在服务中使用 MediaPlayer Class...？
Using MediaPlayer in a Service Class...?
我正在制作一个应用程序，目前正在为它添加背景音乐。我见过很多方法可以做到这一点，我选择使用服务来实现。
但是，当我调用该服务时，我的问题就来了，因为我什么也没听到，音乐没有播放！我已经与另一个示例进行了比较，并尝试了几乎所有的方法，但没有任何变化......相反，我正在使用 IntentService 播放音乐（至少有一些东西），但它不是很好，因为例如，当我按下主页按钮时，音乐会继续播放...
服务代码Class如下：
package edu.ub.pis2016.darmas.entrega1;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.IBinder;
import android.widget.Toast;
public class Service_1 extends Service {
MediaPlayer player;
public IBinder onBind(Intent arg0) {
return null;
}
@Override
public void onCreate(){
super.onCreate();
player = MediaPlayer.create(this, R.raw.calm);
player.setLooping(true); // Set looping
player.setVolume(100,100);
}
@Override
public int onStartCommand(Intent intent, int flags, int startId){
player.start();
return 1;
}
@Override
public void onDestroy(){
player.stop();
player.release();
player = null;
}
public void onStop(){
player.stop();
}
public void onPause(){
}
}
然后我从我的一项活动中调用该服务，方法是：
Intent intent = new Intent(this, Service_1.class);
startService(intent);
但是没用...
相反，这是我的 IntentService class:
代码
package edu.ub.pis2016.darmas.entrega1;
import android.app.IntentService;
import android.content.Context;
import android.content.Intent;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.IBinder;
import android.view.KeyEvent;
import android.widget.Toast;
/*
* Service_music Class which extends from IntentService class. We do this due to with this latter,
* there's no need to implement a thread thanks to it creates by default (a worker thread),
* which runs in the background. Also, this class implements from Audiomanager, in order to
* control the different situations in where the music can be found through the phone.
*
*/
public class Service_music extends IntentService implements AudioManager.OnAudioFocusChangeListener {
MediaPlayer mp;
AudioManager audioManager;
boolean end = false;
/*
* ------------------------------------------------
* - Class Itself Methods -
* ------------------------------------------------
*/
// Constructor class, required! We create here our worker thread
public Service_music() {
super("Service_music_thread");
}
public IBinder onBind(Intent arg0) {
return null;
}
@Override
protected void onHandleIntent(Intent intent) {
lets_play_music();
while (end != true){}
}
@Override
public void onDestroy(){
super.onDestroy(); // It's mandatory to call the super() methods when extending from IntentService
if (this.mp != null) releaseMediaPlayer();
}
/*
* ------------------------------------------------
* - Initialize Methods -
* ------------------------------------------------
*/
// Method to initialize the media player
private void initializeMediaPlayer(){
//this.mp = MediaPlayer.create(this, R.raw.calm);
this.mp = MediaPlayer.create(this, R.raw.barefootandbruisdjamestownstory);
this.mp.setLooping(true);
this.mp.start();
}
private void initializeAudioManager(){
this.audioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
int result = audioManager.requestAudioFocus(this, AudioManager.STREAM_MUSIC,
AudioManager.AUDIOFOCUS_GAIN);
if (result != AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
// could not get audio focus.
Toast.makeText(getApplicationContext(), "Ha habido un error al iniciar la musica :(", Toast.LENGTH_SHORT).show();
}
}
/*
* ------------------------------------------------
* - Auxiliar Methods -
* ------------------------------------------------
*/
// This method will carry the task of playing the music, but notice this is only for local media!
private void lets_play_music(){
initializeAudioManager();
initializeMediaPlayer();
//initializeAudioManager();
//this.mp.start();
}
// Method to release all resources taken by the mp object
private void releaseMediaPlayer(){
this.mp.stop();
this.mp.release();
this.mp = null;
}
/*
* ------------------------------------------------
* - Audio Manager Methods -
* ------------------------------------------------
*/
public void onAudioFocusChange(int focusChange) {
// Do something based on focus change...
switch (focusChange){
// Case if we have gained the focus to play!
case AudioManager.AUDIOFOCUS_GAIN:
if (this.mp == null) initializeMediaPlayer(); // If we had to release the mp by any reason, we re-initialize it!
else if(!this.mp.isPlaying()) {
this.mp.setLooping(true); // In theory, it should play looping through infinitely
this.mp.start(); // If it's not currently playing, starts!
}
this.mp.setVolume(1.0f, 1.0f); // We set the volume!
break;
// Case if we have completely (or almost) lost the focus
case AudioManager.AUDIOFOCUS_LOSS:
if (this.mp.isPlaying()) this.mp.stop(); // If it's currently playing, we have to stop it first
end = true;
releaseMediaPlayer(); // We release the resources
break;
// Case if we have lost the focus for a short period of time
case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT:
if (this.mp.isPlaying()) this.mp.pause(); // If it's currently playing, we just pause it!
break;
// Case if we have lost the focus but for a tiny piece of time, so we're allowed to continue performing the music but in a quiet state!
case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK:
if (this.mp.isPlaying()) this.mp.setVolume(0.3f, 0.3f); // If it's currently playing, we just set the volume to a quiet level!
break;
}
}
}
后者有效，但 'AudioManager' 无效，当我按下 'home button' 时，音乐继续播放...
如果有人可以帮助我，或者告诉我错误在哪里，或者我做错了什么，来解决这个问题，我将非常感激，因为我对此很生气...
