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写文件时如何限制文件大小?

file-io python

Alex Amato · 技术社区 · 15 年前

我正在使用IO模块的输出流并写入文件。我希望能够检测到何时我已经将1g数据写入了一个文件,然后开始写入第二个文件。我似乎不知道如何确定我已写入文件的数据量。

有什么容易内置的吗 io ?或者我可能需要在每次手动写入之前计算字节数?

6 回复 | 直到 8 年前

Mark Tolonen 15 年前

File Objects tell

>>> f=open('test.txt','w')
>>> f.write(10*'a')
>>> f.tell()
10L
>>> f.write(100*'a')
>>> f.tell()
110L

Tom Wainwright 12 年前

RotatingFileHandler

import logging
import logging.handlers

file_name = 'test.log'

test_logger = logging.getLogger('Test')
handler = logging.handlers.RotatingFileHandler(file_name, maxBytes=10**9)
test_logger.addHandler(handler)

janneb 15 年前

martineau 12 年前

file

'\n' '\r\n' bufsize file() open()

import os.path
verbose = False

class LtdSizeFile(file):
    ''' A file subclass which  limits size of file written to approximately "maxsize" bytes '''
    def __init__(self, filename, mode='wt', maxsize=None):
        self.root, self.ext = os.path.splitext(filename)
        self.num = 1
        self.size = 0
        if maxsize is not None and maxsize < 1:
            raise ValueError('"maxsize: argument should be a positive number')
        self.maxsize = maxsize
        file.__init__(self, self._getfilename(), mode)
        if verbose: print 'file "%s" opened' % self._getfilename()

    def close(self):
        file.close(self)
        self.size = 0
        if verbose: print 'file "%s" closed' % self._getfilename()

    def write(self, text):
        lentext =len(text)
        if self.maxsize is None or self.size+lentext <= self.maxsize:
            file.write(self, text)
            self.size += lentext
        else:
            self.close()
            self.num += 1
            file.__init__(self, self._getfilename(), self.mode)
            if verbose: print 'file "%s" opened' % self._getfilename()
            self.num += 1
            file.write(self, text)
            self.size += lentext

    def writelines(self, lines):
        for line in lines:
            self.write(line)

    def _getfilename(self):
        return '{0}{1}{2}'.format(self.root, self.num if self.num > 1 else '', self.ext)

if __name__=='__main__':
    import random
    import string

    def randomword():
        letters = []
        for i in range(random.randrange(2,7)):
            letters.append(random.choice(string.lowercase))
        return ''.join(letters)

    def randomsentence():
        words = []
        for i in range(random.randrange(2,10)):
            words.append(randomword())
        words[0] = words[0].capitalize()
        words[-1] = ''.join([words[-1], '.\n'])
        return ' '.join(words)

    lsfile = LtdSizeFile('LtdSizeTest.txt', 'wt', 100)
    for i in range(100):
        sentence = randomsentence()
        if verbose: print '  writing: {!r}'.format(sentence)
        lsfile.write(sentence)

    lsfile.close()

Corbin 15 年前

tell() if tell() > 1024*1024*1024:

if len(data_to_write) + tell > 1024*1024*1024:

Jeff Ferland 15 年前

tell()

#pseudocode
if (written + sizeOfNew > 1G) {
    rotateFile()
}