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(duì)象
    mMediaPlayer = MediaPlayer.create(this, R.raw.test_cbr);
    Log.d(TAG,
        "MediaPlayer audio session ID: "
            + mMediaPlayer.getAudioSessionId());
    // 設(shè)置頻譜顯示
    setupVisualizerFxAndUI();
    // 設(shè)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(diǎn)的值
  private byte[] bytes;
  private float[] points;
  // 定義畫(huà)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(shè)置畫(huà)筆的屬性
    paint.setStrokeWidth(1f);// 設(shè)置空心線寬
    paint.setAntiAlias(true);// 抗鋸齒
    paint.setColor(Color.BLUE);// 畫(huà)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(dāng)用戶(hù)觸碰該組件時(shí)，切換波形類(lèi)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(duì)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(jì)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(gè)抽樣點(diǎn)繪制一個(gè)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(jì)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(jì)算第i個(gè)點(diǎn)的x坐標(biāo)
        points[i * 4] = rect.width() * i / (bytes.length - 1);
        // 根據(jù)bytes[i]的值（波形點(diǎn)的值）計(jì)算第i個(gè)點(diǎn)的y坐標(biāo)
        points[i * 4 + 1] = (rect.height() / 2)
            + ((byte) (bytes[i] + 128)) * 128 / (rect.height() / 2);
        // 計(jì)算第i+1個(gè)點(diǎn)的x坐標(biāo)
        points[i * 4 + 2] = rect.width() * (i + 1) / (bytes.length - 1);
        // 根據(jù)bytes[i+1]的值（波形點(diǎn)的值）計(jì)算第i+1個(gè)點(diǎn)的y坐標(biāo)
        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;
    }
  }
}