytesIO in the io module.

StringIO behaves like a file opened in text mode - reading and writing unicode strings (equivalent to opening a file with io.open(filename, mode, encoding='...')), and the BytesIO behaves like a file opened in binary mode (mode='[rw]b'), and can read write bytes.

Python 2:

In [4]: f = io.BytesIO('test')
In [5]: type(f.read())
Out[5]: str
In [6]: f = io.StringIO(u'test')
In [7]: type(f.read())
Out[7]: unicode

Python 3:

In [2]: f = io.BytesIO(b'test')
In [3]: type(f.read())
Out[3]: builtins.bytes
In [4]: f = io.StringIO('test')
In [5]: type(f.read())
Out[5]: builtins.str
小开

You can use StringIO as a virtual file , from official documentation 

from io import StringIO


output = StringIO()
output.write('First line.\n')
print >>output, 'Second line.'


# Retrieve file contents -- this will be
# 'First line.\nSecond line.\n'
contents = output.getvalue()


# Close object and discard memory buffer --
# .getvalue() will now raise an exception.
output.close()
小开

There is the StringIO module, read its documentation, it should be easy to use.

Bear in mind, though, that this would keep the "file's" contents in memory. If you have too much data, it would probably be better to create a real file, e.g. in /tmp, and delete it afterwards.

小开
最佳答案

You might want to consider using a tempfile.SpooledTemporaryFile which gives you the best of both worlds in the sense that it will create a temporary memory-based virtual file initially but will automatically switch to a physical disk-based file if the data held in memory exceeds a specified size.

Another nice feature is that (when using memory) it will automatically use either an io.BytesIO or io.StringIO depending on what mode is being used—allowing you to either read and write Unicode strings or binary data (bytes) to it.

The only tricky part might be the fact that you'll need to avoid closing the file between steps because doing so would cause it to be deleted from memory or disk. Instead you can just rewind it back to the beginning with a file seek(0) method call.

When you are completely done with the file and close it, it will automatically be deleted from disk if the amount of data in it caused it to be rolled-over to a physical file.

小开

If you mean writing to memory instead of a file, you can simply write the text to a buffer and use the following function:

def write(text):
global buffer
buffer += text + '\n'  # Add a linefeed as you would if you were writing to a file


buffer = ""  # Initialize the buffer
write("My name is Steve Grafton")

At the end, you will have a buffer that will be the same as if you had written your stuff to a file and then open the file and read all its contents to a buffer! Moreover, you can use the buffer during the process (before having finished your writing) and do searches in it, as if you had created a file for both reading and writing, only that in this case your pointer will


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