android 教你制作音乐播放器

呵呵，写之前我本人先笑了，欣赏一下我们清爽的界面吧~

如果是只用activity来制作这样的东西简直是太小儿科了，此处我们当然用的是service

首先我们先上service的代码：

1、如果我们要访问service的属性和方法，那么在activity肯定是以bindservice的方法实现的，而在service中的onbind方法也是必须要实现的，onbind返回的Ibinder对象在activity的serviceconnection中得到使用。

2、activity获取到Ibinder对象，可以进一步获取服务对象和player对象，来进行访问。

3、Environment.getExternalStorageDirectory()是获取sd中的内容的，不管是手机出场就已经内置的sd卡，还是用户后来自己添加的sd卡；而getExternalFilesDir()获取的真正是手机内部的存储空间，，/data/data/your_package/，随着应用的卸载存储的文件会被删除。

4、service通过发送广播与activity进行界面交互

public class MusicService extends Service{

    private List<File> musicList;
    private MediaPlayer player;
    private int curPage;
    public static final String MFILTER = "broadcast.intent.action.text";
    public static final String NAME = "name";
    public static final String TOTALTIME = "totaltime";
    public static final String CURTIME = "curtime";

    @Override
    public IBinder onBind(Intent intent) {//1
        // TODO Auto-generated method stub
        return new MBinder();
    }
    public class MBinder extends Binder{//2
        public MusicService getService(){
            return MusicService.this;
        } 
        public MediaPlayer getPlayer(){
            return player;
        }
    }
    @Override
    public void onCreate() {
        // TODO Auto-generated method stub
        super.onCreate();
        musicList = new ArrayList<File>();
        File rootDir = Environment.getExternalStorageDirectory();//3
        Log.d("rootname",rootDir.getName());
        Log.d("rootname",rootDir.getAbsolutePath());
        fillMusicList(rootDir);
        Log.d("musiclist",String.valueOf(musicList.size()));
        player = new MediaPlayer();
        if (musicList.size() != 0) {
            startPlay();
        }
        
        player.setOnCompletionListener(new OnCompletionListener() {
            
            @Override
            public void onCompletion(MediaPlayer mp) {
                // TODO Auto-generated method stub
                player.reset();
                curPage = curPage==musicList.size()-1? (curPage+1)%musicList.size() : curPage+1; 
                startPlay();
            }
        });
    }
    /*迭代获取 音乐 文件*/
    private void fillMusicList(File dir){
        File[] sourceFiles = dir.listFiles();
        Log.d("长度",String.valueOf(sourceFiles.length));
        for(File file : sourceFiles){
            if (file.isDirectory()) {
                Log.d("文件夹名称",String.valueOf(file.getName()));
//                if (!file.getName().equals("lost+found")) {
                    fillMusicList(file);
//                }
                
            }
                else {
                    String name = file.getName();
                    Log.d("childname",file.getName());
                    if (name.endsWith(".mp3")||name.endsWith(".acc")) {//支持的格式
                        musicList.add(file);
                    }
            }
        }
    }
    private void startPlay(){
        mSendBroadCast(NAME,musicList.get(curPage).getName());//4
        try {
            player.setDataSource(musicList.get(curPage).getAbsolutePath());
            player.prepare();
            player.start();
            player.getDuration();
            mSendBroadCast(TOTALTIME,player.getDuration());
            Timer timer = new Timer();
            timer.schedule(new TimerTask() {
                
                @Override
                public void run() {
                    // TODO Auto-generated method stub
                    mSendBroadCast(CURTIME,player.getCurrentPosition());
                }
            },0,1000);
            
        } catch (IllegalArgumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SecurityException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IllegalStateException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }


    public void playNext(){
        curPage = curPage==musicList.size()-1? (curPage+1)%musicList.size() : curPage+1; 
        Log.d("curpage",String.valueOf(curPage));
        player.reset();
        startPlay();
    }
    public void playPrevious(){
        curPage = curPage==0? 0 : curPage-1; 
        Log.d("curpage",String.valueOf(curPage));
        player.reset();
        startPlay();
    }
    public void parse(){
        player.pause();
    }
    public void restart(){
        player.start();
    }
    private void mSendBroadCast(String key, String value){
        Intent intent = new Intent(MFILTER);
        intent.putExtra(key,value);//发送广播
        sendBroadcast(intent);
    }
    
    private void mSendBroadCast(String key, int value){
        Intent intent = new Intent(MFILTER);
        intent.putExtra(key,value);//发送广播
        sendBroadcast(intent);
    }
}

