如何在Java中将字节大小转换为人类可读的格式?
比如1024应该变成“1 Kb”，1024*1024应该变成“1 Mb”。
我有点厌倦了为每个项目写这个实用方法。在Apache Commons中有这样的静态方法吗?
当前回答
这是aioobe答案的修改版本。
变化:
Locale参数，因为有些语言使用。其他的，作为小数点。 人类可读的代码
private static final String[] SI_UNITS = { "B", "kB", "MB", "GB", "TB", "PB", "EB" };
private static final String[] BINARY_UNITS = { "B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB" };
public static String humanReadableByteCount(final long bytes, final boolean useSIUnits, final Locale locale)
{
final String[] units = useSIUnits ? SI_UNITS : BINARY_UNITS;
final int base = useSIUnits ? 1000 : 1024;
// When using the smallest unit no decimal point is needed, because it's the exact number.
if (bytes < base) {
return bytes + " " + units[0];
}
final int exponent = (int) (Math.log(bytes) / Math.log(base));
final String unit = units[exponent];
return String.format(locale, "%.1f %s", bytes / Math.pow(base, exponent), unit);
}
其他回答
FileUtils。如果你的项目依赖于org.apache.commons.io, byteCountToDisplaySize(长尺寸)可以工作。
此方法的JavaDoc
这是aioobe答案的修改版本。
变化:
Locale参数，因为有些语言使用。其他的，作为小数点。 人类可读的代码
private static final String[] SI_UNITS = { "B", "kB", "MB", "GB", "TB", "PB", "EB" };
private static final String[] BINARY_UNITS = { "B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB" };
public static String humanReadableByteCount(final long bytes, final boolean useSIUnits, final Locale locale)
{
final String[] units = useSIUnits ? SI_UNITS : BINARY_UNITS;
final int base = useSIUnits ? 1000 : 1024;
// When using the smallest unit no decimal point is needed, because it's the exact number.
if (bytes < base) {
return bytes + " " + units[0];
}
final int exponent = (int) (Math.log(bytes) / Math.log(base));
final String unit = units[exponent];
return String.format(locale, "%.1f %s", bytes / Math.pow(base, exponent), unit);
}
如果你使用Android，你可以简单地使用Android .text.format. formatter . formatfilesize()。它的优点是易于使用，并且它取决于区域设置，以便为用户更好地显示它。缺点是它不处理EB，而且它只用于公制单位(每个Kilo是1000字节，不能作为1024字节使用)。
或者，这里有一个基于这篇热门文章的解决方案:
interface BytesFormatter {
/**called when the type of the result to format is Long. Example: 123KB
* @param unitPowerIndex the unit-power we need to format to. Examples: 0 is bytes, 1 is kb, 2 is mb, etc...
* available units and their order: B,K,M,G,T,P,E
* @param isMetric true if each kilo==1000, false if kilo==1024
* */
fun onFormatLong(valueToFormat: Long, unitPowerIndex: Int, isMetric: Boolean): String
/**called when the type of the result to format is Double. Example: 1.23KB
* @param unitPowerIndex the unit-power we need to format to. Examples: 0 is bytes, 1 is kb, 2 is mb, etc...
* available units and their order: B,K,M,G,T,P,E
* @param isMetric true if each kilo==1000, false if kilo==1024
* */
fun onFormatDouble(valueToFormat: Double, unitPowerIndex: Int, isMetric: Boolean): String
}
/**
* formats the bytes to a human readable format, by providing the values to format later in the unit that we've found best to fit it
*
* @param isMetric true if each kilo==1000, false if kilo==1024
* */
fun bytesIntoHumanReadable(
@IntRange(from = 0L) bytesToFormat: Long, bytesFormatter: BytesFormatter,
isMetric: Boolean = true
): String {
val units = if (isMetric) 1000L else 1024L
if (bytesToFormat < units)
return bytesFormatter.onFormatLong(bytesToFormat, 0, isMetric)
var bytesLeft = bytesToFormat
var unitPowerIndex = 0
while (unitPowerIndex < 6) {
val newBytesLeft = bytesLeft / units
if (newBytesLeft < units) {
val byteLeftAsDouble = bytesLeft.toDouble() / units
val needToShowAsInteger =
byteLeftAsDouble == (bytesLeft / units).toDouble()
++unitPowerIndex
if (needToShowAsInteger) {
bytesLeft = newBytesLeft
break
}
return bytesFormatter.onFormatDouble(byteLeftAsDouble, unitPowerIndex, isMetric)
}
bytesLeft = newBytesLeft
++unitPowerIndex
}
return bytesFormatter.onFormatLong(bytesLeft, unitPowerIndex, isMetric)
}
Sample usage:
// val valueToTest = 2_000L
// val valueToTest = 2_000_000L
// val valueToTest = 2_000_000_000L
// val valueToTest = 9_000_000_000_000_000_000L
// val valueToTest = 9_200_000_000_000_000_000L
val bytesToFormat = Random.nextLong(Long.MAX_VALUE)
val bytesFormatter = object : BytesFormatter {
val numberFormat = NumberFormat.getNumberInstance(Locale.ROOT).also {
it.maximumFractionDigits = 2
it.minimumFractionDigits = 0
}
private fun formatByUnit(formattedNumber: String, threePowerIndex: Int, isMetric: Boolean): String {
val sb = StringBuilder(formattedNumber.length + 4)
sb.append(formattedNumber)
val unitsToUse = "B${if (isMetric) "k" else "K"}MGTPE"
sb.append(unitsToUse[threePowerIndex])
if (threePowerIndex > 0)
if (isMetric) sb.append('B') else sb.append("iB")
return sb.toString()
}
override fun onFormatLong(valueToFormat: Long, unitPowerIndex: Int, isMetric: Boolean): String {
return formatByUnit(String.format("%,d", valueToFormat), unitPowerIndex, isMetric)
}
override fun onFormatDouble(valueToFormat: Double, unitPowerIndex: Int, isMetric: Boolean): String {
//alternative for using numberFormat :
//val formattedNumber = String.format("%,.2f", valueToFormat).let { initialFormattedString ->
// if (initialFormattedString.contains('.'))
