Android 如果单击后退箭头关闭弹出菜单窗口，如何保持录音机运行

你能帮我做任何循环，直到我按stopRecording。如果我执行onBackPressed（）以返回第二个活动，记录器将自动停止。我希望它继续，直到我返回RecorderActivity并自己按下stop

我实现了在PopupMenuWindow中录制的音频，当我单击开始录制并按下后退箭头时，我通过调用

finish（）使用了此函数
onBackPressed（）
录音机停止录音

这是我使用的代码：

//Init View
        btnPlay = (Button)findViewById(R.id.btnPlay);
        btnStop = (Button) findViewById(R.id.btnStop);
        btnStartRecorder = (Button) findViewById(R.id.startRecord);
        btnStopRecorder = (Button) findViewById(R.id.stopRecord);
        //implementing the actions
        btnStartRecorder.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (checkPermissionFromDevice())
                {


                    pathSave = Environment.getExternalStorageDirectory()
                            .getAbsolutePath()+"/"
                            + UUID.randomUUID().toString()+"_audio_record.amr";
                    setupMediaRecorder();
                    try {
                        mediaRecorder.prepare();
                        mediaRecorder.start();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }

                    btnPlay.setEnabled(false);
                    btnStop.setEnabled(false);
                    btnStopRecorder.setEnabled(true);

                    Toast.makeText(RecorderActivity.this, "Recording...", Toast.LENGTH_SHORT).show();
                }

                else {
                    requestPermission();
                }
            }
        });

        btnStopRecorder.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                mediaRecorder.stop();
                mediaRecorder.release();
                btnStopRecorder.setEnabled(false);
                btnPlay.setEnabled(true);
                btnStartRecorder.setEnabled(true);
                btnStop.setEnabled(false);
                Toast.makeText(RecorderActivity.this, "Stop Record...", Toast.LENGTH_SHORT).show();
            }
        });

这是我的RecorderActivity.java，我在这里调用了MyService.java

public class RecorderActivity extends AppCompatActivity {


    Button btnStartRecorder, btnStopRecorder, btnPlay, btnStop;
    String pathSave = "";
    MediaRecorder mediaRecorder;
    MediaPlayer mediaPlayer;

    final int REQUEST_PERMISSION_CODE = 1000;


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


        final DisplayMetrics displayMetrics = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);

        int width = displayMetrics.widthPixels;
        int hight = displayMetrics.heightPixels;

        getWindow().setLayout((int)(width*.8), (int)(hight*.5));

        WindowManager.LayoutParams params = getWindow().getAttributes();
        params.gravity = Gravity.CENTER;
        params.x = 0;
        params.y = -20;

        getWindow().setAttributes(params);

        // Dismiss popUpMenu Window
        ImageButton backButton = (ImageButton) findViewById(R.id.back_arrow_record);
        backButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                finish();
            }
        });



        //Requesting Run-time permission
        if (!checkPermissionFromDevice())
            requestPermission();

        //Init View
        btnPlay = (Button)findViewById(R.id.btnPlay);
        btnStop = (Button) findViewById(R.id.btnStop);
        btnStartRecorder = (Button) findViewById(R.id.startRecord);
        btnStopRecorder = (Button) findViewById(R.id.stopRecord);
        //implementing the actions
        btnStartRecorder.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (checkPermissionFromDevice())
                {


                    Intent i = new Intent(getApplicationContext(), MyService.class);
                    i.setAction("C.ACTION_START_SERVICE");
                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                        startForegroundService(i);
                    }
                    else
                    {
                        startService(i);

                    }

                   

                    Toast.makeText(RecorderActivity.this, "Recording...", Toast.LENGTH_SHORT).show();
                }

                else {
                    requestPermission();
                }
            }
        });

        btnStopRecorder.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                MyService.mediaRecorder.stop();
                pathSave = MyService.pathSave;
                stopService(new Intent(RecorderActivity.this, MyService.class));
                btnStopRecorder.setEnabled(false);
                btnPlay.setEnabled(true);
                btnStartRecorder.setEnabled(true);
                btnStop.setEnabled(false);
                Toast.makeText(RecorderActivity.this, "Stop Record...", Toast.LENGTH_SHORT).show();
            }
        });

        btnPlay.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                btnStop.setEnabled(true);
                btnStopRecorder.setEnabled(false);
                btnStartRecorder.setEnabled(false);

                mediaPlayer = new MediaPlayer();
                try {
                    mediaPlayer.setDataSource(pathSave);
                    mediaPlayer.prepare();

