我使用了一个比公认答案稍作修改的方法:

public static String formatFileSize(long bytes) {
    if (bytes <= 0)
        return "";
    if (bytes < 1000)
        return bytes + " B";

    CharacterIterator ci = new StringCharacterIterator("kMGTPE");
    while (bytes >= 99_999) {
        bytes /= 1000;
        ci.next();
    }
    return String.format(Locale.getDefault(), "%.1f %cB", bytes / 1000.0, ci.current());
}

因为我想看到另一个输出:

                              SI

                   0:            <--------- instead of 0 B
                  27:       27 B
                 999:      999 B
                1000:     1.0 kB
                1023:     1.0 kB
                1024:     1.0 kB
                1728:     1.7 kB
              110592:     0.1 MB <--------- instead of 110.6 kB
             7077888:     7.1 MB
           452984832:     0.5 GB <--------- instead of 453.0 MB
         28991029248:    29.0 GB

String[] fileSizeUnits = {"bytes", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"};

public String calculateProperFileSize(double bytes){
    String sizeToReturn = "";
    int index = 0;
    for(index = 0; index < fileSizeUnits.length; index++){
        if(bytes < 1024){
            break;
        }
        bytes = bytes / 1024;
    }

    System.out.println("File size in proper format: " + bytes + " " + fileSizeUnits[index]);
    sizeToReturn = String.valueOf(bytes) + " " + fileSizeUnits[index];
    return sizeToReturn;
}

只需添加更多的文件单元(如果有任何缺失)，你将看到单元大小达到该单元(如果你的文件有那么长):

private String bytesIntoHumanReadable(long bytes) {
    long kilobyte = 1024;
    long megabyte = kilobyte * 1024;
    long gigabyte = megabyte * 1024;
    long terabyte = gigabyte * 1024;

    if ((bytes >= 0) && (bytes < kilobyte)) {
        return bytes + " B";

    } else if ((bytes >= kilobyte) && (bytes < megabyte)) {
        return (bytes / kilobyte) + " KB";

    } else if ((bytes >= megabyte) && (bytes < gigabyte)) {
        return (bytes / megabyte) + " MB";

    } else if ((bytes >= gigabyte) && (bytes < terabyte)) {
        return (bytes / gigabyte) + " GB";

    } else if (bytes >= terabyte) {
        return (bytes / terabyte) + " TB";

    } else {
        return bytes + " Bytes";
    }
}

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

private static final String[] Q = new String[]{"", "K", "M", "G", "T", "P", "E"};

public String getAsString(long bytes)
{
    for (int i = 6; i > 0; i--)
    {
        double step = Math.pow(1024, i);
        if (bytes > step) return String.format("%3.1f %s", bytes / step, Q[i]);
    }
    return Long.toString(bytes);
}

你可以使用StringUtils的TraditionalBinarPrefix:

public static String humanReadableInt(long number) {
    return TraditionalBinaryPrefix.long2String(number, ””, 1);
}