如何解决如果单击“开始”之前先单击“停止记录器”按钮,则单击时会引发null异常
我已经使用此代码一段时间了,然后才发现在单击startButton之前,第一次单击Stop StopButton会引发null异常。 我将录音机放在PopupMenuWindow中。因此,如果我打开该应用程序并决定先单击stopRecording,它将引发异常。
但是,如果我先单击startRecording,然后单击stopRecorder,一切都会顺利进行。
这是我的 RecorderActivity.java
//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);
}
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) {
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();
}
});
这是记录器的 MyService.java
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(),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);
}
}
解决方法
单击停止按钮时,您的MyService尚未运行。因此,它正在试图阻止不存在的事物。
选项1:禁用停止按钮,直到服务启动为止。
选项2:在停止按钮onclick方法中检查服务是否正在运行。如果正在运行,请停止它,如果不执行任何操作。这是另一个答案,显示了如何查看服务是否正在运行。 How to check if a service is running on Android?