android - 如何将音频文件延迟几秒钟

Question

我试图弄清楚如何将音频文件延迟大约 15 秒。音频文件有 5 秒长，它是一个声音效果，说“5,4,3,2,1 go！”，倒计时是从 20 开始的，所以它应该在 15 秒后开始。我听说我可以用处理程序来做到这一点，但我不知道如何在代码中实现它，所以在这里，非常感谢帮助！

我用下面的方式编辑了它，但是现在播放器根本没有启动，这是新代码：

public class WorkoutGymEasy1 extends Activity {

CountDownTimer cdt = null;
MediaPlayer mp;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.workout_gym_easy1);

    RelativeLayout rl5 = (RelativeLayout) findViewById(R.id.rl5);
    rl5.setBackgroundColor(Color.BLACK);

     mp = MediaPlayer.create(WorkoutGymEasy1.this, R.raw.countdown);
        try {
            mp.prepare();
        } catch (IllegalStateException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    new CountDownTimer(20000, 1000) { //20 seconds count down with 1s interval (1000 ms)
        TextView c = (TextView) findViewById(R.id.timer_gym_easy1); //access TextView element on the screen to set the timer value

        public void onTick(long millisUntilFinished) { // Code in this method is executed every 1000ms (1s)
            c.setText("" + ((millisUntilFinished / 1000) - 1) + ""); //update the timer
             if(millisUntilFinished == 9000) {
                    mp.start();
                  }
        }

        @Override
        public void onFinish() {
            // TODO Auto-generated method stub
            c.setText("GO!");
            Intent myIntent = new Intent(getApplicationContext(), WorkoutGymEasy2.class);
            startActivity(myIntent);

            finish();               // call finish() method to destroy this activity and return to instructions screen
        }
    }.start();

}

protected void OnPause() {
    super.onPause();
    mp.release();
    finish();
}
}

Answer 1

不要开始播放onCreate() 中的音​​频。从onCreate() 中删除mp.start()。

mp = MediaPlayer.create(WorkoutGymEasy1.this, R.raw.countdown);
try {
  mp.prepare();
} catch (IllegalStateException e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
} catch (IOException e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
}

播放onTick() 中的音​​频。 CountDownTimer 不精确，它会返回尽可能接近 1 秒。它永远不会是 20000、19000... 等等。作为优化，您可以在每个 onTick() 上舍入 millisUntilFinished 并做一个简单的检查，看看您是否应该播放音频。

public void onTick(long millisUntilFinished) { // Code in this method is executed every 1000ms (1s)
  c.setText("" + ((millisUntilFinished / 1000) - 1) + ""); //update the timer
  if(Math.round((float)millisUntilFinished / 1000.0f) == 5) {
    mp.start();
  }
}