java io

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1B = 8b (bit比特)
1KB = 2^bai10(2的du10次方) B= 1024B (Byte字节)
1MB = 2^10KB = 1024K
1GB = 2^10MB = 1024MB
1TB = 2^10GB = 1024GB
1PB = 2^10TB = 1024TB