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);
}

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):

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

我通常是这样做的:

public static String getFileSize(double size) {
    return _getFileSize(size,0,1024);
}

public static String _getFileSize(double size, int i, double base) {
    String units = " KMGTP";
    String unit = (i>0)?(""+units.charAt(i)).toUpperCase()+"i":"";
    if(size<base)
        return size +" "+unit.trim()+"B";
    else {
        size = Math.floor(size/base);
        return _getFileSize(size,++i,base);
    }
}

public String humanReadable(long size) {
    long limit = 10 * 1024;
    long limit2 = limit * 2 - 1;
    String negative = "";
    if(size < 0) {
        negative = "-";
        size = Math.abs(size);
    }

    if(size < limit) {
        return String.format("%s%s bytes", negative, size);
    } else {
        size = Math.round((double) size / 1024);
        if (size < limit2) {
            return String.format("%s%s kB", negative, size);
        } else {
            size = Math.round((double)size / 1024);
            if (size < limit2) {
                return String.format("%s%s MB", negative, size);
            } else {
                size = Math.round((double)size / 1024);
                if (size < limit2) {
                    return String.format("%s%s GB", negative, size);
                } else {
                    size = Math.round((double)size / 1024);
                        return String.format("%s%s TB", negative, size);
                }
            }
        }
    }
}

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";
    }
}