JAVA计算文件大小

File f = new File(save_path+File.separator + resouce_id+".zip");

        FileInputStream fis = new FileInputStream(f);

        String resource_size = "";

        DecimalFormat df = new DecimalFormat("#.##");

        double resourcesize = (double)((double)fis.available()/1024);

        if((double)((double)fis.available()/1024)>1000)

        {

            resource_size =df.format((double)((double)fis.available()/1024/1024))+"MB";

        }

        else

        {

            resource_size =df.format((double)((double)fis.available()/1024))+"KB";

        }