下面代码，只是实现了计时的效果，倒计时根据下面的代码轻微的改动即可

/**
 * ClassName: TimeCountDownUtils
 * Description TODO 实现年月日时分秒倒计时
 * Created by BAI
 * Data 2017-07-12.
 */

public class TimeCountDownUtils {

    int year = 0;//年
    int month = 0;//月
    int day = 0;//日
    int hour = 0;//时
    int minutes = 0;//分
    int second = 0;//秒

    private Handler mHandler = null;

    /**
     * yyyy-MM-dd HH:mm:ss
     * @param handler
     * @param time
     */
    public TimeCountDownUtils(Handler handler,String time) {
        mHandler = handler;
        String ymd = time.split(" ")[0];
        String hms = time.split(" ")[1];
        year = Integer.parseInt(ymd.split("-")[0]);//年
        month = Integer.parseInt(ymd.split("-")[1]);//月
        day = Integer.parseInt(ymd.split("-")[2]);//日
        hour = Integer.parseInt(hms.split(":")[0]);//时
        minutes = Integer.parseInt(hms.split(":")[1]);//分
        second = Integer.parseInt(hms.split(":")[2]);//秒
        handler.postDelayed(runnable, 1000);
    }
    Runnable runnable = new Runnable() {
        @Override
        public void run() {
            second ++;
            if (second >= 60) {
                second =0;
                minutes+=1;
                if (minutes >= 60) {
                    minutes =0;
                    hour+=1;
                    if (hour >= 24) {
                        hour =0;
                        day+=1;
                    }
                }
            }
            String time = getResultTimeString();
            Message msg = new Message();
            msg.obj = time;
            msg.what = 0x0001;
            mHandler.sendMessage(msg);
            mHandler.postDelayed(this, 1000);
        }
    };

    public String getResultTimeString(){
        String resultTime = "";
        String yea = year+"";
        String mon = getFormatInt(month);
        String da = getFormatInt(day);
        String hou =getFormatInt(hour);
        String minu =getFormatInt(minutes);
        String secon =getFormatInt(second);
        //resultTime = yea+"-"+mon+"-"+da+" "+hou+":"+minu+":"+secon;
        resultTime =hou+":"+minu+":"+secon;
        return  resultTime;
    }

    private String getFormatInt(int time){
        String result = "";
        if(time<10){
            result = "0"+time;
        }else{
            result = ""+time;
        }
        return result;
    }

}