自己实现一个简单的列表倒计时

对于倒计时，为了让时间更精细化，以及列表Item的复用性考虑，个人觉得最好的处理办法是接口返回两个时间，一个倒计时结束时间、一个服务器时间，然后我们本地需要算服务器时间与本地时间的差值，第一次算出来后存下来，然后 倒计时时间 = 倒计时结束时间 -（本地时间+时间差值），然后为了复用，我们可以在RecyclerView的onViewAttachedToWindow重新开启倒计时，在onViewDetachedFromWindow的时候关闭当前item的倒计时。

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最近项目需要的样式是这样的，没找到现成的库，所以自己就搞了一个简单的，下面是源码：
public class CountDownView extends LinearLayout {

private TextView tvDay, tvHours, tvMinutes, tvSeconds;
private TextView tvDaySuffix, tvHoursSuffix, tvMinutesSuffix;
private CustomCountDownTimer mCustomCountDownTimer;
private long countDownTime;

public CountDownView(Context context) {
    this(context, null);
}

public CountDownView(Context context, @Nullable AttributeSet attrs) {
    this(context, attrs, 0);
}

public CountDownView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);

    initView();
}

private void initView() {
    View view = LayoutInflater.from(getContext()).inflate(R.layout.count_down_view, this);

    tvDay = view.findViewById(R.id.tv_day);
    tvDaySuffix = view.findViewById(R.id.tv_day_suffix);

    tvHours = view.findViewById(R.id.tv_hour);
    tvHoursSuffix = view.findViewById(R.id.tv_hour_suffix);

    tvMinutes = view.findViewById(R.id.tv_minutes);
    tvMinutesSuffix = view.findViewById(R.id.tv_minutes_suffix);

    tvSeconds = view.findViewById(R.id.tv_seconds);
}

public void setItemBackGround(int resId){
    tvDay.setBackground(getResources().getDrawable(resId));
    tvHours.setBackground(getResources().getDrawable(resId));
    tvMinutes.setBackground(getResources().getDrawable(resId));
    tvSeconds.setBackground(getResources().getDrawable(resId));
}

public void setSuffixColor(String color){
    tvDaySuffix.setTextColor(Color.parseColor(color));
    tvHoursSuffix.setTextColor(Color.parseColor(color));
    tvMinutesSuffix.setTextColor(Color.parseColor(color));
}

public void setEndTime(long ms) {
    countDownTime = ms;
    int day;
    int hour;

    day = (int) (ms / (1000 * 60 * 60 * 24));
    hour = (int) ((ms % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));

    int minute = (int) ((ms % (1000 * 60 * 60)) / (1000 * 60));
    int second = (int) ((ms % (1000 * 60)) / 1000);

    if (day > 0) {
        tvDay.setVisibility(VISIBLE);
        tvDaySuffix.setVisibility(VISIBLE);
        tvDay.setText(day + "天");
    } else {
        tvDay.setVisibility(GONE);
        tvDaySuffix.setVisibility(GONE);
    }

    if (hour > 0) {
        tvHours.setText(hour < 10 ? "0" + hour : "" + hour);
    } else {
        tvHours.setText("00");
    }
    if (minute > 0){
        tvMinutes.setText(minute < 10 ? "0" + minute : "" + minute);
    }else {
        tvMinutes.setText("00");
    }
    if (second > 0){
        tvSeconds.setText(second == 0 ? "00" : (second < 10 ? "0" + second : "" + second));
    }else {
        tvSeconds.setText("00");
    }
}

public void start() {
    if (countDownTime <= 0) return;
    if (null != mCustomCountDownTimer) {
        mCustomCountDownTimer.stop();
        mCustomCountDownTimer = null;
    }
    mCustomCountDownTimer = new CustomCountDownTimer(countDownTime, 1000) {
        @Override
        public void onTick(long millisUntilFinished) {
            setEndTime(millisUntilFinished);
        }

        @Override
        public void onFinish() {
            // callback
            if (null != listener) {
                listener.onEnd();
            }
        }
    };
    mCustomCountDownTimer.start();
}

public void stop() {
    if (null != mCustomCountDownTimer) mCustomCountDownTimer.stop();
}

public OnCountDownEndListener listener;

public void setOnCountDownEndListener(OnCountDownEndListener listener) {
    this.listener = listener;
}

public interface OnCountDownEndListener {
    void onEnd();
}

}

public abstract class CustomCountDownTimer {

private static final int MSG = 1;
private final long mMillisInFuture;
private final long mCountdownInterval;
private long mStopTimeInFuture;
private long mPauseTimeInFuture;
private boolean isStop = false;
private boolean isPause = false;

