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
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)。
其他回答
下面是一个快速，简单和可读的代码片段来实现这一点:
/**
* Converts byte size to human readable strings (also declares useful constants)
*
* @see <a href="https://en.wikipedia.org/wiki/File_size">File size</a>
*/
@SuppressWarnings("SpellCheckingInspection")
public class HumanReadableSize {
public static final double
KILO = 1000L, // 1000 power 1 (10 power 3)
KIBI = 1024L, // 1024 power 1 (2 power 10)
MEGA = KILO * KILO, // 1000 power 2 (10 power 6)
MEBI = KIBI * KIBI, // 1024 power 2 (2 power 20)
GIGA = MEGA * KILO, // 1000 power 3 (10 power 9)
GIBI = MEBI * KIBI, // 1024 power 3 (2 power 30)
TERA = GIGA * KILO, // 1000 power 4 (10 power 12)
TEBI = GIBI * KIBI, // 1024 power 4 (2 power 40)
PETA = TERA * KILO, // 1000 power 5 (10 power 15)
PEBI = TEBI * KIBI, // 1024 power 5 (2 power 50)
EXA = PETA * KILO, // 1000 power 6 (10 power 18)
EXBI = PEBI * KIBI; // 1024 power 6 (2 power 60)
private static final DecimalFormat df = new DecimalFormat("#.##");
public static String binaryBased(long size) {
if (size < 0) {
throw new IllegalArgumentException("Argument cannot be negative");
} else if (size < KIBI) {
return df.format(size).concat("B");
} else if (size < MEBI) {
return df.format(size / KIBI).concat("KiB");
} else if (size < GIBI) {
return df.format(size / MEBI).concat("MiB");
} else if (size < TEBI) {
return df.format(size / GIBI).concat("GiB");
} else if (size < PEBI) {
return df.format(size / TEBI).concat("TiB");
} else if (size < EXBI) {
return df.format(size / PEBI).concat("PiB");
} else {
return df.format(size / EXBI).concat("EiB");
}
}
public static String decimalBased(long size) {
if (size < 0) {
throw new IllegalArgumentException("Argument cannot be negative");
} else if (size < KILO) {
return df.format(size).concat("B");
} else if (size < MEGA) {
return df.format(size / KILO).concat("KB");
} else if (size < GIGA) {
return df.format(size / MEGA).concat("MB");
} else if (size < TERA) {
return df.format(size / GIGA).concat("GB");
} else if (size < PETA) {
return df.format(size / TERA).concat("TB");
} else if (size < EXA) {
return df.format(size / PETA).concat("PB");
} else {
return df.format(size / EXA).concat("EB");
}
}
}
注意:
上面的代码冗长而简单。 它不使用循环(循环应该只在您不知道在编译期间需要迭代多少次时使用) 它不会进行不必要的库调用(StringBuilder, Math等) 上面的代码是快速的，使用非常少的内存。基于在我个人的入门级云计算机上运行的基准测试，它是最快的(在这些情况下性能并不重要，但仍然如此) 以上代码是一个很好的答案的修改版本
这是另一个简洁的解决方案，没有循环，但具有区域敏感格式和正确的二进制前缀:
import java.util.Locale;
public final class Bytes {
private Bytes() {
}
public static String format(long value, Locale locale) {
if (value < 1024) {
return value + " B";
}
int z = (63 - Long.numberOfLeadingZeros(value)) / 10;
return String.format(locale, "%.1f %siB", (double) value / (1L << (z * 10)), " KMGTPE".charAt(z));
}
}
测试:
Locale locale = Locale.getDefault()
System.out.println(Bytes.format(1L, locale))
System.out.println(Bytes.format(2L * 1024, locale))
System.out.println(Bytes.format(3L * 1024 * 1024, locale))
System.out.println(Bytes.format(4L * 1024 * 1024 * 1024, locale))
System.out.println(Bytes.format(5L * 1024 * 1024 * 1024 * 1024, locale))
System.out.println(Bytes.format(6L * 1024 * 1024 * 1024 * 1024 * 1024, locale))
System.out.println(Bytes.format(Long.MAX_VALUE, locale))
输出:
1 B
2.0 KiB
3.0 MiB
4.0 GiB
5.0 GiB
6.0 PiB
8.0 EiB
Kotlin版本通过扩展属性
如果您正在使用Kotlin，那么通过这些扩展名属性格式化文件大小非常容易。它是无循环的，完全基于纯数学。
HumanizeUtils.kt
import java.io.File
import kotlin.math.log2
import kotlin.math.pow
