将文件大小格式化为 MB、GB 等 [英] Format file size as MB, GB, etc

问题描述

我需要使用合理的单位将文件大小显示为字符串.

例如，

1L ==>1B"；1024L ==>1 KB"；2537253L ==>2.3 MB"

等等

我发现 this previous answer，我觉得不满意.

我想出了自己的解决方案，但也有类似的缺点:

private static final long K = 1024;私有静态最终长 M = K * K；私有静态最终长 G = M * K；私有静态最终长 T = G * K；public static String convertToStringRepresentation(final long value){最终的 long[] 分隔符 = new long[] { T, G, M, K, 1 };final String[] units = new String[] { TB"、GB"、MB"、KB"、B"};如果(值 <1)throw new IllegalArgumentException("无效的文件大小:"+ value);字符串结果 = null;for(int i = 0; i 

主要问题是我对 Decimalformat 和/或 String.format 的了解有限.我希望 1024L、1025L 等映射到 1 KB 而不是 1.0 KB.

所以，有两种可能:

1. 我更喜欢公共图书馆中的开箱即用解决方案，例如 Apache Commons 或 Google Guava.
2. 如果没有，我怎样才能摆脱 '.0' 部分(不求助于字符串替换和正则表达式，我可以自己做)?

解决方案

public static String readableFileSize(long size) {如果(大小 <= 0)返回0"；最终字符串 [] 单位 = 新字符串 [] { "B", "kB", "MB", "GB", "TB" };int digitGroups = (int) (Math.log10(size)/Math.log10(1024));return new DecimalFormat("#,##0.#").format(size/Math.pow(1024, digitGroups)) + " " + units[digitGroups];}

这将工作到 1000 TB....而且程序很短！

I need to display a file size as a string using sensible units.

For example,

1L ==> "1 B";
1024L ==> "1 KB";
2537253L ==> "2.3 MB"

etc.

I found this previous answer, which I didn't find satisfactory.

I have come up with my own solution which has similar shortcomings:

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;

public static String convertToStringRepresentation(final long value){
    final long[] dividers = new long[] { T, G, M, K, 1 };
    final String[] units = new String[] { "TB", "GB", "MB", "KB", "B" };
    if(value < 1)
        throw new IllegalArgumentException("Invalid file size: " + value);
    String result = null;
    for(int i = 0; i < dividers.length; i++){
        final long divider = dividers[i];
        if(value >= divider){
            result = format(value, divider, units[i]);
            break;
        }
    }
    return result;
}

private static String format(final long value,
    final long divider,
    final String unit){
    final double result =
        divider > 1 ? (double) value / (double) divider : (double) value;
    return String.format("%.1f %s", Double.valueOf(result), unit);
}

The main problem is my limited knowledge of Decimalformat and / or String.format. I would like 1024L, 1025L, etc. to map to 1 KB rather than 1.0 KB.

So, two possibilities:

1. I would prefer a good out-of-the-box solution in a public library like Apache Commons or Google Guava.
2. If there isn't, how can I get rid of the '.0' part (without resorting to string replacement and regex, I can do that myself)?

解决方案

public static String readableFileSize(long size) {
    if(size <= 0) return "0";
    final String[] units = new String[] { "B", "kB", "MB", "GB", "TB" };
    int digitGroups = (int) (Math.log10(size)/Math.log10(1024));
    return new DecimalFormat("#,##0.#").format(size/Math.pow(1024, digitGroups)) + " " + units[digitGroups];
}

This will work up to 1000 TB.... and the program is short!

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