Android 秒表 Demo 介绍

1. Android 秒表 Demo

代码主要从系统-时钟的秒表模块截取。

主要原理：View事件的PostRunable进行时间和UI的更新，不同于我们常用的Thread+延时， Handle + 延时和TimeTask定时，起码我第一次看还是觉得很神奇

StopWatch

2. GitHub demo下载

https://github.com/sufadi/SuStopwatch

3. 源码方法

3.1 秒表开始

主要进行秒表开始和UI的状态切换，主要核心是 mTime.post(mTimeUpdateRunnable); 进行触发

    /**
     * Start the stopwatch.
     */
    public void doStart(View view) {
        // Update the stopwatch state. 更新数据库状态
        DataModel.getDataModel().startStopwatch();

        // Start UI updates.
        startUpdatingTime();
        mTime.update();
        mTimeText.blinkTimeStr(false);

        // Acquire the wake lock.防止CPU休眠，导致不刷新时间
        acquireWakeLock();
    }

    /**
     * Post the first runnable to update times within the UI. It will reschedule
     * itself as needed.
     */
    private void startUpdatingTime() {
        // Ensure only one copy of the runnable is ever scheduled by first
        // stopping updates.
        stopUpdatingTime();
        mTime.post(mTimeUpdateRunnable);
    }

3.2 设置Runnable定时

    /**
     * This runnable periodically updates times throughout the UI. It stops
     * these updates when the stopwatch is no longer running.
     */
    private final class TimeUpdateRunnable implements Runnable {
        @Override
        public void run() {
            Log.d("suhuazhi", "TimeUpdateRunnable");
            final long startTime = SystemClock.elapsedRealtime();

            updateTime();

            if (getStopwatch().isRunning()) {
                // The stopwatch is still running so execute this runnable again
                // after a delay.
                final boolean talkBackOn = true;

                // Grant longer time between redraws when talk-back is on to let
                // it catch up.
                final int period = talkBackOn ? 500 : 25;

                // Try to maintain a consistent period of time between redraws.
                final long endTime = SystemClock.elapsedRealtime();
                final long delay = Math.max(0, startTime + period - endTime);

                mTime.postDelayed(this, delay);
            }
        }
    }

3.3 秒表暂停

核心自定View 进行 mTime.removeCallbacks(mTimeUpdateRunnable) 即可

    /**
     * Pause the stopwatch.
     */
    public void doPause(View view) {
        // Update the stopwatch state
        DataModel.getDataModel().pauseStopwatch();

        // Redraw the paused stopwatch time.
        updateTime();

        // Stop UI updates.
        stopUpdatingTime();
        mTimeText.blinkTimeStr(true);
    }

    /**
     * Remove the runnable that updates times within the UI.
     */
    private void stopUpdatingTime() {
        mTime.removeCallbacks(mTimeUpdateRunnable);
    }

3.4 秒表的复位

记得是否CPU唤醒锁，将数据库秒表数据重新初始化即可

    /**
     * Reset the stopwatch.
     */
    public void doReset(View view) {
        // Update the stopwatch state.
        DataModel.getDataModel().resetStopwatch();
        // Clear the times.
        mTimeText.setTime(0, true, true);
        // Release the wake lock.
        releaseWakeLock();
    }