python 字符串IO

io.StringIO

s = io.StringIO()
s.write('Hello World\n')
12
print('This is a test', file=s)
15

Get all of the data written so far

s.getvalue()
'Hello World\nThis is a test\n'

Wrap a file interface around an existing string

s = io.StringIO('Hello\nWorld\n')
s.read(4)
'Hell'
s.read()
'o\nWorld\n'

s = io.BytesIO()
s.write(b'binary data')
s.getvalue()
b'binary data'