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目录
利用系统API的几种实现方式
使用 CountDownTimer 实现 - 最简洁【推荐】
CountDownTimer 简介
使用案例
使用 RxJava 实现 - 方便强大【推荐】
使用 Timer + Handler 实现 - 麻烦【不推荐】
Timer + 普通 Handler - 麻烦
Timer + 静态 Handler - 更麻烦
Timer + runOnUiThread - 也麻烦
使用纯 Handler 实现 - 特麻烦【强烈不建议】
开源框架 CountdownView 简介
在 RecyclerView 中实现倒计时
更改数据源方式 - 简单但不可靠
让 System 帮我们倒计时 - 推荐
自己维护倒计时 - 既麻烦又低效

@BindView(R.id.send) Button send;//发送验证码
new CountDownTimer(60000, 1000) {@Overridepublic void onTick(long millisUntilFinished) {send.setText(millisUntilFinished / 1000 + "S");}@Overridepublic void onFinish() {send.setEnabled(true);send.setText("重新发送");}
}.start();

CountDownTimer(long millisInFuture, long countDownInterval)

final void cancel()
final CountDownTimer start()

abstract void onFinish()：Callback fired when the time is up.
abstract void onTick(long millisUntilFinished)：Callback fired on regular interval. millisUntilFinished: The amount of time until finished.

@BindView(R.id.send) Button send;//发送验证码
private CountDownTimer timer;//使用CountDownTimer
​
@OnClick({R.id.send, R.id.next})
public void onClickIv(View v) {switch (v.getId()) {case R.id.send:setTimer();//实际是要在点击之后判断如果符合倒计时条件才调用 setTimer 方法，要在失败后调用 destoryTimerbreak;}
}
​
@Override
protected void onDestroy() {super.onDestroy();destoryTimer();
}
​
private void setTimer() {send.setEnabled(false);timer = new CountDownTimer(60 * 1000, 1000) {@Overridepublic void onTick(long millisUntilFinished) {int time = (int) (millisUntilFinished / 1000);send.setText(time + "s");}@Overridepublic void onFinish() {destoryTimer();}};timer.start();
}
​
private void destoryTimer() {send.setEnabled(true);send.setText("获取验证码");if (timer != null) {timer.cancel();timer = null;}
}

@BindView(R.id.send) Button send;//发送验证码
private Disposable disposable;@OnClick({R.id.send, R.id.next})
public void onClickIv(View v) {switch (v.getId()) {case R.id.send:startCountDown();break;}
}
​
@Override
protected void onDestroy() {super.onDestroy();if (disposable != null && !disposable.isDisposed()) {disposable.dispose();}
}
​
private void startCountDown() {send.setEnabled(false);disposable = Observable.intervalRange(0, 10, 0, 1, TimeUnit.SECONDS) //起始值，发送总数量，初始延迟，固定延迟.observeOn(Schedulers.io()).subscribeOn(AndroidSchedulers.mainThread()).subscribe(time -> send.setText((30 - time) + "s"),Throwable::printStackTrace,() -> runOnUiThread(() -> {send.setEnabled(true);send.setText("获取验证码");}));
}

@BindView(R.id.send) Button send;//发送验证码
private int time = 60;//倒计时时间
private Timer timer;
​
@OnClick({R.id.send, R.id.next})
public void onClickIv(View v) {switch (v.getId()) {case R.id.send:setTimer();//实际是要在点击之后判断如果符合倒计时条件才调用 setTimer 方法，要在失败后调用 destoryTimerbreak;}
}
​
@Override
protected void onDestroy() {super.onDestroy();destoryTimer();
}
​
@SuppressLint("HandlerLeak")
private Handler handler = new Handler() {@Overridepublic void handleMessage(android.os.Message msg) {switch (msg.what) {case 1:send.setText(time + "s");break;case 2:destoryTimer();break;}}
};
​
//定时器
private void setTimer() {send.setEnabled(false);//不可点击timer = new Timer();TimerTask task = new TimerTask() {@Overridepublic void run() {time--;if (time > 0) {handler.sendEmptyMessage(1);} else {handler.sendEmptyMessage(2);}}};timer.schedule(task, 0, 1000);//每隔一秒钟执行一次
}
​
private void destoryTimer() {time = 60;//重新倒计时send.setEnabled(true);//重新可点击send.setText("重新发送");//重设文字if (timer != null) {timer.cancel();timer = null;}if (handler!=null) {handler.removeCallbacksAndMessages(null);}
}

