首先说下对于handler本身的误差：
如果应用handler.postDealyed(……, 1000)形式来进行每秒的计时，是不精确的，是的，有很大误差，误差的起因在于在你收到音讯，到你从新收回handler.postDealyed的工夫，并不是霎时实现的，这外面有很多逻辑解决的工夫，即便没有逻辑解决的工夫，handler自身也是耗损性能的，所以音讯并不可能依照现实的1000提早来进行发送，这就导致了误差的累积。
代码:
时钟接口：
public interface IDigitalClock { /** * 开始计时 */ void start(); /** * 进行 */ void stop(); /** * 时钟复位 */ void reset(); /** * 重启 */ void restart();}正计时时钟：
import android.os.Handler;import android.os.Looper;import android.os.Message;import android.os.SystemClock;import android.util.Log;import java.text.DecimalFormat;public class DefaultDigitalClock implements IDigitalClock { private final static String TAG = "DefaultDigitalClock"; private final static int TICK_EVENT = 0x1001; private Ticker mTicker; private Handler handler = new Handler(new Handler.Callback() { @Override public boolean handleMessage(Message msg) { if (msg.what == TICK_EVENT) { long seconds = (long) msg.obj; String HHMMss = formatElapsedTime(seconds); clock.tick(seconds, HHMMss); } return false; } }); private long startTime; private long elapsedSeconds; private long maxSeconds; private ClockOnMainThread clock; public DefaultDigitalClock(ClockOnMainThread clock) { this(-1, clock); } public DefaultDigitalClock(long maxSeconds, ClockOnMainThread clock) { this.maxSeconds = maxSeconds; this.clock = clock; this.elapsedSeconds = -1; this.startTime = -1; } @Override public void start() { startTime = System.currentTimeMillis(); mTicker = new Ticker(); long now = SystemClock.uptimeMillis(); long next = now + (1000 - now % 1000); handler.postAtTime(mTicker, next); } @Override public void stop() { handler.removeMessages(TICK_EVENT); if (mTicker != null) { handler.removeCallbacks(mTicker); } } @Override public void reset() { elapsedSeconds = -1; startTime = -1; handler.sendMessage(newTick(0)); } @Override public void restart() { stop(); reset(); start(); } /** * 在每秒的整点执行 * {@link "https://blog.csdn.net/cpcpcp123/article/details/88542113"} */ private final class Ticker implements Runnable { public void run() { onTimeChanged(); // 在设定秒数后完结 if (maxSeconds > 0 && elapsedSeconds == maxSeconds) { stop(); return; } long now = SystemClock.uptimeMillis(); long next = now + (1000 - now % 1000); handler.postAtTime(this, next); } }; /** * 计算工夫变动 */ private void onTimeChanged() { if (Thread.currentThread() != Looper.getMainLooper().getThread()) { Log.e(TAG, "onTimeChanged() must work on main thread!"); return; } elapsedSeconds = (System.currentTimeMillis() - startTime) / 1000; Log.d(TAG, String.valueOf(elapsedSeconds)); String HHMMss = formatElapsedTime(elapsedSeconds); clock.tick(elapsedSeconds, HHMMss); } private Message newTick(long seconds) { Message msg = new Message(); msg.what = TICK_EVENT; msg.obj = seconds; return msg; } /** * @see android.text.format.DateUtils#formatElapsedTime(long) * @param elapsedSeconds 通过的秒数 */ private String formatElapsedTime(long elapsedSeconds) { // Break the elapsed seconds into hours, minutes, and seconds. long hours = 0; long minutes = 0; long seconds = 0; if (elapsedSeconds >= 3600) { hours = elapsedSeconds / 3600; elapsedSeconds -= hours * 3600; } if (elapsedSeconds >= 60) { minutes = elapsedSeconds / 60; elapsedSeconds -= minutes * 60; } seconds = elapsedSeconds; String hh = new DecimalFormat("00").format(hours); String mm = new DecimalFormat("00").format(minutes); String ss = new DecimalFormat("00").format(seconds); return String.format("%s:%s:%s", hh, mm, ss); } public interface ClockOnMainThread { void tick(long seconds, String time); }}参考博客
- handler实现准确计时的两种形式
- Android计时罕用的7种形式