Android播放PCM，请写出代码

以下是一份简单的 Android 播放 PCM 的代码：

import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioTrack;

public class PCMPlayer {
    private AudioTrack audioTrack;
    private Thread playThread;

    public PCMPlayer() {
        int sampleRateInHz = 44100;
        int channelConfig = AudioFormat.CHANNEL_OUT_MONO;
        int audioFormat = AudioFormat.ENCODING_PCM_16BIT;
        int bufferSizeInBytes = AudioTrack.getMinBufferSize(sampleRateInHz, channelConfig, audioFormat);

        audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, sampleRateInHz, channelConfig, audioFormat, bufferSizeInBytes, AudioTrack.MODE_STREAM);
    }

    public void start() {
        playThread = new Thread(new Runnable() {
            @Override
            public void run() {
                audioTrack.play();
                // TODO: 将 PCM 数据写入 audioTrack
            }
        });
        playThread.start();
    }

    public void stop() {
        if (audioTrack != null) {
            audioTrack.stop();
            audioTrack.release();
            audioTrack = null;
        }
        if (playThread != null) {
            try {
                playThread.join();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            playThread = null;
        }
    }
}

这份代码创建了一个 `AudioTrack` 对象，并在 `start` 方法中启动一个新的线程，用于播放 PCM 数据。你需要在此方法中将 PCM 数据写入 `audioTrack`。`stop` 方法用于停止播放并释放资源。