45 lines
1.4 KiB
Python
45 lines
1.4 KiB
Python
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import os.path
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import io
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# 这是一个缓存区写入函数，目的是新建一个内存缓冲区，并把指定文件的内容写入
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def read_info_buffer(filename):
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# 建立一个字节数组缓冲区
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buffer = bytearray(os.path.getsize(filename))
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with open(filename, 'rb') as file:
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file.readinto(buffer)
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return buffer
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if __name__ == '__main__':
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# with open('5.文件与IO/9.bin_file.bin', 'wb') as f:
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# f.write(b'Hello World')
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# 将文件内容写入缓冲区
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buf = read_info_buffer('5.文件与IO/9.bin_file.bin')
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print(buf)
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# 当然，缓冲区也可以有其他操作，比如切片
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buf[0: 5] = b'hello'
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print(buf)
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# 当我们访问一个大文件时，如果里面分为2个字节的多块，就可以这样干
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record_size = 2
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buf2 = bytearray(record_size)
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with open('5.文件与IO/9.bin_file.bin', 'rb') as f:
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while True:
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n = f.readinto(buf2)
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print(buf2)
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if n < record_size:
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break
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# 还有一个好玩的东西，内存映像memoryview，它允许我们直接操作对象的内存
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suka = bytearray(b'suka blyet')
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# 获取suka的内存地址
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m = memoryview(suka)
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# 将suka12~4位的地址给m2
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m2 = m[1:4]
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print(suka)
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# 对这些地址上的数据进行相应长度的修改
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m2[:] = b'abc'
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# 可以看到这时候suka已经发生了变化
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print(suka)
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