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出一些问题（它正在抛出） NullPointerException）。任何人都可以提出可能存在的问题吗？
答案 0 :(得分：1)
您无法在Asset文件夹中保存文件。资产文件夹是只读的，而不是它，您必须将其保存在设备的内部或外部存储中
下面有一个记录媒体文件的核心。
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