Android音乐播放器高级开发

获取手机音乐的信息

1. 先在布局文件中添加一个ListView

<ListView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:divider="@color/list_pressed"
    android:dividerHeight="1px"
    android:listSelector="@android:color/transparent"
    android:id="@+id/listview">

2. 在fragment中初始化这个ListView

private ListView listView;
  
  listView = (ListView) view.findViewById(R.id.listview);

3. 创建一个用于设置数据的adapter

public class AudioListAdapter extends CursorAdapter{

  public AudioListAdapter(Context context, Cursor c) {
    super(context, c);
  }

  //设置需要显示的布局文件
  @Override
  public View newView(Context context, Cursor cursor, ViewGroup parent) {
    return null;
  }
  
  //设置相关的数据的显示
  @Override
  public void bindView(View view, Context context, Cursor cursor) {
    
  }
  }

4. 优化adapter并为其设置数据的显示

4.1 创建一个viewHolder

class ViewHolder{
    //这里是用于显示相关歌曲的名称与艺术家名称的控件，
    TextView mTitleTextView,mArtistTextView;
    
    public ViewHolder(View view)
    {
      mTitleTextView = (TextView) view.findViewById(R.id.tv_title);
      mArtistTextView = (TextView) view.findViewById(R.id.tv_artist);
    }

4.2 创建一个方法用于获取上面的viewHolder

private ViewHolder getHolder(View view)
    {
      ViewHolder viewHolder = (ViewHolder) view.getTag();
      if(viewHolder==null)
      {
        viewHolder = new ViewHolder(view);
        view.setTag(viewHolder);
      }
      return viewHolder;
    }

4.3 在adapter中使用viewHolder

public class AudioListAdapter extends CursorAdapter
    {

      public AudioListAdapter(Context context, Cursor c) {
        super(context, c);
      }

      @Override
      public View newView(Context context, Cursor cursor, ViewGroup parent) 
      {
      //设置显示音乐信息的列表内容
        return View.inflate(context, R.layout.adapter_audio_list, null);
      }
      ViewHolder holder;
      @Override
      public void bindView(View view, Context context, Cursor cursor) 
      {
        holder = getHolder(view);
      
        //这里是通过对象保存数据的方式将cursor中的数据取出并设置相关显示
        AudioItem audioItem = AudioItem.fromCursor(cursor);
        holder.mTitleTextView.setText(StringUtil.formatAudioName(audioItem.getTitle()));
        holder.mArtistTextView.setText(audioItem.getArtist());
      }
    }

4.4 这里是使用的对象保存数据的方法

public class AudioItem implements Serializable
    {
    private String title;
    private String artist;
    private String path;
    private long duration;
    
    //将cursor的数据封装于对象
    public static AudioItem fromCursor(Cursor cursor){
      AudioItem audioItem = new AudioItem();
      audioItem.setArtist(cursor.getString(cursor.getColumnIndex(Media.ARTIST)));
      audioItem.setDuration(cursor.getLong(cursor.getColumnIndex(Media.DURATION)));
      audioItem.setPath(cursor.getString(cursor.getColumnIndex(Media.DATA)));
      audioItem.setTitle(cursor.getString(cursor.getColumnIndex(Media.DISPLAY_NAME)));
      return audioItem;
    }
    
    public String getTitle() {
      return title;
    }
    public void setTitle(String title) {
      this.title = title;
    }
    public String getArtist() {
      return artist;
    }
    public void setArtist(String artist) {
      this.artist = artist;
    }
    public String getPath() {
      return path;
    }
    public void setPath(String path) {
      this.path = path;
    }
    public long getDuration() {
      return duration;
    }
    public void setDuration(long duration) {
      this.duration = duration;
    }
    }

5 在fragment中初使化adapter并使用这个adapter

private AudioListAdapter mAudioAdapter;
  
  mAudioAdapter = new AudioListAdapter(getActivity(), null);

6 将adapter设置给ListView

listView.setAdapter(adapter);

