Android编程之播放器MediaPlayer实现均衡器效果示例

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;
    }
  }
}
/**
 * 绘制波状view
 * 
 * @description：
 * @author ldm
 * @date 2016-4-20 上午9:11:49
 */
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。