@BindView(R.id.send) Button send;//发送验证码
private int time = 60;//倒计时时间
private Timer timer;
​
@OnClick({R.id.send, R.id.next})
public void onClickIv(View v) {switch (v.getId()) {case R.id.send:setTimer();//实际是要在点击之后判断如果符合倒计时条件才调用 setTimer 方法，要在失败后调用 destoryTimerbreak;}
}
​
@Override
protected void onDestroy() {super.onDestroy();destoryTimer();
}
​
private Handler handler = new MyHandler(this);
private static class MyHandler extends Handler {private SoftReference<ForgetPasswordActivity> mSoftReference;MyHandler(ForgetPasswordActivity activity) {mSoftReference = new SoftReference<>(activity);}@Overridepublic void handleMessage(Message msg) {super.handleMessage(msg);ForgetPasswordActivity activity = mSoftReference.get();if (activity != null) {switch (msg.what) {case 1:activity.send.setText(activity.time + "s");break;case 2:activity.destoryTimer();break;}}}
}
​
//定时器
private void setTimer() {send.setEnabled(false);//不可点击timer = new Timer();TimerTask task = new TimerTask() {@Overridepublic void run() {time--;if (time > 0) {handler.sendEmptyMessage(1);} else {handler.sendEmptyMessage(2);}}};timer.schedule(task, 0, 1000);//每隔一秒钟执行一次
}
​
private void destoryTimer() {time = 60;//重新倒计时send.setEnabled(true);//重新可点击send.setText("重新发送");//重设文字if (timer != null) {timer.cancel();timer = null;}if (handler!=null) {handler.removeCallbacksAndMessages(null);}
}

@BindView(R.id.send) Button send;//发送验证码
private int time = 60;//倒计时时间
private Timer timer;
​
@OnClick({R.id.send, R.id.next})
public void onClickIv(View v) {switch (v.getId()) {case R.id.send:setTimer();//实际是要在点击之后判断如果符合倒计时条件才调用 setTimer 方法，要在失败后调用 destoryTimerbreak;}
}
​
@Override
protected void onDestroy() {super.onDestroy();destoryTimer();
}
​
private void setTimer() {send.setEnabled(false);TimerTask task = new TimerTask() {@Overridepublic void run() {runOnUiThread(() -> {time--;if (time > 0) {send.setText(time + "s");} else {destoryTimer();}});}};timer = new Timer();timer.schedule(task, 0, 1000);//每隔一秒钟执行一次
}
​
private void destoryTimer() {time = 60;send.setEnabled(true);send.setText("获取验证码");if (timer != null) {timer.cancel();timer = null;}
}

handler.sendMessageDelayed(handler.obtainMessage(1), 1000);
​
final Handler handler = new Handler() {public void handleMessage(Message msg) {switch (msg.what) {case 1:time--;if (time > 0) {send.setText(time + "S");handler.sendMessageDelayed(handler.obtainMessage(1), 1000);//循环发送} else {send.setEnabled(true);send.setText("重新发送");}}}
};

Handler handler = new Handler();
handler.postDelayed(runnable, 1000);
​
Runnable runnable = new Runnable() {@Overridepublic void run() {time--;if (time > 0) {send.setText(time + "S");handler.postDelayed(this, 1000);} else {send.setEnabled(true);send.setText("重新发送");}}
};

compile 'com.github.iwgang:countdownview:2.1.3'

cn.iwgang.countdownview.CountdownView

CountdownView mCountdownView = (CountdownView)findViewById(R.id.countdownView);
mCountdownView.start(995550000); // 毫秒// 或者自己编写倒计时逻辑，然后调用 updateShow 来更新UI
for (int time=0; time<1000; time++) {mCountdownView.updateShow(time);
}

