public class MediaRecorderDemo {  private final String TAG = "MediaRecord";  private MediaRecorder mMediaRecorder;  public static final int MAX_LENGTH = 1000 * 60 * 10;// 最大录音时长1000*60*10;  private String filePath;  public MediaRecorderDemo(){  this.filePath = "/dev/null";  }  public MediaRecorderDemo(File file) {  this.filePath = file.getAbsolutePath();  }  private long startTime;  private long endTime;  /** * 开始录音 使用amr格式 * *            录音文件 * @return */  public void startRecord() {  // 开始录音  /* ①Initial：实例化MediaRecorder对象 */  if (mMediaRecorder == null)  mMediaRecorder = new MediaRecorder();  try {  /* ②setAudioSource/setVedioSource */  mMediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);// 设置麦克风  /* ②设置音频文件的编码：AAC/AMR_NB/AMR_MB/Default 声音的（波形）的采样 */  mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.DEFAULT);  /* * ②设置输出文件的格式：THREE_GPP/MPEG-4/RAW_AMR/Default THREE_GPP(3gp格式 * ，H263视频/ARM音频编码)、MPEG-4、RAW_AMR(只支持音频且音频编码要求为AMR_NB) */  mMediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);  /* ③准备 */  mMediaRecorder.setOutputFile(filePath);  mMediaRecorder.setMaxDuration(MAX_LENGTH);  mMediaRecorder.prepare();  /* ④开始 */  mMediaRecorder.start();  // AudioRecord audioRecord.  /* 获取开始时间* */  startTime = System.currentTimeMillis();  updateMicStatus();  Log.i("ACTION_START", "startTime" + startTime);  } catch (IllegalStateException e) {  Log.i(TAG,  "call startAmr(File mRecAudioFile) failed!"  + e.getMessage());  } catch (IOException e) {  Log.i(TAG,  "call startAmr(File mRecAudioFile) failed!"  + e.getMessage());  }  }  /** * 停止录音 * */  public long stopRecord() {  if (mMediaRecorder == null)  return 0L;  endTime = System.currentTimeMillis();  Log.i("ACTION_END", "endTime" + endTime);  mMediaRecorder.stop();  mMediaRecorder.reset();  mMediaRecorder.release();  mMediaRecorder = null;  Log.i("ACTION_LENGTH", "Time" + (endTime - startTime));  return endTime - startTime;  }  private final Handler mHandler = new Handler();  private Runnable mUpdateMicStatusTimer = new Runnable() {  public void run() {  updateMicStatus();  }  };  /** * 更新话筒状态 * */  private int BASE = 1;  private int SPACE = 100;// 间隔取样时间  private void updateMicStatus() {  if (mMediaRecorder != null) {  double ratio = (double)mMediaRecorder.getMaxAmplitude() /BASE;  double db = 0;// 分贝  if (ratio > 1)  db = 20 * Math.log10(ratio);  Log.d(TAG,"分贝值："+db);  mHandler.postDelayed(mUpdateMicStatusTimer, SPACE);  }  }
}