具有惯用Scala的人类可读格式的字节

Question

我正在寻找惯用的Scala代码，该代码将许多字节格式化为人类可读的字符串，这在向用户显示文件大小时非常有用。

例如，应将1000字节格式化为1.0 kB，将49134421234字节格式化为49.1 GB。

格式化功能的一些要求：

• 尽可能的易读易懂
• 适用于SI（例如兆字节）和IEC单位（例如兆字节）
• 不依赖外部库
• 可通过Scala.js在浏览器中执行

Answer 1

我的版本：

/**
  * Converts a number of bytes into a human-readable string
  * such as `2.2 MB` or `8.0 EiB`.
  *
  * @param bytes the number of bytes we want to convert
  * @param si    if true, we use base 10 SI units where 1000 bytes are 1 kB.
  *              If false, we use base 2 IEC units where 1024 bytes are 1 KiB.
  * @return the bytes as a human-readable string
  */
def humanReadableSize(bytes: Long, si: Boolean): String = {

  // See https://en.wikipedia.org/wiki/Byte
  val (baseValue, unitStrings) =
    if (si)
      (1000, Vector("B", "kB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"))
    else
      (1024, Vector("B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB"))

  def getExponent(curBytes: Long, baseValue: Int, curExponent: Int = 0): Int =
    if (curBytes < baseValue) curExponent
    else {
      val newExponent = 1 + curExponent
      getExponent(curBytes / (baseValue * newExponent), baseValue, newExponent)
    }

  val exponent = getExponent(bytes, baseValue)
  val divisor = Math.pow(baseValue, exponent)
  val unitString = unitStrings(exponent)

  // Divide the bytes and show one digit after the decimal point
  f"${bytes / divisor}%.1f $unitString"
}

用法示例：

// Result: 1.0 kB
humanReadableSize(1000, si = true)

// Result: 1000.0 B
humanReadableSize(1000, si = false)

// Result: 10.0 kB
humanReadableSize(10000, si = true)

// Result: 9.8 KiB
humanReadableSize(10000, si = false)

// Result: 49.1 GB
humanReadableSize(49134421234L, si = true)

// Result: 45.8 GiB
humanReadableSize(49134421234L, si = false)