public class AudioFxDemo extends Activity {  private static final String TAG = "AudioFxDemo";  private static final float VISUALIZER_HEIGHT_DIP = 50f;  // 定義播放器  private MediaPlayer mMediaPlayer;  // 定義系統(tǒng)的頻譜  private Visualizer mVisualizer;  // 定義系統(tǒng)的均衡器  private Equalizer mEqualizer;  private LinearLayout mLinearLayout;  private VisualizerView mVisualizerView;  private TextView mStatusTextView;  @Override  public void onCreate(Bundle bundle) {    super.onCreate(bundle);    // 音量控制    setVolumeControlStream(AudioManager.STREAM_MUSIC);    mStatusTextView = new TextView(this);    mLinearLayout = new LinearLayout(this);    mLinearLayout.setOrientation(LinearLayout.VERTICAL);    mLinearLayout.addView(mStatusTextView);    setContentView(mLinearLayout);    // 創(chuàng)建MediaPlayer對象    mMediaPlayer = MediaPlayer.create(this, R.raw.test_cbr);    Log.d(TAG,        "MediaPlayer audio session ID: "            + mMediaPlayer.getAudioSessionId());    // 設置頻譜顯示    setupVisualizerFxAndUI();    // 設置示波器顯示    setupEqualizerFxAndUI();    // Make sure the visualizer is enabled only when you actually want to    // receive data, and    // when it makes sense to receive data.    mVisualizer.setEnabled(true);    // When the stream ends, we don't need to collect any more data. We    // don't do this in    // setupVisualizerFxAndUI because we likely want to have more,    // non-Visualizer related code    // in this callback.    mMediaPlayer        .setOnCompletionListener(new MediaPlayer.OnCompletionListener() {          public void onCompletion(MediaPlayer mediaPlayer) {            mVisualizer.setEnabled(false);            mStatusTextView.setText("播放結(jié)束");          }        });    mMediaPlayer.start();    mStatusTextView.setText("正在播放中");  }  private void setupEqualizerFxAndUI() {    // Create the Equalizer object (an AudioEffect subclass) and attach it    // to our media player,    // with a default priority (0).    mEqualizer = new Equalizer(0, mMediaPlayer.getAudioSessionId());    mEqualizer.setEnabled(true);    TextView eqTextView = new TextView(this);    eqTextView.setText("Equalizer:");    mLinearLayout.addView(eqTextView);    short bands = mEqualizer.getNumberOfBands();    final short minEQLevel = mEqualizer.getBandLevelRange()[0];    final short maxEQLevel = mEqualizer.getBandLevelRange()[1];    for (short i = 0; i < bands; i++) {      final short band = i;      TextView freqTextView = new TextView(this);      freqTextView.setLayoutParams(new ViewGroup.LayoutParams(          ViewGroup.LayoutParams.MATCH_PARENT,          ViewGroup.LayoutParams.WRAP_CONTENT));      freqTextView.setGravity(Gravity.CENTER_HORIZONTAL);      freqTextView.setText((mEqualizer.getCenterFreq(band) / 1000)          + " Hz");      mLinearLayout.addView(freqTextView);      LinearLayout row = new LinearLayout(this);      row.setOrientation(LinearLayout.HORIZONTAL);      TextView minDbTextView = new TextView(this);      minDbTextView.setLayoutParams(new ViewGroup.LayoutParams(          ViewGroup.LayoutParams.WRAP_CONTENT,          ViewGroup.LayoutParams.WRAP_CONTENT));      minDbTextView.setText((minEQLevel / 100) + " dB");      TextView maxDbTextView = new TextView(this);      maxDbTextView.setLayoutParams(new ViewGroup.LayoutParams(          ViewGroup.LayoutParams.WRAP_CONTENT,          ViewGroup.LayoutParams.WRAP_CONTENT));      maxDbTextView.setText((maxEQLevel / 100) + " dB");      LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(          ViewGroup.LayoutParams.MATCH_PARENT,          ViewGroup.LayoutParams.WRAP_CONTENT);      layoutParams.weight = 1;      SeekBar bar = new SeekBar(this);      bar.setLayoutParams(layoutParams);      bar.setMax(maxEQLevel - minEQLevel);      bar.setProgress(mEqualizer.getBandLevel(band));      bar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {        public void onProgressChanged(SeekBar seekBar, int progress,            boolean fromUser) {          mEqualizer.setBandLevel(band,              (short) (progress + minEQLevel));        }        public void onStartTrackingTouch(SeekBar seekBar) {        }        public void onStopTrackingTouch(SeekBar seekBar) {        }      });      row.addView(minDbTextView);      row.addView(bar);      row.addView(maxDbTextView);      mLinearLayout.addView(row);    }  }  private void setupVisualizerFxAndUI() {    // Create a VisualizerView (defined below), which will render the    // simplified audio    // wave form to a Canvas.    