                } catch (IOException e) {
                    e.printStackTrace();
                }

                mediaPlayer.start();
                Toast.makeText(RecorderActivity.this, "Playing...", Toast.LENGTH_SHORT).show();

            }
        });

        btnStop.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                btnStopRecorder.setEnabled(false);
                btnStartRecorder.setEnabled(true);
                btnStop.setEnabled(false);
                btnPlay.setEnabled(true);

                if (mediaPlayer != null){
                    mediaPlayer.stop();
                    mediaPlayer.release();
                    setupMediaRecorder();
                    Toast.makeText(RecorderActivity.this, "Stop Playing...", Toast.LENGTH_SHORT).show();
                }
            }
        });




    }

    private void setupMediaRecorder() {
        mediaRecorder = new MediaRecorder();
        mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
        mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.AMR_NB);
        mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
        mediaRecorder.setOutputFile(pathSave);
    }

    private void requestPermission() {
        ActivityCompat.requestPermissions(this, new String[]{
                Manifest.permission.WRITE_EXTERNAL_STORAGE,
                Manifest.permission.RECORD_AUDIO

        }, REQUEST_PERMISSION_CODE);
    }

    //Press Ctr+O


    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        switch (requestCode){
            case REQUEST_PERMISSION_CODE:
            {
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED)
                    Toast.makeText(this, "Permission Granted", Toast.LENGTH_SHORT).show();
                else {
                    Toast.makeText(this, "Permission Denied", Toast.LENGTH_SHORT).show();
                }
            }
            break;
        }
    }

    private boolean checkPermissionFromDevice() {
        int write_external_storage_result = ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE);
        int record_audio_result = ContextCompat.checkSelfPermission(this, Manifest.permission.RECORD_AUDIO);
        return write_external_storage_result == PackageManager.PERMISSION_GRANTED &&
                record_audio_result == PackageManager.PERMISSION_GRANTED;
    }

}

MyService.java代码实现

import android.app.Notification;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.graphics.Color;
import android.media.MediaRecorder;
import android.os.Build;
import android.os.Environment;
import android.os.IBinder;
import android.widget.Toast;


import androidx.annotation.Nullable;
import androidx.annotation.RequiresApi;
import androidx.core.app.NotificationCompat;

import java.io.IOException;
import java.util.UUID;

public class MyService extends Service {
    static MediaRecorder mediaRecorder;
    static final int NOTIFICATION_ID = 543;
    static String pathSave = "";

    public MyService() {
    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO: Return the communication channel to the service.
        throw new UnsupportedOperationException("Not yet implemented");
    }

    @Override
    public void onCreate() {
        super.onCreate();
        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.O)
            startMyOwnForeground();
        else
            startForeground(1, new Notification());

        pathSave = Environment.getExternalStorageDirectory()
                .getAbsolutePath() + "/"
                + UUID.randomUUID().toString() + "_audio_record.amr";
            setupMediaRecorder(); // add this line in your service 
        try {
            mediaRecorder.prepare();
            mediaRecorder.start();
            Toast.makeText(getApplicationContext(), "Recording...", Toast.LENGTH_SHORT).show();
        } catch (IOException e) {
            e.printStackTrace();
        }


    }

    @RequiresApi(Build.VERSION_CODES.O)
    private void startMyOwnForeground() {

        String NOTIFICATION_CHANNEL_ID = "example.permanence";
        String channelName = "Background Service";
        NotificationChannel chan = new NotificationChannel(NOTIFICATION_CHANNEL_ID, channelName, NotificationManager.IMPORTANCE_NONE);
        chan.setLightColor(Color.BLUE);
        chan.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);


        NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        assert manager != null;
        manager.createNotificationChannel(chan);

        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID);
        Notification notification = notificationBuilder.setOngoing(true)
                .setContentTitle("App is running in background")
                .setPriority(NotificationManager.IMPORTANCE_MIN)
                .setCategory(Notification.CATEGORY_SERVICE)

                .build();
        startForeground(2, notification);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {

        return START_STICKY;
        //return super.onStartCommand(intent, flags, startId);
    }


    @Override
    public void onDestroy() {
        super.onDestroy();
    }
//add this function in your service
private void setupMediaRecorder() {
        mediaRecorder = new MediaRecorder();
        mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
        mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.AMR_NB);
        mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
        mediaRecorder.setOutputFile(pathSave);
    }

}

按照您的指示，我得到了NPE

--------- beginning of crash
2020-09-12 12:25:02.371 24116-24116/com.igbogree.ogneneE/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.igbogree.ognene, PID: 24116
    java.lang.RuntimeException: Unable to create service com.igbogree.ognene.MyService: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.media.MediaRecorder.prepare()' on a null object reference
        at android.app.ActivityThread.handleCreateService(ActivityThread.java:3391)
        at android.app.ActivityThread.-wrap4(Unknown Source:0)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1712)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:164)
        at android.app.ActivityThread.main(ActivityThread.java:6549)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:888)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.media.MediaRecorder.prepare()' on a null object reference
        at com.igbogree.ognene.MyService.onCreate(MyService.java:50)
        at android.app.ActivityThread.handleCreateService(ActivityThread.java:3381)
        at android.app.ActivityThread.-wrap4(Unknown Source:0) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1712) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:164) 
        at android.app.ActivityThread.main(ActivityThread.java:6549) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:888) 

初始化清单中的服务，您必须在下面的开始按钮中调用该服务

Intent i = new Intent(this, AnotherService.class);
        i.setAction("C.ACTION_START_SERVICE");
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            startForegroundService(i);
        }
        else
        {
            startService(i);

        }

然后，您必须在服务中声明录音机，并按如下方式开始录音

public class AnotherService extends Service {
static MediaRecorder mediaRecorder;
static final int NOTIFICATION_ID = 543;
static String pathSave = "";
public AnotherService() {
}

@Override
public IBinder onBind(Intent intent) {
    // TODO: Return the communication channel to the service.
    throw new UnsupportedOperationException("Not yet implemented");
}

@Override
public void onCreate() {
    super.onCreate();
   if (Build.VERSION.SDK_INT > Build.VERSION_CODES.O)
        startMyOwnForeground();
    else
        startForeground(1, new Notification());
        
    pathSave = Environment.getExternalStorageDirectory()
                        .getAbsolutePath()+"/"
                        + UUID.randomUUID().toString()+"_audio_record.amr";
                setupMediaRecorder();
                try {
                    mediaRecorder.prepare();
                    mediaRecorder.start();
                    Toast.makeText(RecorderActivity.this, "Recording...", Toast.LENGTH_SHORT).show();
                } catch (IOException e) {
                    e.printStackTrace();
                }
    

   
}

@RequiresApi(Build.VERSION_CODES.O)
private void startMyOwnForeground() {

    String NOTIFICATION_CHANNEL_ID = "example.permanence";
    String channelName = "Background Service";
    NotificationChannel chan = new NotificationChannel(NOTIFICATION_CHANNEL_ID, channelName, NotificationManager.IMPORTANCE_NONE);
    chan.setLightColor(Color.BLUE);
    chan.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);


    NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
    assert manager != null;
    manager.createNotificationChannel(chan);

    NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID);
    Notification notification = notificationBuilder.setOngoing(true)
            .setContentTitle("App is running in background")
            .setPriority(NotificationManager.IMPORTANCE_MIN)
            .setCategory(Notification.CATEGORY_SERVICE)

            .build();
    startForeground(2, notification);
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {

    return START_STICKY;
    //return super.onStartCommand(intent, flags, startId);
}


