.xls 文件如下:

The hex signature for an .xls file is the following:

Excel电子表格子标题(MS Office)

Excel spreadsheet subheader (MS Office)

09 08 10 00 00 06 05 00 [512 byte offset]

您可以在***上了解其他各种签名.

You can read about the other various signatures on Wikipedia.

我相信您可以做这样的事情.这未经测试，但是您可以摆弄它直到它起作用.如果有任何建议或更改，请留下评论.谢谢！

I believe that you can do something like this. This is untested, but you can fiddle around with it until it works. Please leave comments for any suggestions or changes. Thanks!

xls_sig = b'\x09\x08\x10\x00\x00\x06\x05\x00'
offset = 512
size = 8

with open('spreadsheet.xls', 'rb') as f:
    f.seek(offset)       # Seek to the offset.
    bytes = f.read(size) # Capture the specified number of bytes.

    if bytes == xls_sig:
        print 'Uploaded file is an xls.'
    else:
        print 'File is not an xls.'

更新1

对此进行了测试，我可以验证它是否可以检测.xls文件.

我开发了一个程序来确定文件是xls还是xlsx:

I developed a program to determine if the file is an xls or xlsx:

import codecs

xlsx_sig = b'\x50\x4B\x05\06'
xls_sig = b'\x09\x08\x10\x00\x00\x06\x05\x00'

filenames = [
    ('spreadsheet.xls', 0, 512, 8),
    ('spreadsheet.xlsx', 2, -22, 4)]

for filename, whence, offset, size in filenames:
    with open(filename, 'rb') as f:
        f.seek(offset, whence) # Seek to the offset.
        bytes = f.read(size)   # Capture the specified number of bytes.

        print codecs.getencoder('hex')(bytes)

        if bytes == xls_sig:
            msg = '"{}" is an xls.'
        elif bytes == xlsx_sig:
            msg = '"{}" is an xlsx.'
        else:
            msg = '"{}" is not an Excel document.'
        print msg.format(filename)

这是输出:

('0908100000060500', 8)
"spreadsheet.xls" is an xls.
('504b0506', 4)
"spreadsheet.xlsx" is an xlsx.