本文实例讲述了Android播放器MediaPlayer实现均衡器效果。分享给大家供大家参考，具体如下：
这几天在系统学习Android官方API Demos，看到实现均衡器效果，就把官方API中代码copy下来，根据网上前辈的指引略有修改，添加了注释。
public class AudioFxDemo extends Activity {
private static final String TAG = "AudioFxDemo";
private static final float VISUALIZER_HEIGHT_DIP = 50f;
// 定义播放器
private MediaPlayer mMediaPlayer;
// 定义系统的频谱
private Visualizer mVisualizer;
// 定义系统的均衡器
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);
// 创建MediaPlayer对象
mMediaPlayer = MediaPlayer.create(this, R.raw.test_cbr);
Log.d(TAG,
"MediaPlayer audio session ID: "
+ mMediaPlayer.getAudioSessionId());
// 设置频谱显示
setupVisualizerFxAndUI();
// 设置示波器显示
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("播放结束");
}
});
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;
}
}
}
class VisualizerView extends View {
// 数组保存了波形抽样点的值
private byte[] bytes;
private float[] points;
// 定义画笔
private Paint paint = new Paint();
// 矩形区域
private Rect rect = new Rect();
private byte type = 0;
public VisualizerView(Context context) {
super(context);
bytes = null;
// 设置画笔的属性
paint.setStrokeWidth(1f);// 设置空心线宽
paint.setAntiAlias(true);// 抗锯齿
paint.setColor(Color.BLUE);// 画笔颜色
paint.setStyle(Style.STROKE);// 非填充模式
}
public void updateVisualizer(byte[] ftt) {
bytes = ftt;
// 通知组件重绘
invalidate();
}
@Override
public boolean onTouchEvent(MotionEvent me) {
// 当用户触碰该组件时，切换波形类型
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;
}
// 绘制黑色背景
canvas.drawColor(Color.BLACK);
// 使用rect对象记录该组件的宽度和高度
rect.set(0, 0, getWidth(), getHeight());
switch (type) {
// 绘制块状的波形图
case 0:
for (int i = 0; i < bytes.length - 1; i++) {
float left = getWidth() * i / (bytes.length - 1);
// 根据波形值计算该矩形的高度
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;
// 绘制柱状的波形图（每隔18个抽样点绘制一个矩形）
case 1:
for (int i = 0; i < bytes.length - 1; i += 18) {
float left = rect.width() * i / (bytes.length - 1);
// 根据波形值计算该矩形的高度
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;
// -绘制曲线波形图
case 2:
// 如果point数组还未初始化
if (points == null || points.length < bytes.length * 4) {
points = new float[bytes.length * 4];
}
for (int i = 0; i < bytes.length - 1; i++) {
// 计算第i个点的x坐标
points[i * 4] = rect.width() * i / (bytes.length - 1);
// 根据bytes[i]的值（波形点的值）计算第i个点的y坐标
points[i * 4 + 1] = (rect.height() / 2)
+ ((byte) (bytes[i] + 128)) * 128 / (rect.height() / 2);
// 计算第i+1个点的x坐标
points[i * 4 + 2] = rect.width() * (i + 1) / (bytes.length - 1);
// 根据bytes[i+1]的值（波形点的值）计算第i+1个点的y坐标
points[i * 4 + 3] = (rect.height() / 2)
+ ((byte) (bytes[i + 1] + 128)) * 128
/ (rect.height() / 2);
}
// 绘制波形曲线
canvas.drawLines(points, paint);
break;
}
}
}
自己新建 项目时，记得在res/raw下添加一个名为test_cbr的mp3格式文件。
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希望本文所述对大家Android程序设计有所帮助。