7 查询数据并将数据传输给mAudioAdapter

private SimpleQueryHandler queryHandler;
  
    queryHandler = new SimpleQueryHandler(getActivity().getContentResolver());
    //查询的音乐相关的信息
    String[] projection = {Media._ID,Media.DISPLAY_NAME,Media.ARTIST,Media.DATA,Media.DURATION};
    //数据查询
    queryHandler.startQuery(0, adapter, Media.EXTERNAL_CONTENT_URI, projection, null, null, null);

8 使用到的相关查询辅助类

public class SimpleQueryHandler  extends AsyncQueryHandler{

  public SimpleQueryHandler(ContentResolver cr) {
    super(cr);
  }
  @Override
  protected void onQueryComplete(int token, Object cookie, Cursor cursor) {
    super.onQueryComplete(token, cookie, cursor);
    
    if(cookie!=null && cookie instanceof CursorAdapter){
      CursorAdapter adapter = (CursorAdapter) cookie;
      adapter.changeCursor(cursor);//相当于notify
    }
  }
  }

走到这里，我们就可以将手机中的音乐相关信息显示加载出来了

2 播放音乐的操作

9 创建用于播放音乐的显示页面（这里使用一个activity来显示）

public class AudioPlayerActivity extends  Activity{


}

在这里设置自定的播放音乐的显示页面

10 在AudioPlayerActivity的onCreate方法中获取传递的数据

//当前点击要播放的位置
      int currentPosition = getIntent().getExtras().getInt("currentPosition");
      
//所有音乐信息的集合
      ArrayList<AudioItem> audioList = (ArrayList<AudioItem>) getIntent().getExtras().getSerializable("audioList");

11 这里使用的是后台可以进行音乐播放，那么就需要使用到与服务的交互

创建用于播放音乐的服务并进行清单文件中的注册

public class AudioPlayService extends Service{
  
    private AudioServiceBinder audioServiceBinder;
    @Override
    public IBinder onBind(Intent intent) {
        return audioServiceBinder;
      }
    }
    @Override
    public void onCreate() {
      super.onCreate();
      audioServiceBinder = new AudioServiceBinder();
    
    }
    
    //数据相关的绑定操作
    public class AudioServiceBinder extends Binder{
    }
  }

12 在播放音乐的activity中开启服务

AudioPlayerActivity的onCreate方法中

Intent intent = new Intent(this,AudioPlayService.class);
    Bundle bundle = new Bundle();
    
    //传输的数据
      int currentPosition = getIntent().getExtras().getInt("currentPosition");
      ArrayList<AudioItem> audioList = (ArrayList<AudioItem>) getIntent().getExtras().getSerializable("audioList");
    //数据封装
      bundle.putInt("currentPosition", currentPosition);
      bundle.putSerializable("audioList", audioList);
      intent.putExtras(bundle);
    //服务绑定
    
    serviceConnection = new AudioServiceConnection();
    
    bindService(intent, serviceConnection, Service.BIND_AUTO_CREATE);
    startService(intent);//为了给service传递数据

使用到对象 serviceConnection,类似一个中间人对象，是实现ServiceConnection接口的

class AudioServiceConnection implements ServiceConnection{
    //当服务连接的时候会调用这个方法
    @Override
    public void onServiceConnected(ComponentName name, IBinder service) {
      
    }
    //当服务断开时候会调用这个方法
    @Override
    public void onServiceDisconnected(ComponentName name) {
      
    }
  }

13 activity 与 service方法的交互

在activity中 通过 serviceConnection 来获取 服务 AudioPlayService 中的AudioServiceBinder

这样我们就可以通过AudioServiceBinder这个对象来进行activity与service中方法的交互

private AudioServiceBinder audioServiceBinder;
  
  class AudioServiceConnection implements ServiceConnection{
    //当服务连接的时候会调用这个方法，那么可以在这个方法中获取binder的对象（通过它来操作服务中的相关方法）
    @Override
    public void onServiceConnected(ComponentName name, IBinder service) {
      audioServiceBinder = (AudioServiceBinder) service;
    }
    //当服务断开时候会调用这个方法
    @Override
    public void onServiceDisconnected(ComponentName name) {
      