//定时器，用于刷新 GridView 的数据源
private void setQryTimer() {cancelQryTimer(); //取消之前的定时器qryTimer = new Timer(); //重新设置定时器qryTimer.schedule(new TimerTask() {@Overridepublic void run() {runOnUiThread(() -> {if (fixRpList != null && fixRpList.size() > 0) {for (FixRpBean item : fixRpList) {if (item.diff_time >= 0) item.diff_time = item.diff_time - 1000L; //更改数据源}if (fixRpDialog != null) fixRpDialog.upDate(fixRpList); //刷新页面}});}}, 0, 1000); //以固定的周期刷新
}public void upDate(List<FixRpBean> redPacketList) {list.clear(); //情况旧的数据list.addAll(redPacketList); //设置新的数据(如果列表的数据和源数据是同一个集合，也可以直接更新)mRecyclerView.getAdapter().notifyDataSetChanged();//建议使用RecyclerView的局部刷新功能
}

public class RecyclerViewActivity extends Activity {private List<ItemInfo> mDataList;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_recyclerview);initData();RecyclerView recyclerView = (RecyclerView) findViewById(R.id.rv);recyclerView.setAdapter(new MyAdapter(this, mDataList));recyclerView.setLayoutManager(new LinearLayoutManager(this));recyclerView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL));recyclerView.setItemAnimator(new DefaultItemAnimator());}private void initData() {mDataList = new ArrayList<>();for (int i = 1; i < 20; i++) {mDataList.add(new ItemInfo(i * 20 * 1000));}// 校对倒计时long curTime = System.currentTimeMillis();for (ItemInfo itemInfo : mDataList) {itemInfo.endTime = curTime + itemInfo.countdown;}}static class MyAdapter extends RecyclerView.Adapter<MyViewHolder> {private Context mContext;private List<ItemInfo> mDatas;public MyAdapter(Context context, List<ItemInfo> datas) {this.mContext = context;this.mDatas = datas;}@Overridepublic MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {return new MyViewHolder(LayoutInflater.from(mContext).inflate(R.layout.list_item, parent, false));}@Overridepublic void onBindViewHolder(MyViewHolder holder, int position) {holder.bindData(mDatas.get(holder.getAdapterPosition()));}@Overridepublic int getItemCount() {return mDatas.size();}//******************************************** 关键代码 ↓↓ **********************************@Overridepublic void onViewAttachedToWindow(MyViewHolder holder) {super.onViewAttachedToWindow(holder);//父类中为空代码holder.refreshTime(mDatas.get(holder.getAdapterPosition()).endTime - System.currentTimeMillis());}@Overridepublic void onViewDetachedFromWindow(MyViewHolder holder) {super.onViewDetachedFromWindow(holder);holder.countdownView.stop();}//******************************************** 关键代码 ↑↑ **********************************}static class MyViewHolder extends RecyclerView.ViewHolder {public CountdownView countdownView;public MyViewHolder(View itemView) {super(itemView);countdownView = (CountdownView) itemView.findViewById(R.id.countdownView);}public void bindData(ItemInfo itemInfo) {refreshTime(itemInfo.endTime - System.currentTimeMillis());}public void refreshTime(long leftTime) {if (leftTime > 0) {countdownView.start(leftTime);} else {countdownView.stop();//停止计时器，mCustomCountDownTimer.stop();countdownView.allShowZero();//所有计时清零，即mCountdown.setTimes(0, 0, 0, 0, 0);}}}static class ItemInfo {public long countdown;/*根据服务器返回的countdown换算成手机对应的开奖时间 (毫秒)[正常情况最好由服务器返回countdown字段，然后客户端再校对成该手机对应的时间，不然误差很大]*/public long endTime;public ItemInfo(long countdown) {this.countdown = countdown;}}
}