mVisualizerView = new VisualizerView(this);    mVisualizerView.setLayoutParams(new ViewGroup.LayoutParams(        ViewGroup.LayoutParams.MATCH_PARENT,        (int) (VISUALIZER_HEIGHT_DIP * getResources()            .getDisplayMetrics().density)));    mLinearLayout.addView(mVisualizerView);    // Create the Visualizer object and attach it to our media player.    mVisualizer = new Visualizer(mMediaPlayer.getAudioSessionId());    mVisualizer.setCaptureSize(Visualizer.getCaptureSizeRange()[1]);    mVisualizer.setDataCaptureListener(        new Visualizer.OnDataCaptureListener() {          public void onWaveFormDataCapture(Visualizer visualizer,              byte[] bytes, int samplingRate) {            mVisualizerView.updateVisualizer(bytes);          }          public void onFftDataCapture(Visualizer visualizer,              byte[] bytes, int samplingRate) {          }        }, Visualizer.getMaxCaptureRate() / 2, true, false);  }  @Override  protected void onPause() {    super.onPause();    if (isFinishing() && mMediaPlayer != null) {      mVisualizer.release();      mEqualizer.release();      mMediaPlayer.release();      mMediaPlayer = null;    }  }}/** * 繪制波狀View *  * @description： * @author ldm * @date 2016-4-20 上午9:11:49 */class VisualizerView extends View {  // 數(shù)組保存了波形抽樣點的值  private byte[] bytes;  private float[] points;  // 定義畫筆  private Paint paint = new Paint();  // 矩形區(qū)域  private Rect rect = new Rect();  private byte type = 0;  public VisualizerView(Context context) {    super(context);    bytes = null;    // 設置畫筆的屬性    paint.setStrokeWidth(1f);// 設置空心線寬    paint.setAntiAlias(true);// 抗鋸齒    paint.setColor(Color.BLUE);// 畫筆顏色    paint.setStyle(Style.STROKE);// 非填充模式  }  public void updateVisualizer(byte[] ftt) {    bytes = ftt;    // 通知組件重繪    invalidate();  }  @Override  public boolean onTouchEvent(MotionEvent me) {    // 當用戶觸碰該組件時，切換波形類型    if (me.getAction() != MotionEvent.ACTION_DOWN) {      return false;    }    type++;    if (type >= 3) {      type = 0;    }    return true;  }  @Override  protected void onDraw(Canvas canvas) {    super.onDraw(canvas);    if (bytes == null) {      return;    }    // 繪制黑色背景    canvas.drawColor(Color.BLACK);    // 使用rect對象記錄該組件的寬度和高度    rect.set(0, 0, getWidth(), getHeight());    switch (type) {    // 繪制塊狀的波形圖    case 0:      for (int i = 0; i < bytes.length - 1; i++) {        float left = getWidth() * i / (bytes.length - 1);        // 根據(jù)波形值計算該矩形的高度        float top = rect.height() - (byte) (bytes[i + 1] + 128)            * rect.height() / 128;        float right = left + 1;        float bottom = rect.height();        canvas.drawRect(left, top, right, bottom, paint);      }      break;    // 繪制柱狀的波形圖（每隔18個抽樣點繪制一個矩形）    case 1:      for (int i = 0; i < bytes.length - 1; i += 18) {        float left = rect.width() * i / (bytes.length - 1);        // 根據(jù)波形值計算該矩形的高度        float top = rect.height() - (byte) (bytes[i + 1] + 128)            * rect.height() / 128;        float right = left + 6;        float bottom = rect.height();        canvas.drawRect(left, top, right, bottom, paint);      }      break;    // -繪制曲線波形圖    case 2:      // 如果point數(shù)組還未初始化      if (points == null || points.length < bytes.length * 4) {        points = new float[bytes.length * 4];      }      for (int i = 0; i < bytes.length - 1; i++) {        // 計算第i個點的x坐標        points[i * 4] = rect.width() * i / (bytes.length - 1);        // 根據(jù)bytes[i]的值（波形點的值）計算第i個點的y坐標        points[i * 4 + 1] = (rect.height() / 2)            + ((byte) (bytes[i] + 128)) * 128 / (rect.height() / 2);        // 計算第i+1個點的x坐標        points[i * 4 + 2] = rect.width() * (i + 1) / (bytes.length - 1);        // 根據(jù)bytes[i+1]的值（波形點的值）計算第i+1個點的y坐標        points[i * 4 + 3] = (rect.height() / 2)            + ((byte) (bytes[i + 1] + 128)) * 128            / (rect.height() / 2);      }      // 繪制波形曲線      canvas.drawLines(points, paint);      break;    }  }}