播放录音文件波形图

public class AudioNoteActivity extends Activity {


    // Here is your URL defined
    String url = "http://vprbbc.streamguys.net/vprbbc24.mp3";


    // Constants for vizualizator - HEIGHT 50dip
    private static final float VISUALIZER_HEIGHT_DIP = 50f;


    // Your MediaPlayer
    MediaPlayer mp;


    // Vizualization
    private Visualizer mVisualizer;


    private LinearLayout mLinearLayout;


    private VisualizerView mVisualizerView;


    private TextView mStatusTextView;
    
    private String mRecordAudioFile = null;


    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_audio_note);


        // Info textView
        mStatusTextView = new TextView(this);


        // Create new LinearLayout ( because main.xml is empty )
        mLinearLayout = new LinearLayout(this);
        mLinearLayout.setOrientation(LinearLayout.VERTICAL);
        mLinearLayout.addView(mStatusTextView);


        // set content view to new Layout that we create
        setContentView(mLinearLayout);


        // start media player - like normal
        mp = new MediaPlayer();
//        mp.setAudioStreamType(AudioManager.STREAM_MUSIC);


        Intent intent = getIntent();

        if(intent.hasExtra("path_audio_record")) {

// 获取录音文件路径名

            mRecordAudioFile = intent.getStringExtra("path_audio_record");
        }
        
        try {
            Uri media = Uri.parse(mRecordAudioFile);
            mp = MediaPlayer.create(AudioNoteActivity.this, media);
            mp.setAudioStreamType(AudioManager.STREAM_MUSIC);
            mp.setDataSource(url); // set data source our URL defined
        } catch (IllegalArgumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IllegalStateException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }


        try { // tell your player to go to prepare state
            mp.prepare();
        } catch (IllegalStateException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        // Start your stream / player
        mp.start();


        // setup your Vizualizer - call method
        setupVisualizerFxAndUI();


        // enable vizualizer
        mVisualizer.setEnabled(true);


        // Info text
        mStatusTextView.setText("Playing audio...");
    }


    // Our method that sets Vizualizer
    private void setupVisualizerFxAndUI() {
        // Create a VisualizerView (defined below), which will render the
        // simplified audio
        // wave form to a Canvas.


        // You need to have something where to show Audio WAVE - in this case
        // Canvas
        mVisualizerView = new VisualizerView(this);
        mVisualizerView.setLayoutParams(new ViewGroup.LayoutParams(
                ViewGroup.LayoutParams.FILL_PARENT, (int) (VISUALIZER_HEIGHT_DIP * getResources()
                        .getDisplayMetrics().density)));
        mLinearLayout.addView(mVisualizerView);


        // Create the Visualizer object and attach it to our media player.
        // YOU NEED android.permission.RECORD_AUDIO for that in
        // AndroidManifest.xml
        mVisualizer = new Visualizer(mp.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() && mp != null) {
            mVisualizer.release();
//            mEqualizer.release();
            mp.release();
            mp = null;
        }
    }


    /**
     * A simple class that draws waveform data received from a
     * {@link Visualizer.OnDataCaptureListener#onWaveFormDataCapture }
     */
    class VisualizerView extends View {
        private byte[] mBytes;


        private float[] mPoints;


        private Rect mRect = new Rect();


        private Paint mForePaint = new Paint();


        public VisualizerView(Context context) {
            super(context);
            init();
        }


        private void init() {
            mBytes = null;


            mForePaint.setStrokeWidth(3f);
            mForePaint.setAntiAlias(true);
            mForePaint.setDither(true);
            mForePaint.setColor(Color.rgb(0, 128, 255));
        }


        public void updateVisualizer(byte[] bytes) {
            mBytes = bytes;
            invalidate();
        }


        @Override
        protected void onDraw(Canvas canvas) {
            super.onDraw(canvas);


            if (mBytes == null) {
                return;
            }


            if (mPoints == null || mPoints.length < mBytes.length * 4) {
                mPoints = new float[mBytes.length * 4];
            }


            mRect.set(0, 0, getWidth(), getHeight());


            for (int i = 0; i < mBytes.length - 1; i++) {
                mPoints[i * 4] = mRect.width() * i / (mBytes.length - 1);
                mPoints[i * 4 + 1] = mRect.height() / 2 + ((byte) (mBytes[i] + 128))
                        * (mRect.height() / 2) / 128;
                mPoints[i * 4 + 2] = mRect.width() * (i + 1) / (mBytes.length - 1);
                mPoints[i * 4 + 3] = mRect.height() / 2 + ((byte) (mBytes[i + 1] + 128))
                        * (mRect.height() / 2) / 128;
            }


            canvas.drawLines(mPoints, mForePaint);
        }
    }
}

注意事项：Visualizer 这个类只在2.3及以上系统中有，