//自己维护倒计时，再调用 countdownView.updateShow 来刷新显示
public class RecyclerViewActivity2 extends AppCompatActivity {private MyAdapter mMyAdapter;private List<ItemInfo> mDataList;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_recyclerview);initData();RecyclerView recyclerView = (RecyclerView) findViewById(R.id.rv);mMyAdapter = new RecyclerViewActivity2.MyAdapter(this, mDataList);recyclerView.setAdapter(mMyAdapter);recyclerView.setLayoutManager(new LinearLayoutManager(this));recyclerView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL));recyclerView.setItemAnimator(new DefaultItemAnimator());}private void initData() {mDataList = new ArrayList<>();for (int i = 1; i < 20; i++) {mDataList.add(new ItemInfo(1000 + i, "RecyclerView_测试标题_" + i, i * 20 * 1000));}// 校对倒计时long curTime = System.currentTimeMillis();for (ItemInfo itemInfo : mDataList) {itemInfo.setEndTime(curTime + itemInfo.getCountdown());}}@Overrideprotected void onResume() {super.onResume();if (null != mMyAdapter) }@Overrideprotected void onPause() {super.onPause();if (null != mMyAdapter) }@Overridepublic void onDestroy() {super.onDestroy();if (null != mMyAdapter) }static class MyAdapter extends RecyclerView.Adapter<MyViewHolder> {private Context mContext;private List<ItemInfo> mDatas;private final SparseArray<MyViewHolder> mCountdownVHList;private Handler mHandler = new Handler();private Timer mTimer;private boolean isCancel = true;public MyAdapter(Context context, List<ItemInfo> datas) {this.mContext = context;this.mDatas = datas;mCountdownVHList = new SparseArray<>();startRefreshTime(); //开启倒计时}public void startRefreshTime() {if (!isCancel) return;if (null != mTimer) mTimer.cancel();isCancel = false;mTimer = new Timer();mTimer.schedule(new TimerTask() {@Overridepublic void run() {mHandler.post(mRefreshTimeRunnable);}}, 0, 10);}public void cancelRefreshTime() {isCancel = true;if (null != mTimer) {mTimer.cancel();}mHandler.removeCallbacks(mRefreshTimeRunnable);}@Overridepublic MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {return new MyViewHolder(LayoutInflater.from(mContext).inflate(R.layout.list_item, parent, false));}@Overridepublic void onBindViewHolder(MyViewHolder holder, int position) {ItemInfo curItemInfo = mDatas.get(position);holder.bindData(curItemInfo);// 处理倒计时if (curItemInfo.getCountdown() > 0) {synchronized (mCountdownVHList) {mCountdownVHList.put(curItemInfo.getId(), holder); //开启倒计时}}}@Overridepublic int getItemCount() {return mDatas.size();}@Overridepublic void onViewRecycled(MyViewHolder holder) {super.onViewRecycled(holder);ItemInfo curAnnounceGoodsInfo = holder.getBean();if (null != curAnnounceGoodsInfo && curAnnounceGoodsInfo.getCountdown() > 0) {mCountdownVHList.remove(curAnnounceGoodsInfo.getId()); //移除}}private Runnable mRefreshTimeRunnable = new Runnable() {@Overridepublic void run() {if (mCountdownVHList.size() == 0) return;synchronized (mCountdownVHList) {long currentTime = System.currentTimeMillis();int key;for (int i = 0; i < mCountdownVHList.size(); i++) {key = mCountdownVHList.keyAt(i);MyViewHolder curMyViewHolder = mCountdownVHList.get(key);if (currentTime >= curMyViewHolder.getBean().getEndTime()) {curMyViewHolder.getBean().setCountdown(0);// 倒计时结束mCountdownVHList.remove(key);notifyDataSetChanged();} else {curMyViewHolder.refreshTime(currentTime); //刷新时间}}}}};}static class MyViewHolder extends RecyclerView.ViewHolder {private TextView mTvTitle;private CountdownView mCvCountdownView;private ItemInfo mItemInfo;public MyViewHolder(View itemView) {super(itemView);mTvTitle = (TextView) itemView.findViewById(R.id.tv_title);mCvCountdownView = (CountdownView) itemView.findViewById(R.id.cv_countdownView);}public void bindData(ItemInfo itemInfo) {mItemInfo = itemInfo;if (itemInfo.getCountdown() > 0) {refreshTime(System.currentTimeMillis());} else {mCvCountdownView.allShowZero();}mTvTitle.setText(itemInfo.getTitle());}public void refreshTime(long curTimeMillis) {if (null == mItemInfo || mItemInfo.getCountdown() <= 0) return;mCvCountdownView.updateShow(mItemInfo.getEndTime() - curTimeMillis);}public ItemInfo getBean() {return mItemInfo;}}static class ItemInfo {private int id;private String title;private long countdown;/*根据服务器返回的countdown换算成手机对应的开奖时间 (毫秒)[正常情况最好由服务器返回countdown字段，然后客户端再校对成该手机对应的时间，不然误差很大]*/private long endTime;public ItemInfo(int id, String title, long countdown) {this.id = id;this.title = title;this.countdown = countdown;}//get、set方法...}}