/**
     * 显示分钟和秒的
     * @param sec
     * @return
     */
    public static String timeToFormatStrMinAndSec(long sec){
        String str = "";
        long min,second;
        min = sec/60;
        second = sec%60;

        if(min == 0){
            str = str+"00:";
        }else if(min<10){
            str = str+"0"+min+":" ;
        }else{
            str = str+min+":" ;
        }
        if(second<10){
            str = str+"0"+second;
        }else{
            str = str+second;
        }
        return str;
    }