在Android的开发中，我们经常遇见倒计时的操作，通常使用Timer和Handler共同操作来完成。当然也可以使用Android系统控件CountDownTimer，这里我们封装成一个控件，也方便大家的使用。

首先上一张效果图吧：

说一下造成卡顿的原因，由于滑动的时候，adapter的getView频繁的创建和销毁，就会出现卡顿和数据错位问题，那么我们每一个item的倒计时就需要单独维护，这里我用的Handler与timer及TimerTask结合的方法，我们知道TimerTask运行在自己子线程，然后通过Timer的schedule（）方法实现倒计时功能，最后通过Hander实现View的刷新，其核心代码如下：

public class CountDownView extends LinearLayout {
 
 @BindView(R.id.tv_day)
 TextView tvDay;
 @BindView(R.id.tv_hour)
 TextView tvHour;
 @BindView(R.id.tv_minute)
 TextView tvMinute;
 @BindView(R.id.tv_second)
 TextView tvSecond;
 
 @BindView(R.id.day)
 TextView day;
 @BindView(R.id.hour)
 TextView hour;
 @BindView(R.id.minute)
 TextView minute;
 
 private Context context;
 
 private int viewBg;//倒计时的背景
 private int cellBg;//每个倒计时的背景
 private int cellTextColor;//文字颜色
 private int textColor;//外部：等颜色
 private int textSize = 14;//外部文字大小
 private int cellTextSize = 12;//cell文字大小
 
 private TimerTask timerTask = null;
 private Timer timer = new Timer();
 private Handler handler = new Handler() {
 
 public void handleMessage(Message msg) {
  countDown();
 }
 };
 
 public CountDownView(Context context, AttributeSet attrs) {
 this(context, attrs, 0);
 this.context = context;
 }
 
 public CountDownView(Context context, AttributeSet attrs, int defStyleAttr) {
 super(context, attrs, defStyleAttr);
 this.context = context;
 initAttrs(attrs, defStyleAttr);
 initView(context);
 }
 
 private void initAttrs(AttributeSet attrs, int defStyle) {
 TypedArray typedArray = getContext().obtainStyledAttributes(attrs, R.styleable.CountDownView, defStyle,0);
 viewBg = typedArray.getColor(R.styleable.CountDownView_viewBg, Color.parseColor("#FFFFFF"));
 cellBg = typedArray.getColor(R.styleable.CountDownView_cellBg, Color.parseColor("#F4F4F4"));
 cellTextColor = typedArray.getColor(R.styleable.CountDownView_cellTextColor, Color.parseColor("#646464"));
 textColor = typedArray.getColor(R.styleable.CountDownView_TextColor, Color.parseColor("#B3B3B3"));
 textSize = (int) typedArray.getDimension(R.styleable.CountDownView_TextSize, UIUtils.dp2px(getContext(), 14));
 cellTextSize = (int) typedArray.getDimension(R.styleable.CountDownView_cellTextSize, UIUtils.dp2px(getContext(), 12));
 typedArray.recycle();
 
 }
 
 private void initView(Context context) {
 LayoutInflater inflater = (LayoutInflater) context
  .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
 View view = inflater.inflate(R.layout.layout_countdown_layout, this);
 ButterKnife.bind(view);
 
 initProperty();
 }
 
 private void initProperty() {
 tvDay.setBackgroundColor(cellBg);
 tvHour.setBackgroundColor(cellBg);
 tvMinute.setBackgroundColor(cellBg);
 tvSecond.setBackgroundColor(cellBg);
 
 tvDay.setTextColor(cellTextColor);
 tvHour.setTextColor(cellTextColor);
 tvMinute.setTextColor(cellTextColor);
 tvSecond.setTextColor(cellTextColor);
 
 day.setTextColor(textColor);
 hour.setTextColor(textColor);
 minute.setTextColor(textColor);
 }
 
 
 public void setLeftTime(long leftTime) {
 if (leftTime <= 0) return;
 long time = leftTime / 1000;
 long day = time / (3600 * 24);
 long hours = (time - day * 3600 * 24) / 3600;
 long minutes = (time - day * 3600 * 24 - hours * 3600) / 60;
 long seconds = time - day * 3600 * 24 - hours * 3600 - minutes * 60;
 
 setTextTime(time);
 }
 
 
 public void start() {
 if (timerTask == null) {
  timerTask = new TimerTask() {
  @Override
  public void run() {
   handler.sendEmptyMessage(0);
  }
 
  };
  timer.schedule(timerTask, 1000, 1000);
//  timer.schedule(new TimerTask() {
//  @Override
//  public void run() {
//   handler.sendEmptyMessage(0);
//  }
//  }, 0, 1000);
 }
 }
 
 public void stop() {
 if (timer != null) {
  timer.cancel();
  timer = null;
 }
 }
 
