如何在Android上使用麦克风

import android.media.AudioFormat;
import android.media.AudioRecord;
import android.media.MediaRecorder;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.widget.Button;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

import java.io.FileOutputStream;
import java.io.IOException;

public class MainActivity extends AppCompatActivity {

    private static final int SAMPLE_RATE = 44100;
    private static final int CHANNEL_CONFIG = AudioFormat.CHANNEL_IN_MONO;
    private static final int AUDIO_FORMAT = AudioFormat.ENCODING_PCM_16BIT;
    private static final int BUFFER_SIZE = AudioRecord.getMinBufferSize(SAMPLE_RATE, CHANNEL_CONFIG, AUDIO_FORMAT);

    private AudioRecord audioRecord;
    private Button startButton;
    private Button stopButton;

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

        startButton = findViewById(R.id.start_button);
        stopButton = findViewById(R.id.stop_button);

        startButton.setOnClickListener(v -> startRecording());
        stopButton.setOnClickListener(v -> stopRecording());

        audioRecord = new AudioRecord.Builder()
                .setAudioSource(MediaRecorder.AudioSource.MIC)
                .setAudioFormat(new AudioFormat.Builder()
                        .setEncoding(AUDIO_FORMAT)
                        .setSampleRate(SAMPLE_RATE)
                        .setChannelMask(CHANNEL_CONFIG)
                        .build())
                .setBufferSizeInBytes(BUFFER_SIZE)
                .build();

        if (audioRecord.getState() != AudioRecord.STATE_INITIALIZED) {
            Toast.makeText(this, "AudioRecord initialization failed", Toast.LENGTH_SHORT).show();
            finish();
        }
    }

    private void startRecording() {
        audioRecord.startRecording();
        Toast.makeText(this, "Recording started", Toast.LENGTH_SHORT).show();

        new Thread(() -> {
            FileOutputStream fos = null;
            try {
                fos = new FileOutputStream(Environment.getExternalStorageDirectory() + "/record.pcm");
                byte[] buffer = new byte[BUFFER_SIZE];
                int bytesRead;
                while (audioRecord.getRecordingState() == AudioRecord.RECORDSTATE_RECORDING) {
                    bytesRead = audioRecord.read(buffer, 0, BUFFER_SIZE);
                    fos.write(buffer, 0, bytesRead);
                }
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                if (fos != null) {
                    try {
                        fos.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        }).start();
    }

    private void stopRecording() {
        audioRecord.stop();
        Toast.makeText(this, "Recording stopped", Toast.LENGTH_SHORT).show();
    }
}