/**
* @author aminography
*/
val File.formatSize: String
get() = length().formatAsFileSize
val Int.formatAsFileSize: String
get() = toLong().formatAsFileSize
val Long.formatAsFileSize: String
get() = log2(if (this != 0L) toDouble() else 1.0).toInt().div(10).let {
val precision = when (it) {
0 -> 0; 1 -> 1; else -> 2
}
val prefix = arrayOf("", "K", "M", "G", "T", "P", "E", "Z", "Y")
String.format("%.${precision}f ${prefix[it]}B", toDouble() / 2.0.pow(it * 10.0))
}
用法:
println("0: " + 0.formatAsFileSize)
println("170: " + 170.formatAsFileSize)
println("14356: " + 14356.formatAsFileSize)
println("968542985: " + 968542985.formatAsFileSize)
println("8729842496: " + 8729842496.formatAsFileSize)
println("file: " + file.formatSize)
结果:
0: 0 B
170: 170 B
14356: 14.0 KB
968542985: 923.67 MB
8729842496: 8.13 GB
file: 6.15 MB
这是一个Go版本。为了简单起见，我只包含了二进制输出情况。
func sizeOf(bytes int64) string {
const unit = 1024
if bytes < unit {
return fmt.Sprintf("%d B", bytes)
}
fb := float64(bytes)
exp := int(math.Log(fb) / math.Log(unit))
pre := "KMGTPE"[exp-1]
div := math.Pow(unit, float64(exp))
return fmt.Sprintf("%.1f %ciB", fb / div, pre)
}
创建接口:
public interface IUnits {
public String format(long size, String pattern);
public long getUnitSize();
}
创建StorageUnits类:
import java.text.DecimalFormat;
public class StorageUnits {
private static final long K = 1024;
private static final long M = K * K;
private static final long G = M * K;
private static final long T = G * K;
enum Unit implements IUnits {
TERA_BYTE {
@Override
public String format(long size, String pattern) {
return format(size, getUnitSize(), "TB", pattern);
}
@Override
public long getUnitSize() {
return T;
}
@Override
public String toString() {
return "Terabytes";
}
},
GIGA_BYTE {
@Override
public String format(long size, String pattern) {
return format(size, getUnitSize(), "GB", pattern);
}
@Override
public long getUnitSize() {
return G;
}
@Override
public String toString() {
return "Gigabytes";
}
},
MEGA_BYTE {
@Override
public String format(long size, String pattern) {
return format(size, getUnitSize(), "MB", pattern);
}
@Override
public long getUnitSize() {
return M;
}
@Override
public String toString() {
return "Megabytes";
}
},
KILO_BYTE {
@Override
public String format(long size, String pattern) {
return format(size, getUnitSize(), "kB", pattern);
}
@Override
public long getUnitSize() {
return K;
}
@Override
public String toString() {
return "Kilobytes";
}
};
String format(long size, long base, String unit, String pattern) {
return new DecimalFormat(pattern).format(
Long.valueOf(size).doubleValue() /
Long.valueOf(base).doubleValue()
) + unit;
}
}
public static String format(long size, String pattern) {
for(Unit unit : Unit.values()) {
if(size >= unit.getUnitSize()) {
return unit.format(size, pattern);
}
}
return ("???(" + size + ")???");
}
public static String format(long size) {
return format(size, "#,##0.#");
}
}
叫它:
class Main {
public static void main(String... args) {
System.out.println(StorageUnits.format(21885));
System.out.println(StorageUnits.format(2188121545L));
}
}
输出:
21.4kB
2GB
推荐文章
- 在流中使用Java 8 foreach循环移动到下一项
- 访问限制:'Application'类型不是API(必需库rt.jar的限制)
- 用Java计算两个日期之间的天数
- 如何配置slf4j-simple
- 在Jar文件中运行类
- 带参数的可运行?
- 我如何得到一个字符串的前n个字符而不检查大小或出界?
- 我可以在Java中设置enum起始值吗?
- Java中的回调函数
- c#和Java中的泛型有什么不同?和模板在c++ ?
- 在Java中，流相对于循环的优势是什么?
- Jersey在未找到InjectionManagerFactory时停止工作
- 在Java流是peek真的只是调试?
- Recyclerview不调用onCreateViewHolder
- 将JSON字符串转换为HashMap
