Exoplayer音频未在后台服务中播放

Question

因此，我开发了一个使用exoplayer库来流音乐URL的android应用程序。但是，在创建后台服务以在后台启用音乐流后，它不起作用，但是当我尝试将其作为后台（MainActivity）时，相同的代码也可以工作。

Android清单

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
package="com.sparrowpaul.musicservice">

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

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme"
    tools:ignore="GoogleAppIndexingWarning">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <service android:name=".BackgroundService"/>

</application>

MainActivity.Java

package com.sparrowpaul.musicservice;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;

公共类MainActivity扩展了AppCompatActivity {

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

    Intent intent = new Intent(MainActivity.this, BackgroundService.class);
    startService(intent);



}

}

BackgroundService.java

公共类BackgroundService扩展Service实现ExoPlayer.EventListener {

private Handler mainHandler;
private RenderersFactory renderersFactory;
private BandwidthMeter bandwidthMeter;
private LoadControl loadControl;
private DataSource.Factory dataSourceFactory;
private ExtractorsFactory extractorsFactory;
private MediaSource mediaSource;
private TrackSelection.Factory trackSelectionFactory;
private SimpleExoPlayer player;
private final String streamUrl = "http://bbcwssc.ic.llnwd.net/stream/bbcwssc_mp1_ws-einws";
private TrackSelector trackSelector;

@Override
public void onCreate() {
    super.onCreate();
    startPlayer();
}

@Override
public IBinder onBind(Intent intent) {
    return null;
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    startPlayer();
    return START_STICKY;
}

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

public void startPlayer(){

    renderersFactory = new DefaultRenderersFactory(getApplicationContext());
    bandwidthMeter = new DefaultBandwidthMeter();
    trackSelectionFactory = new AdaptiveTrackSelection.Factory(bandwidthMeter);
    trackSelector = new DefaultTrackSelector(trackSelectionFactory);
    loadControl = new DefaultLoadControl();

    player = ExoPlayerFactory.newSimpleInstance(this, renderersFactory, trackSelector, loadControl);

    player.addListener(this);

    dataSourceFactory = new DefaultDataSourceFactory(getApplicationContext(), "ExoplayerDemo");
    extractorsFactory = new DefaultExtractorsFactory();
    mainHandler = new Handler();
    mediaSource = new ExtractorMediaSource(Uri.parse(streamUrl),
            dataSourceFactory,
            extractorsFactory,
            mainHandler,
            null);

    player.prepare(mediaSource);
}

}

Answer 1

您需要以foreground service的身份启动服务并为其提供通知。 ExoPlayer的ui模块带有PlayerNotificationManager which helps you with the notification。

大约需要start your service as as a foreground service in your activity。然后，一旦您的服务创建了通知，您就需要调用startForeground（notificationId，notification）。如果您不作为前台服务启动，则系统将在短时间内停止您的服务。另请参见：https://developer.android.com/guide/components/services#Foreground

下面的示例给出了有关如何使用ExoPlayers通知管理器的想法。

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
  if (player == null) {
    startPlayer();
    playerNotificationManager = new PlayerNotificationManager(
        this, CHANNEL_ID, NOTIFICATION_ID,
        createMediaDescriptionAdapter(),
        new PlayerNotificationManager.NotificationListener() {
          @Override
          public void onNotificationPosted(int notificationId, Notification notification, boolean ongoing) {
            startForeground(notificationId, notification);
          }
          @Override
          public void onNotificationCancelled(int notificationId, boolean dismissedByUser) {
            if (dismissedByUser) {
              // Do what the app wants to do when dismissed by the user,
              // like calling stopForeground(true); or stopSelf();
            }
          }
    });
    playerNotificationManager.setPlayer(player);
  }
  return START_STICKY;
}