@Override
public void onDestroy() {
    super.onDestroy();
}

如果您已经完成了服务，那么您必须在您想要停止的活动中更改停止按钮代码

AnotherService.mediaRecorder.stop();
pathSave = AnotherService.pathSave;
stopService(new Intent(YourActivity.this, AnotherService.class));

致以最诚挚的问候
初始化清单中的服务，您必须按下面的“开始”按钮调用该服务

Intent i = new Intent(this, AnotherService.class);
        i.setAction("C.ACTION_START_SERVICE");
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            startForegroundService(i);
        }
        else
        {
            startService(i);

        }

然后，您必须在服务中声明录音机，并按如下方式开始录音

public class AnotherService extends Service {
static MediaRecorder mediaRecorder;
static final int NOTIFICATION_ID = 543;
static String pathSave = "";
public AnotherService() {
}

@Override
public IBinder onBind(Intent intent) {
    // TODO: Return the communication channel to the service.
    throw new UnsupportedOperationException("Not yet implemented");
}

@Override
public void onCreate() {
    super.onCreate();
   if (Build.VERSION.SDK_INT > Build.VERSION_CODES.O)
        startMyOwnForeground();
    else
        startForeground(1, new Notification());
        
    pathSave = Environment.getExternalStorageDirectory()
                        .getAbsolutePath()+"/"
                        + UUID.randomUUID().toString()+"_audio_record.amr";
                setupMediaRecorder();
                try {
                    mediaRecorder.prepare();
                    mediaRecorder.start();
                    Toast.makeText(RecorderActivity.this, "Recording...", Toast.LENGTH_SHORT).show();
                } catch (IOException e) {
                    e.printStackTrace();
                }
    

   
}

@RequiresApi(Build.VERSION_CODES.O)
private void startMyOwnForeground() {

    String NOTIFICATION_CHANNEL_ID = "example.permanence";
    String channelName = "Background Service";
    NotificationChannel chan = new NotificationChannel(NOTIFICATION_CHANNEL_ID, channelName, NotificationManager.IMPORTANCE_NONE);
    chan.setLightColor(Color.BLUE);
    chan.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);


    NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
    assert manager != null;
    manager.createNotificationChannel(chan);

    NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID);
    Notification notification = notificationBuilder.setOngoing(true)
            .setContentTitle("App is running in background")
            .setPriority(NotificationManager.IMPORTANCE_MIN)
            .setCategory(Notification.CATEGORY_SERVICE)

            .build();
    startForeground(2, notification);
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {

    return START_STICKY;
    //return super.onStartCommand(intent, flags, startId);
}


@Override
public void onDestroy() {
    super.onDestroy();
}

如果您已经完成了服务，那么您必须在您想要停止的活动中更改停止按钮代码

AnotherService.mediaRecorder.stop();
pathSave = AnotherService.pathSave;
stopService(new Intent(YourActivity.this, AnotherService.class));

致以最诚挚的问候
我已经更新了关于我如何执行您指示的OP。当我测试时，我得到了Nul pointerException。请纠正我。把你的录音机放好；从您的活动到服务，您可以提交行以检查我已在OP上发布了完整代码。请检查并在您的答案中更正我。所以我会花时间去了解你是怎么做到的。感谢来到这里，因为梅可以离开承诺，这可以帮助你找到changingRafaqat，你很有学问！！你应该得到一瓶冰镇啤酒。非常感谢你！我欠你很多。上帝保佑你。我将尽我最大的努力在我的MediaPlayer上实现这项服务，它有13个播放按钮和1个停止按钮。我已经更新了关于我如何执行您的指令的OP。当我测试时，我得到了Nul pointerException。请纠正我。把你的录音机放好；从您的活动到服务，您可以提交行以检查我已在OP上发布了完整代码。请检查并在您的答案中更正我。所以我会花时间去了解你是怎么做到的。感谢来到这里，因为梅可以离开承诺，这可以帮助你找到changingRafaqat，你很有学问！！你应该得到一瓶冰镇啤酒。非常感谢你！我欠你很多。上帝保佑你。我会尽力在我的MediaPlayer上实现这项服务，它有13个播放按钮和1个停止按钮。