1、处理文件大小

public static String getFileSize(String fileSize){
        Double aDouble = Double.valueOf(fileSize);
        if(aDouble>=1024){
            aDouble=aDouble/1024;
            if(aDouble>=1024){
                aDouble=aDouble/1024;
                if(aDouble>=1024){
                    aDouble=aDouble/1024;
                    return getDoubleString(aDouble)+" GB";
                }else{
                    return getDoubleString(aDouble)+" MB";
                }
            }else{
                return getDoubleString(aDouble)+" KB";
            }
        }else{
            return getDoubleString(aDouble)+" Byte";
        }
    }

2.结果处理（小数是0保留整数、有小数保留2位小数）

public static String getDoubleString(double number) {
    String numberStr;
    if (((int) number * 1000) == (int) (number * 1000)) {
        //如果是一个整数
        numberStr = String.valueOf((int) number);
    } else {
        DecimalFormat df = new DecimalFormat("######0.00");
        numberStr = df.format(number);
    }
    return numberStr;
}