两个猜测（由于缺少完整代码）：
您的清单不包含该服务，因此它没有收到意图
R.raw.value 不存在
我正在制作一个应用程序，目前正在为它添加背景音乐。我见过很多方法可以做到这一点，我选择使用服务来实现。 但是，当我调用该服务时，我的问题就来了，因为我什么也没听到，音乐没有播放！我已经与另一个示例进行了比较，并尝试了几乎所有的方法，但没有任何变化......相反，我正在使用 IntentService 播放音乐（至少有一些东西），但它不是很好，因为例如，当我按下主页按钮时，音乐会继续播放...
服务代码Class如下：
package edu.ub.pis2016.darmas.entrega1;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.IBinder;
import android.widget.Toast;
public class Service_1 extends Service {
MediaPlayer player;
public IBinder onBind(Intent arg0) {
return null;
}
@Override
public void onCreate(){
super.onCreate();
player = MediaPlayer.create(this, R.raw.calm);
player.setLooping(true); // Set looping
player.setVolume(100,100);
}
@Override
public int onStartCommand(Intent intent, int flags, int startId){
player.start();
return 1;
}
@Override
public void onDestroy(){
player.stop();
player.release();
player = null;
}
public void onStop(){
player.stop();
}
public void onPause(){
}
}
然后我从我的一项活动中调用该服务，方法是：
Intent intent = new Intent(this, Service_1.class);
startService(intent);
但是没用... 相反，这是我的 IntentService class:
代码 package edu.ub.pis2016.darmas.entrega1;
import android.app.IntentService;
import android.content.Context;
import android.content.Intent;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.IBinder;
import android.view.KeyEvent;
import android.widget.Toast;
/*
* Service_music Class which extends from IntentService class. We do this due to with this latter,
* there's no need to implement a thread thanks to it creates by default (a worker thread),
* which runs in the background. Also, this class implements from Audiomanager, in order to
* control the different situations in where the music can be found through the phone.
*
*/
public class Service_music extends IntentService implements AudioManager.OnAudioFocusChangeListener {
MediaPlayer mp;
AudioManager audioManager;
boolean end = false;
/*
* ------------------------------------------------
* - Class Itself Methods -
* ------------------------------------------------
*/
// Constructor class, required! We create here our worker thread
public Service_music() {
super("Service_music_thread");
}
public IBinder onBind(Intent arg0) {
return null;
}
@Override
protected void onHandleIntent(Intent intent) {
lets_play_music();
while (end != true){}
}
@Override
public void onDestroy(){
super.onDestroy(); // It's mandatory to call the super() methods when extending from IntentService
if (this.mp != null) releaseMediaPlayer();
}
/*
* ------------------------------------------------
* - Initialize Methods -
* ------------------------------------------------
*/
// Method to initialize the media player
private void initializeMediaPlayer(){
//this.mp = MediaPlayer.create(this, R.raw.calm);
this.mp = MediaPlayer.create(this, R.raw.barefootandbruisdjamestownstory);
this.mp.setLooping(true);
this.mp.start();
}
private void initializeAudioManager(){
this.audioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
int result = audioManager.requestAudioFocus(this, AudioManager.STREAM_MUSIC,
AudioManager.AUDIOFOCUS_GAIN);
if (result != AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
// could not get audio focus.
Toast.makeText(getApplicationContext(), "Ha habido un error al iniciar la musica :(", Toast.LENGTH_SHORT).show();
}
}
/*
* ------------------------------------------------
* - Auxiliar Methods -
* ------------------------------------------------
*/
// This method will carry the task of playing the music, but notice this is only for local media!
private void lets_play_music(){
initializeAudioManager();
initializeMediaPlayer();
//initializeAudioManager();
//this.mp.start();
}
// Method to release all resources taken by the mp object
private void releaseMediaPlayer(){
this.mp.stop();
this.mp.release();
this.mp = null;
}
/*
* ------------------------------------------------
* - Audio Manager Methods -
* ------------------------------------------------
*/
public void onAudioFocusChange(int focusChange) {
// Do something based on focus change...
switch (focusChange){
// Case if we have gained the focus to play!
case AudioManager.AUDIOFOCUS_GAIN:
if (this.mp == null) initializeMediaPlayer(); // If we had to release the mp by any reason, we re-initialize it!
else if(!this.mp.isPlaying()) {
this.mp.setLooping(true); // In theory, it should play looping through infinitely
this.mp.start(); // If it's not currently playing, starts!
}
this.mp.setVolume(1.0f, 1.0f); // We set the volume!
break;
// Case if we have completely (or almost) lost the focus
case AudioManager.AUDIOFOCUS_LOSS:
if (this.mp.isPlaying()) this.mp.stop(); // If it's currently playing, we have to stop it first
end = true;
releaseMediaPlayer(); // We release the resources
break;
// Case if we have lost the focus for a short period of time
case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT:
if (this.mp.isPlaying()) this.mp.pause(); // If it's currently playing, we just pause it!
break;
// Case if we have lost the focus but for a tiny piece of time, so we're allowed to continue performing the music but in a quiet state!
case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK:
if (this.mp.isPlaying()) this.mp.setVolume(0.3f, 0.3f); // If it's currently playing, we just set the volume to a quiet level!
break;
}
}
}
后者有效，但 'AudioManager' 无效，当我按下 'home button' 时，音乐继续播放...
如果有人可以帮助我，或者告诉我错误在哪里，或者我做错了什么，来解决这个问题，我将非常感激，因为我对此很生气...
两个猜测（由于缺少完整代码）：
您的清单不包含该服务，因此它没有收到意图 R.raw.value 不存在