用mediarecoder 写一个录音demo

好的，下面是一个使用MediaRecorder录制音频的简单Demo：

1. 在AndroidManifest.xml中添加录音权限：

<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

2. 在布局文件中添加一个按钮，用于开始录制音频：

<Button
    android:id="@+id/start_recording_button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Start Recording" />

3. 在Activity中添加如下代码：

private MediaRecorder mediaRecorder;
private String audioFilePath;
private Button startRecordingButton;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    startRecordingButton = findViewById(R.id.start_recording_button);
    startRecordingButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            startRecording();
        }
    });
}

private void startRecording() {
    // 创建音频文件
    File audioFile = null;
    try {
        audioFile = createAudioFile();
    } catch (IOException e) {
        e.printStackTrace();
    }

    // 初始化MediaRecorder
    mediaRecorder = new MediaRecorder();
    mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
    mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
    mediaRecorder.setOutputFile(audioFile.getAbsolutePath());
    mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);

    // 开始录制音频
    try {
        mediaRecorder.prepare();
        mediaRecorder.start();
        startRecordingButton.setText("Stop Recording");
    } catch (IOException e) {
        e.printStackTrace();
    }
}

private void stopRecording() {
    // 停止录制音频
    mediaRecorder.stop();
    mediaRecorder.release();
    mediaRecorder = null;
    startRecordingButton.setText("Start Recording");
}

private File createAudioFile() throws IOException {
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    String audioFileName = "AUDIO_" + timeStamp + "_";
    File storageDir = getExternalFilesDir(Environment.DIRECTORY_MUSIC);
    File audioFile = File.createTempFile(audioFileName, ".3gp", storageDir);
    audioFilePath = audioFile.getAbsolutePath();
    return audioFile;
}

@Override
protected void onStop() {
    super.onStop();
    if (mediaRecorder != null) {
        mediaRecorder.release();
        mediaRecorder = null;
    }
}

这个Demo实现了一个简单的录音功能，点击按钮即可开始录制音频，再次点击按钮即可停止录制。录制完成后，音频文件会保存在应用的私有目录中，可以通过audioFilePath获取到音频文件的路径。