// return@let initialFormattedString.dropLastWhile { it == '0' }
// else return@let initialFormattedString
//}
return formatByUnit(numberFormat.format(valueToFormat), unitPowerIndex, isMetric)
}
}
Log.d("AppLog", "formatting of $bytesToFormat bytes (${String.format("%,d", bytesToFormat)})")
Log.d("AppLog", bytesIntoHumanReadable(bytesToFormat, bytesFormatter))
Log.d("AppLog", "Android:${android.text.format.Formatter.formatFileSize(this, bytesToFormat)}")
使用下面的函数来获得确切的信息。它是基于atm_cashwithdraw概念生成的。
getFullMemoryUnit(): Total: [123 MB], Max: [1 GB, 773 MB, 512 KB], Free: [120 MB, 409 KB, 304 Bytes]
public static String getFullMemoryUnit(long unit) {
long BYTE = 1024, KB = BYTE, MB = KB * KB, GB = MB * KB, TB = GB * KB;
long KILO_BYTE, MEGA_BYTE = 0, GIGA_BYTE = 0, TERA_BYTE = 0;
unit = Math.abs(unit);
StringBuffer buffer = new StringBuffer();
if ( unit / TB > 0 ) {
TERA_BYTE = (int) (unit / TB);
buffer.append(TERA_BYTE+" TB");
unit -= TERA_BYTE * TB;
}
if ( unit / GB > 0 ) {
GIGA_BYTE = (int) (unit / GB);
if (TERA_BYTE != 0) buffer.append(", ");
buffer.append(GIGA_BYTE+" GB");
unit %= GB;
}
if ( unit / MB > 0 ) {
MEGA_BYTE = (int) (unit / MB);
if (GIGA_BYTE != 0) buffer.append(", ");
buffer.append(MEGA_BYTE+" MB");
unit %= MB;
}
if ( unit / KB > 0 ) {
KILO_BYTE = (int) (unit / KB);
if (MEGA_BYTE != 0) buffer.append(", ");
buffer.append(KILO_BYTE+" KB");
unit %= KB;
}
if ( unit > 0 ) buffer.append(", "+unit+" Bytes");
return buffer.toString();
}
我刚刚修改了facebookarchive-StringUtils的代码以获得以下格式。与使用apache.hadoop-StringUtils时得到的格式相同
getMemoryUnit(): Total: [123.0 MB], Max: [1.8 GB], Free: [120.4 MB]
public static String getMemoryUnit(long bytes) {
DecimalFormat oneDecimal = new DecimalFormat("0.0");
float BYTE = 1024.0f, KB = BYTE, MB = KB * KB, GB = MB * KB, TB = GB * KB;
long absNumber = Math.abs(bytes);
double result = bytes;
String suffix = " Bytes";
if (absNumber < MB) {
result = bytes / KB;
suffix = " KB";
} else if (absNumber < GB) {
result = bytes / MB;
suffix = " MB";
} else if (absNumber < TB) {
result = bytes / GB;
suffix = " GB";
}
return oneDecimal.format(result) + suffix;
}
以上方法的使用示例:
public static void main(String[] args) {
Runtime runtime = Runtime.getRuntime();
int availableProcessors = runtime.availableProcessors();
long heapSize = Runtime.getRuntime().totalMemory();
long heapMaxSize = Runtime.getRuntime().maxMemory();
long heapFreeSize = Runtime.getRuntime().freeMemory();
System.out.format("Total: [%s], Max: [%s], Free: [%s]\n", heapSize, heapMaxSize, heapFreeSize);
System.out.format("getMemoryUnit(): Total: [%s], Max: [%s], Free: [%s]\n",
getMemoryUnit(heapSize), getMemoryUnit(heapMaxSize), getMemoryUnit(heapFreeSize));
System.out.format("getFullMemoryUnit(): Total: [%s], Max: [%s], Free: [%s]\n",
getFullMemoryUnit(heapSize), getFullMemoryUnit(heapMaxSize), getFullMemoryUnit(heapFreeSize));
}
字节来获取上面的格式
Total: [128974848], Max: [1884815360], Free: [126248240]
为了以人类可读的格式显示时间，请使用函数millisToShortDHMS(长持续时间)。
public static String floatForm (double d)
{
return new DecimalFormat("#.##").format(d);
}
public static String bytesToHuman (long size)
{
long Kb = 1 * 1024;
long Mb = Kb * 1024;
long Gb = Mb * 1024;
long Tb = Gb * 1024;
long Pb = Tb * 1024;
long Eb = Pb * 1024;
if (size < Kb) return floatForm( size ) + " byte";
if (size >= Kb && size < Mb) return floatForm((double)size / Kb) + " Kb";
if (size >= Mb && size < Gb) return floatForm((double)size / Mb) + " Mb";
if (size >= Gb && size < Tb) return floatForm((double)size / Gb) + " Gb";
if (size >= Tb && size < Pb) return floatForm((double)size / Tb) + " Tb";
if (size >= Pb && size < Eb) return floatForm((double)size / Pb) + " Pb";
if (size >= Eb) return floatForm((double)size / Eb) + " Eb";
return "???";
}
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