AudioRecord 类的问题

Question

我正在使用 AudioRecord 类录制音频。我想将音频录制到我的资产文件夹或资源文件夹中的特定文件中。我认为录制没有问题。但是在读取缓冲区时它显示了一些问题（它正在抛出NullPointerException)。谁能提出可能是什么问题？

Answer 1

您不能在 Asset 文件夹中保存文件。 Assets 文件夹是只读的，您必须将其保存在设备的内部或外部存储中

下面有一个核心用来记录媒体文件。

package com.example.media.record;

    import java.io.File;
    import java.io.IOException;

    import android.app.Activity;
    import android.media.MediaPlayer;
    import android.media.MediaPlayer.OnCompletionListener;
    import android.media.MediaPlayer.OnErrorListener;
    import android.media.MediaRecorder;
    import android.os.Bundle;
    import android.os.Environment;
    import android.os.Handler;
    import android.os.Handler.Callback;
    import android.os.Message;
    import android.view.View;
    import android.view.View.OnClickListener;
    import android.widget.Button;
    import android.widget.ProgressBar;
    import android.widget.Toast;

    public class MediaRecorderActivity extends Activity implements OnClickListener {
        Button btnPlay;
        Button btnRecord;
        ProgressBar progress;
        MediaPlayer mPlayer;
        MediaRecorder mRecorder;
        String mFileName;
        boolean mStartRecording = true;
        boolean mStartPlaying = true;
        Thread mThreadProgress;
        int duration = 1;
        private void onRecord(boolean start) {
            if(start) {
                startRecording();
            }else {
                stopRecording();
            }
        }

        private void onPlay(boolean start) {
            if(start) {
                startPlaying();
            }else {
                stopPlaying();
            }
        }

        private void startRecording() {
            mRecorder = new MediaRecorder();
            mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
            mRecorder.setOutputFile(mFileName);
            mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
            mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
            mRecorder.setOnErrorListener(errorListenerForRecorder);

            try {
                mRecorder.prepare();
            } catch (IllegalStateException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                mRecorder.start();
            } catch (Exception e) {
                Toast.makeText(getApplicationContext(), "Error :: " + e.getMessage(), Toast.LENGTH_LONG).show();
            }

        }


        private void stopRecording() {
            if(mRecorder != null) {
                mRecorder.stop();
                mRecorder.release();
                mRecorder = null;
            }
        }

        private void startPlaying() {
            mPlayer = new MediaPlayer();
            try {
                mPlayer.setDataSource(mFileName);
                mPlayer.setOnCompletionListener(completionListener);
                mPlayer.setOnErrorListener(errorListenerForPlayer);
                mPlayer.prepare();
                mPlayer.start();
            } catch (IllegalArgumentException e) {
                e.printStackTrace();
            } catch (IllegalStateException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
        private void stopPlaying() {
            if(mPlayer != null) {
                mPlayer.stop();
                mPlayer.release();
                mPlayer = null;
            }
        }

        OnCompletionListener completionListener = new OnCompletionListener() {

            @Override
            public void onCompletion(MediaPlayer mp) {
                btnRecord.setEnabled(true);
                btnPlay.setText("Start playing");
                mStartPlaying = !mStartPlaying;
            }
        };

        OnErrorListener errorListenerForPlayer = new OnErrorListener() {

            @Override
            public boolean onError(MediaPlayer mp, int what, int extra) {
                Toast.makeText(getApplicationContext(), "Error during playing file", 3000).show();
                return false;
            }
        };

        android.media.MediaRecorder.OnErrorListener errorListenerForRecorder = new android.media.MediaRecorder.OnErrorListener() {

            @Override
            public void onError(MediaRecorder mr, int what, int extra) {
                Toast.makeText(getApplicationContext(), "Error during recoding file", 3000).show();

            }
        };
        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);
            btnPlay = (Button)findViewById(R.id.btnPlay);
            btnRecord = (Button)findViewById(R.id.btnRecord);
            progress = (ProgressBar)findViewById(R.id.progressRecorder);
            mFileName = Environment.getExternalStorageDirectory().getAbsolutePath();
            mFileName += "/audiorecordtest.3gp";
            File file = new File(mFileName);
            if(!file.exists()) btnPlay.setEnabled(false); 
            btnPlay.setOnClickListener(this);
            btnRecord.setOnClickListener(this);
        }

        @Override
        protected void onPause() {
            super.onPause();
            if(mRecorder != null) {
                mRecorder.stop();
            }
            if(mPlayer != null) {
                mPlayer.pause();
            }
        }


        @Override
        protected void onResume() {
            super.onResume();
            if(mRecorder != null) {
                mRecorder.start();
            }
            if(mPlayer != null) {
                mPlayer.start();
            }
        }

        @Override
        protected void onStop() {
            super.onStop();
            if(mRecorder != null) {
                mRecorder.stop();
            }
            if(mPlayer != null) {
                mPlayer.stop();
            }
        }

        @Override
        protected void onDestroy() {
            super.onDestroy();
            if(mRecorder != null) {
                mRecorder.release();
                mRecorder = null;
            }
            if(mPlayer != null) {
                mPlayer.release();
                mPlayer = null;
            }
        }

        @Override
        public void onClick(View v) {

            if(v == btnPlay) {

                onPlay(mStartPlaying);
                if(mStartPlaying) {
                    duration = mPlayer.getDuration();
                    mThreadProgress = new ThreadProgress();
                    mThreadProgress.start();
                    ((Button)v).setText("Stop Playing");
                    btnRecord.setEnabled(false);

                }
                else {
                    ((Button)v).setText("Start Playing");
                    btnRecord.setEnabled(true);
                    if(mThreadProgress != null && !mThreadProgress.isAlive()) mThreadProgress.stop();

                    //  t.interrupt();
                }
                mStartPlaying = !mStartPlaying;

            } else if(v == btnRecord) {
                onRecord(mStartRecording);
                if(mStartRecording) {
                    mThreadProgress = new ThreadProgress();
                    mThreadProgress.start();
                    ((Button)v).setText("Stop Recording");
                    btnPlay.setEnabled(false);
                    //  t.start();
                }
                else {
                    ((Button)v).setText("Start Recording");
                    btnPlay.setEnabled(true);
                    //  t.interrupt();
                    if(mThreadProgress != null && !mThreadProgress.isAlive()) mThreadProgress.stop();
                }
                mStartRecording = !mStartRecording;
            }
        }


        Handler handler = new Handler(new Callback() {

            @Override
            public boolean handleMessage(final Message msg) {
                if(msg.what == 0) {
                    runOnUiThread(new Runnable() {
                        public void run() {
                            progress.setProgress(msg.arg1);
                        }
                    });

                }
                return false;
            }
        });

        public class ThreadProgress extends Thread implements Runnable {

            public int i = 0;
            @Override
            public void run() {
                while((!this.isInterrupted() && mPlayer != null && mPlayer.isPlaying()) || (!this.isInterrupted() && mRecorder != null)) {
                    try {
                        if(duration == 1) i+=1;
                        else i += 100000 /duration;
                        Message message = new Message();
                        message.what = 0;
                        message.arg1 = i;
                        handler.sendMessage(message);
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }       
                }
            }

        }
    }

这是您可以录制音频以及播放音频的示例

You can store recorded file in following places
1) File directory of your app
2) External directory(SD card)
3) Network