文件大小转换

public class xxx {
    
    public static void main(String[] args) {
        System.out.println(getFileSize1("70753"));
    }

    public static String getFileSize1(String fileSize) {
        String fileSize1 = "";
        if(fileSize==null)
            return fileSize1="0"+"B";
        long fSize = Long.valueOf(fileSize);
        if(fSize<1024){
            fileSize1 = fileSize+"B";//字节
        }else if(fSize>1024){
            BigDecimal bg = new BigDecimal(fSize);
            BigDecimal flsize = new BigDecimal(fSize);
            BigDecimal temp = new BigDecimal(1024);
            if(-1==temp.compareTo(flsize) || 0==temp.compareTo(flsize)){
                //四色五入保留2位小数a.toFixed(2)
                flsize = bg.divide(new BigDecimal(1024), 2,BigDecimal.ROUND_HALF_UP);
                 fileSize1 =flsize+"KB";
            }
            if(-1==temp.compareTo(flsize) || 0==temp.compareTo(flsize)){ //MB
                flsize = flsize.divide(new BigDecimal(1024), 2,BigDecimal.ROUND_HALF_UP);
                fileSize1 = flsize+"M";
            }
        }
        return fileSize1;
    }