/**
 * @param millisInFuture    总倒计时时间
 * @param countDownInterval 倒计时间隔时间
 */
public CustomCountDownTimer(long millisInFuture, long countDownInterval) {
    // 解决秒数有时会一开始就减去了2秒问题（如10秒总数的，刚开始就8999，然后没有不会显示9秒，直接到8秒）
    if (countDownInterval > 1000) millisInFuture += 15;
    mMillisInFuture = millisInFuture;
    mCountdownInterval = countDownInterval;
}

private synchronized CustomCountDownTimer start(long millisInFuture) {
    isStop = false;
    if (millisInFuture <= 0) {
        onFinish();
        return this;
    }
    mStopTimeInFuture = SystemClock.elapsedRealtime() + millisInFuture;
    mHandler.sendMessage(mHandler.obtainMessage(MSG));
    return this;
}

/**
 * 开始倒计时
 */
public synchronized final void start() {
    start(mMillisInFuture);
}

/**
 * 停止倒计时
 */
public synchronized final void stop() {
    isStop = true;
    mHandler.removeMessages(MSG);
}

/**
 * 暂时倒计时
 * 调用{@link #restart()}方法重新开始
 */
public synchronized final void pause() {
    if (isStop) return ;

    isPause = true;
    mPauseTimeInFuture = mStopTimeInFuture - SystemClock.elapsedRealtime();
    mHandler.removeMessages(MSG);
}

/**
 * 重新开始
 */
public synchronized final void restart() {
    if (isStop || !isPause) return ;

    isPause = false;
    start(mPauseTimeInFuture);
}

/**
 * 倒计时间隔回调
 * @param millisUntilFinished 剩余毫秒数
 */
public abstract void onTick(long millisUntilFinished);

/**
 * 倒计时结束回调
 */
public abstract void onFinish();

private Handler mHandler = new Handler() {

    @Override
    public void handleMessage(Message msg) {

        synchronized (CustomCountDownTimer.this) {
            if (isStop || isPause) {
                return;
            }

            final long millisLeft = mStopTimeInFuture - SystemClock.elapsedRealtime();
            if (millisLeft <= 0) {
                onFinish();
            } else {
                long lastTickStart = SystemClock.elapsedRealtime();
                onTick(millisLeft);

                // take into account user's onTick taking time to execute
                long delay = lastTickStart + mCountdownInterval - SystemClock.elapsedRealtime();

                // special case: user's onTick took more than interval to
                // complete, skip to next interval
                while (delay < 0) delay += mCountdownInterval;

                sendMessageDelayed(obtainMessage(MSG), delay);
            }
        }
    }
};

}

adapter中代码如下：
public class WelfareProductsListAdapter extends BaseQuickAdapter {

//服务器与手机本地时间差
public long gapTime;

public WelfareProductsListAdapter(int layoutResId, @Nullable List data) {
    super(layoutResId, data);
}

@Override
protected void convert(@NonNull BaseViewHolder helper, WelfareItemModel item) {
 
    CountDownView countdownView = helper.getView(R.id.cv_countdownView_turn);
    countdownView.setTag(item.getId());

    long localTime = System.currentTimeMillis() / 1000;
    //倒计时的时间
    long endTime = (item.getStartTime() - (localTime + gapTime)) * 1000;
    if (endTime > 0) {
        countdownView.setEndTime(endTime);
        countdownView.start();
    } else {
        countdownView.stop();
    }
    countdownView.setOnCountDownEndListener(() -> {
        notifyItemChanged(helper.getAdapterPosition());
    });
}

@Override
public void onViewAttachedToWindow(BaseViewHolder holder) {
    super.onViewAttachedToWindow(holder);
    CountDownView countdownView = holder.getView(R.id.cv_countdownView_turn);
    int position = holder.getAdapterPosition();
    if (countdownView != null) {
        long localTime = System.currentTimeMillis() / 1000;
        //倒计时的时间
        long endTime = (getItem(position).getStartTime() - (localTime + gapTime)) * 1000;
        if (endTime > 0) {
            countdownView.setEndTime(endTime);
            countdownView.start();
            countdownView.setVisibility(View.VISIBLE);
        } else {
            countdownView.stop();
            countdownView.setVisibility(View.INVISIBLE);
        }
    }
}

@Override
public void onViewDetachedFromWindow(@NonNull BaseViewHolder holder) {
    super.onViewDetachedFromWindow(holder);
    CountDownView countdownView = holder.getView(R.id.cv_countdownView_turn);
    if (countdownView != null) {
        countdownView.stop();
    }
}

}