 //保证天，时，分，秒都两位显示，不足的补0
 private void setTextTime(long time) {
 String[] s = TimeUtils.formatTimer(time);
 tvDay.setText(s[0]);
 tvHour.setText(s[1]);
 tvMinute.setText(s[2]);
 tvSecond.setText(s[3]);
 }
 
 private void countDown() {
 if (isCarry4Unit(tvSecond)) {
  if (isCarry4Unit(tvMinute)) {
  if (isCarry4Unit(tvHour)) {
   if (isCarry4Unit(tvDay)) {
   stop();
   }
  }
  }
 }
 }
 
 private boolean isCarry4Unit(TextView tv) {
 int time = Integer.valueOf(tv.getText().toString());
 time = time - 1;
 if (time < 0) {
  time = 59;
  tv.setText(time + "");
  return true;
 } else if (time < 10) {
  tv.setText("0" + time);
  return false;
 } else {
  tv.setText(time + "");
  return false;
 }
 }
}

另一种写法：

public class CountDownTimerView extends LinearLayout {
 
 private TextView hourView, minuteView, secondView;
 private LimitTimer mTimer;
 private Handler handler;
 public static final int START_LIMIT_TIME_MSG = 0x0111;
 public static final int END_LIMIT_TIME_MSG = 0x0112;
 private long endTime, leftTime;
 private LimitTimeListener listener=null;
 
 public CountDownTimerView(Context context) {
 super(context);
 initView(context);
 }
 
 public CountDownTimerView(Context context, AttributeSet attrs) {
 super(context, attrs);
 initView(context);
 }
 
 private void initView(Context context) {
 setOrientation(HORIZONTAL);
 setGravity(Gravity.CENTER_VERTICAL);
 inflate(context, R.layout.layout_countdown_layout, this);
 hourView = (TextView) findViewById(R.id.tv_hour);
 minuteView = (TextView) findViewById(R.id.tv_minute);
 secondView = (TextView) findViewById(R.id.tv_second);
 }
 
 public long getLeftTime() {
 return leftTime;
 }
 
 //设置剩余时间
 public void initLeftTime(long endTime) {
 endTime=endTime*1000;
 if (null != mTimer) {
  mTimer.cancel();
  mTimer = null;
 }
 this.endTime = endTime;
 mTimer = new LimitTimer(endTime, 1000);
 mTimer.start();
 if (handler != null) {
  handler.sendEmptyMessage(START_LIMIT_TIME_MSG);
 }
 }
 
 /**
 * 如果该控件使用在碎片中，返回时，则最好还是要stop
 */
 public void stopTimeCount() {
 if (null != mTimer) {
  mTimer.cancel();
  mTimer = null;
 }
 }
 
 public Handler getHandler() {
 return handler;
 }
 
 public void setHandler(Handler handler) {
 this.handler = handler;
 }
 
 private class LimitTimer extends CountDownTimer {
 
 public LimitTimer(long millisInFuture, long countDownInterval) {
  super(0 != leftTime ? leftTime : endTime, countDownInterval);
 }
 
 @Override
 public void onTick(long millisUntilFinished) {
  leftTime = millisUntilFinished;
  long totalSecond = millisUntilFinished / 1000;
  int second = (int) (totalSecond % 60);
  int minute = (int) ((totalSecond / 60) % 60);
  int hour = (int) ((totalSecond / 3600) % 24);
  int day = (int) (totalSecond / (3600 * 24));
 
  formatView(hourView, hour);
  formatView(minuteView, minute);
  formatView(secondView, second);
 }
 
 @Override
 public void onFinish() {
  String zero = "00";
  hourView.setText(zero);
  minuteView.setText(zero);
  secondView.setText(zero);
  if (null != handler) {
  handler.sendEmptyMessage(END_LIMIT_TIME_MSG);
  }
  if (listener!=null){
  listener.onTimeOver(true);
  }
 }
 
 private void formatView(TextView view, int time) {
  DecimalFormat df = new DecimalFormat("#00");
  view.setText(df.format(time));
 }
 }
 
 //倒计时结束监听
 public void setOnLimitTimeListener(LimitTimeListener listener) {
 this.listener = listener;
 }
 public interface LimitTimeListener {
 void onTimeOver(boolean flag);
 }
 
 @Override
 protected void onDetachedFromWindow() {
 super.onDetachedFromWindow();
 if (handler != null) {
  handler.removeMessages(START_LIMIT_TIME_MSG);
 }
 }
}

涉及到的布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:orientation="horizontal">
 
 
 <TextView
 android:id="@+id/tv_hour"
 style="@style/style_countdown" />
 
 <TextView
 style="@style/style_wrap_content"
 android:layout_marginLeft="3dp"
 android:layout_marginRight="3dp"
 android:layout_gravity="center_vertical"
 android:text="时"
 android:textColor="@color/color_646464" />
 
 <TextView
 android:id="@+id/tv_minute"
 style="@style/style_countdown" />
 
 <TextView
 style="@style/style_wrap_content"
 android:layout_marginLeft="3dp"
 android:layout_marginRight="3dp"
 android:layout_gravity="center_vertical"
 android:text="分"
 android:textColor="@color/color_646464" />
 
 <TextView
 android:id="@+id/tv_second"
 style="@style/style_countdown" />
 
 <TextView
 style="@style/style_wrap_content"
 android:layout_marginLeft="3dp"
 android:layout_marginRight="3dp"
 android:layout_gravity="center_vertical"
 android:text="秒"
 android:textColor="@color/color_646464" />
</LinearLayout>

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