    }
  }

14 在service中进行播放音乐的操作

首先获取传递的数据 
  复写service的方法 onStartCommand  来获取传递的数据 
  private int currentPosition;
  private ArrayList<AudioItem> audioList;
  private AudioServiceBinder audioServiceBinder ;
  
  @Override
  public void onCreate() {
    super.onCreate();
    audioServiceBinder = new AudioServiceBinder();
    
  }
  
  @Override
  public int onStartCommand(Intent intent, int flags, int startId) {
  
  //获取数据
      currentPosition = intent.getExtras().getInt("currentPosition");
      audioList = (ArrayList<AudioItem>) intent.getExtras().getSerializable("audioList");
  //设置音乐播放
      audioServiceBinder.playAudio();
    
    return START_STICKY;//如果服务被杀死，会自动重启
  }
  
  在AudioServiceBinder 中设置与播放音乐相关的操作逻辑 
  设置播放音乐的操作方法 
    public class AudioServiceBinder extends Binder{
      /**
       * 播放音乐
       */
      public void playAudio(){
      //判断一下是否有音乐资源
        if(audioList==null || audioList.size()==0)return;
        if(mediaPlayer!=null){
          mediaPlayer.release();
          mediaPlayer = null;
        }
        
        AudioItem audioItem = audioList.get(currentPosition);
      //创建mediaPlayer对象
        mediaPlayer = new MediaPlayer();
      //设置相关的监听
        mediaPlayer.setOnPreparedListener(mOnPreparedListener);
        mediaPlayer.setOnCompletionListener(mOnCompletionListener);
      //设置数据源
        try {
          mediaPlayer.setDataSource(audioItem.getPath());
          mediaPlayer.prepareAsync();
        } catch (IllegalArgumentException e) {
          e.printStackTrace();
        } catch (SecurityException e) {
          e.printStackTrace();
        } catch (IllegalStateException e) {
          e.printStackTrace();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
      //创建相关的加载播放监听 并设置音乐的播放
      
      private OnPreparedListener mOnPreparedListener = new OnPreparedListener() {
        @Override
        public void onPrepared(MediaPlayer mp) {
          mediaPlayer.start();
    
        }
      };
      
      private OnCompletionListener mOnCompletionListener = new OnCompletionListener() {
        @Override
        public void onCompletion(MediaPlayer mp) {
          
        }
      };
    }

15 在服务中通过发送广播通知Activity中更新页面显示数据

定义我们用到的广播接收者

class AudioServiceReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
      
    }
  }

在activity的OnCreate方法中进行注册

/**
   * 注册AudioService中的广播接受者
   */
  private void registerAudioServiceReceiver() {
    receiver = new AudioServiceReceiver();
    IntentFilter filter = new IntentFilter(AudioPlayService.ACTION_NOTIFY_PREPARED);//参数是广播接收的标识
    //filter.addAction(AudioPlayService.ACTION_COMPLATION); 这里可以添加多个活动
    registerReceiver(receiver, filter);
  }

在服务中，当音乐开始进行播放的时候，发送广播，并将音乐的信息发给activity中

private void notifyPrepared(){
    Intent intent = new Intent(ACTION_NOTIFY_PREPARED);
    intent.putExtra("audioItem", audioList.get(currentPosition));//这里面就是携带的数据
    sendBroadcast(intent);
  }

当广播发送后，我们在对应的广播接收者中进行消息的接收

class AudioServiceReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
      if (AudioPlayService.ACTION_NOTIFY_PREPARED.equarrayLists(intent.getAction())) {
        AudioItem audioItem = (AudioItem) intent.getSeriarrayListizableExtra("audioItem");

      } else if (AudioPlayService.ACTION_COMPLATION.equarrayLists(intent.getAction())) {
      }
    }
  }