Android- ListView 、服务媒体播放器和 boolean 标志

Question

我目前有一个 listview，当您单击一个项目时，它会运行一个带有 mediaplayer 的服务。如果我单击 listview 中的另一个项目，正在运行的 service 应该停止并运行新的 service。我正在使用一个 boolean isRunning 设置为 false，当服务创建时它返回 true。然后在 listview 中，我在 if 语句中调用该标志。但是，它并不完全有效。我想我可能做错了。有什么想法吗？

我的描述方式听起来可能令人困惑，所以这是我的 listview 和 service 的代码。我只是在案例 3 上测试这个(所以我按下这个项目来启动服务，然后点击案例 2 看它是否会停止它)。

ListView 类:

public class PlaylistActivity extends ListActivity{

    private static final String TAG = PlaylistActivity.class.getSimpleName();

    // Data to put in the ListAdapter
    private String[] sdrPlaylistNames = new String[] {
            "Best of June 2011", "Best of May 2011", "Dubstep",
            "House", "Other"};

    private ListAdapter sdrListAdapter;
    Intent playbackServiceIntentBOJ, playbackServiceIntentBOM, playbackServiceIntentDUB;



    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.playlists_layout);
        //fill the screen with the list adapter
        playlistFillData();

        playbackServiceIntentDUB = new Intent(this, DUBAudioService.class);
        Log.d(TAG, "Made DUB Service Intent");
    }

    public void playlistFillData() {
        //create and set up the Array adapter for the list view
        ArrayAdapter sdrListAdapter = new ArrayAdapter(this, R.layout.list_item, sdrPlaylistNames);
        setListAdapter(sdrListAdapter);
    }

    //set up the on list item Click 
    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        super.onListItemClick(l, v, position, id);
        //create a switch so that each list item is a different playlist
        switch(position){
        case 0:
            Intent BOJintent = new Intent(this, BOJAudioActivity.class);
            // Create the view using PlaylistGroup's LocalActivityManager
            View view = PlaylistGroup.group.getLocalActivityManager()
            .startActivity("show_city", BOJintent
            .addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP))
            .getDecorView();

            // Again, replace the view
            PlaylistGroup.group.replaceView(view);

         //   playbackServiceIntentBOJ = new Intent(this, BOJAudioService.class);
                Log.d(TAG, "Made BOJ Intent");
        //  startService(playbackServiceIntentBOJ);
                Log.d(TAG, "started BOJ Service");

            break;
        case 1:
            Intent BOMintent = new Intent(this, BOMAudioActivity.class);
            // Create the view using PlaylistGroup's LocalActivityManager
            View view2 = PlaylistGroup.group.getLocalActivityManager()
            .startActivity("show_city", BOMintent
            .addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP))
            .getDecorView();

            // Again, replace the view
           PlaylistGroup.group.replaceView(view2);
                Log.d(TAG, "Replace view");

                //getApplicationContext().stopService(playbackServiceIntentBOJ);

            //playbackServiceIntentBOM = new Intent(this, BOJAudioService.class);
                Log.d(TAG, "Made BOM Service Intent");
        //  startService(playbackServiceIntentBOM);
                Log.d(TAG, "started BOM Service");

                if(DUBAudioActivity.isRunningDUB = true){
                    stopService(playbackServiceIntentDUB);
                    Log.d(TAG, "stop service isRunningDUB");
                }
//
            break;
        case 2:

            Intent DUBIntent = new Intent (this, DUBAudioActivity.class);
            View view3 = PlaylistGroup.group.getLocalActivityManager()
                        .startActivity("show_city", DUBIntent
                                .addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP))
                                .getDecorView();
            PlaylistGroup.group.replaceView(view3);
                Log.d(TAG, "Replace view");

            startService(playbackServiceIntentDUB);
                Log.d(TAG, "started DUB service");

            break;

        }


    }


}

服务等级:

public class DUBAudioService extends Service implements OnPreparedListener, OnCompletionListener{

Toast loadingMessage;

private static final String TAG = DUBAudioService.class.getSimpleName();

    public static boolean isRunningDUB = false;

    //to keep track of the playlist item
    Vector<PlaylistFile> playlistItems;

    MediaPlayer mediaPlayer;

    String baseURL = "";

    //keep track of which item from the vector we are on
    int currentPlaylistltemNumber = 0;

    public class DUBBackgroundAudioServiceBinder extends Binder {
        DUBAudioService getService() {
        return DUBAudioService.this;
        }
    }

    private final IBinder basBinderDUB = new DUBBackgroundAudioServiceBinder();



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

    @Override
    public void onCreate() {
        Log.v("PLAYERSERVICE", "onCreate");
        mediaPlayer = new MediaPlayer();
        new MusicAsync().execute();
            Log.d(TAG, "execute'd async");
        mediaPlayer.setOnPreparedListener(this);
            Log.d(TAG, "set on prepared listener");
        mediaPlayer.setOnCompletionListener(this);
            Log.d(TAG, "set on completion listener");

            isRunningDUB = true;
            Log.d(TAG, "isRunningRUB = true");
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        //if (!mediaPlayer.isPlaying()) {
        //  mediaPlayer.start();
        //}
        return START_STICKY;
    }


    class MusicAsync extends AsyncTask<Void,Void,Void>{
        @Override
        protected void onPreExecute(){
        }
        @Override
        protected Void doInBackground(Void... arg0) {
            // TODO Auto-generated method stub

            //create empty vector 
            playlistItems = new Vector<PlaylistFile>();

            //HTTP client library
            HttpClient httpClient = new DefaultHttpClient();
            HttpGet getRequest = new HttpGet ("http://dl.dropbox.com/u/24535120/m3u%20playlist/DubstepPlaylist.m3u"); //i think you could add the m3u thing in here 

            Log.v("URI",getRequest.getURI().toString());

            try {
            HttpResponse httpResponse = httpClient.execute(getRequest);
            if (httpResponse.getStatusLine().getStatusCode() != HttpStatus.SC_OK) {
            // ERROR MESSAGE
            Log.v("HTTP ERROR",httpResponse.getStatusLine().getReasonPhrase());
            }
            else {
                InputStream inputStream = httpResponse.getEntity().getContent(); 
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));

                String line;
                while ((line = bufferedReader.readLine()) != null) { 
                    Log.v("PLAYLISTLINE","ORIG: " + line);

                    if (line.startsWith("#")) {
                        //Metadata
                        //Could do more with this but not fo now
                    } else if (line.length() > 0) {
                        String filePath = "";
                            if (line.startsWith("http://")) {
                            // Assume its a full URL 
                                filePath = line;
                            } else {
                            //Assume it’s relative
                            filePath = getRequest.getURI().resolve(line).toString();
                            }

                            PlaylistFile playlistFile = new PlaylistFile(filePath);
                            playlistItems.add (playlistFile);
                            }
                            }
                            inputStream.close();
                            }
                            } catch (ClientProtocolException e) { 
                                e.printStackTrace();
                            } catch (IOException e) {
                            e. printStackTrace();
                            }


                            currentPlaylistltemNumber = 0;
                            if (playlistItems.size() > 0)
                            {
                            String path = ((PlaylistFile)playlistItems.get(currentPlaylistltemNumber)).getFilePath();
                            try {
                                mediaPlayer.setDataSource(path);

                            mediaPlayer.prepareAsync();}
                            catch (IllegalArgumentException e) 
                            { e.printStackTrace();
                            }catch (IllegalStateException e) { 
                                e.printStackTrace();
                            }catch (IOException e) {
                            e.printStackTrace();}
                            }



            return null;
        }
        //
        protected void onPostExecute(Void result){
            //playButton. setEnabled (false);
        }
    }



    @Override
    public void onStart(Intent intent, int startId) {
        super.onStart(intent, startId);


    }

    public void onDestroy() {
        if (mediaPlayer.isPlaying()) {
            mediaPlayer.stop();
            Log.d(TAG, "music stopp'd");
        }
        //mediaPlayer.release();
        Log.d(TAG, "onDestroy");
    }

    @Override
    public void onPrepared(MediaPlayer mediaPlayer) {
        // TODO Auto-generated method stub\
        Log.d(TAG, "music is prepared and will start");
        mediaPlayer.start();
    }

    public void onCompletion(MediaPlayer _mediaPlayer) {
        Log.d(TAG, "Song completed, next song");
        mediaPlayer.stop();
        mediaPlayer.reset();
            if (playlistItems.size() > currentPlaylistltemNumber + 1) { 
                currentPlaylistltemNumber++;
            String path =
                ((PlaylistFile)playlistItems.get(currentPlaylistltemNumber)).getFilePath();
                try {
                    mediaPlayer.setDataSource(path);
                    mediaPlayer.prepareAsync();
                } catch (IllegalArgumentException e) { 
                    e. printStackTrace();
                } catch (IllegalStateException e) { 
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }   
    }

    class PlaylistFile {
        String filePath;
            public PlaylistFile(String _filePath) {
                filePath = _filePath;
            }
            public void setFilePath(String _filePath) {
                filePath = _filePath;
            }
            public String getFilePath() {
                return filePath;
            }
        }


    public void playSong(){
        Log.d(TAG, "start'd");
        mediaPlayer.start();
    }

    public void pauseSong(){
        Log.d(TAG, "pause'd");
        mediaPlayer.pause();
    }



}

Answer 1

这变得相当复杂，但我使用以下方法查看我的服务是否正在运行:

private boolean isMyServiceRunning() {
ActivityManager manager = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
for (RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
    if ("com.example.MyService".equals(service.service.getClassName())) {
        return true;
    }
}
return false;
}

我将其添加到我的 listview 类中，并在每种情况下放置 if 语句以查看它是否正在运行，如果是则停止 service。

我还公开了所有绑定(bind)连接，以便 ListView 类可以访问它们并在单击时启动它们。

如果有人想进一步了解等，请给我留言。