接下来上activity代码：

1、通过Ibinder对象获取服务对象

2、获取到服务对象以后，再访问服务的方法。

3、通过receiver刷新页面

public class MainActivity extends Activity implements OnClickListener{

    SeekBar seekBar;
    TextView curTime,totalTime;
    TextView title;
    
    private ServiceConnection sc;
    private  MusicService ms;
    private boolean isStop;
    private double totalTimeInt; 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        IntentFilter filter = new IntentFilter(MusicService.MFILTER);
        registerReceiver(new MusicReceiver(),filter);
        sc = new ServiceConnection() {
            
            @Override
            public void onServiceDisconnected(ComponentName name) {
                // TODO Auto-generated method stub
                ms = null;
            }
            
            @Override
            public void onServiceConnected(ComponentName name, IBinder service) {
                // TODO Auto-generated method stub
                ms = ((MBinder)service).getService();//1
                
            }
        };
        Button previous = (Button) findViewById(R.id.previous);
        Button next = (Button) findViewById(R.id.next);
        Button stop = (Button) findViewById(R.id.stop);
        Button stopService = (Button) findViewById(R.id.stopService);
        seekBar = (SeekBar) findViewById(R.id.mSeekbar);
        curTime = (TextView) findViewById(R.id.curTime);
        totalTime = (TextView) findViewById(R.id.totalTime);
        title = (TextView) findViewById(R.id.title);
        
        previous.setOnClickListener(this);
        next.setOnClickListener(this);
        stop.setOnClickListener(this);
        stopService.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        switch (v.getId()) {
        case R.id.previous:
            ms.playPrevious();//2
            break;
        case R.id.next:
            ms.playNext();
            break;
        case R.id.stop:
            if (isStop) {
               ms.restart();
            }
            else {
                ms.parse();
            }
            isStop  = !isStop;
            break;
        case R.id.stopService:
            Intent intent = new Intent("com.intent.musicplayer.MusicService");
            unbindService(sc);
            stopService(intent);

            break;
        default:
            break;
        }
    }

    @Override
    protected void onStart() {
        // TODO Auto-generated method stub
        super.onStart();
        Intent intent = new Intent("com.intent.musicplayer.MusicService");
        bindService(intent,sc,Context.BIND_AUTO_CREATE);//当然你可以用startService的方式启动服务，这样结束了activity以后并不会结束service
        
    }
    private String transferMilliToTime(int millis){
        DateFormat format = new SimpleDateFormat("mm:ss");
        String result = format.format(new Date(millis));
        return result;
    }
    private class MusicReceiver extends BroadcastReceiver{//3

        @Override
        public void onReceive(Context context, Intent intent) {
            // TODO Auto-generated method stub
            if (intent.getIntExtra(MusicService.CURTIME,0)!=0) {
                double curTimeInt = intent.getIntExtra(MusicService.CURTIME,0);
                curTime.setText(transferMilliToTime((int)curTimeInt));
                double result = curTimeInt/totalTimeInt*100;
                seekBar.setProgress((int) Math.floor(result));
                
            }
            else if(intent.getIntExtra(MusicService.TOTALTIME,0)!=0) {
                totalTimeInt = intent.getIntExtra(MusicService.TOTALTIME,0);
                totalTime.setText(transferMilliToTime((int)(totalTimeInt)));
            }
            else if (!TextUtils.isEmpty(intent.getStringExtra(MusicService.NAME))) {
                title.setText(intent.getStringExtra(MusicService.NAME));
            }
        }
        
    }
}

4、最后附上xml布局文件，算是代码上传完全了：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="${relativePackage}.${activityClass}" >
    <TextView 
        android:id="@+id/title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:textSize="25sp"
        android:textColor="#444444"
        />
    <SeekBar 
        android:id="@+id/mSeekbar"
        android:layout_gravity="center_horizontal"
        android:layout_width="400dp"
        android:layout_height="wrap_content"
        android:max="100"
        />
    <RelativeLayout 
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        >
        <TextView
        android:id="@+id/curTime"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:layout_alignParentLeft="true"
        
        />
        <TextView
        android:id="@+id/totalTime"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:layout_alignParentRight="true"
        />
    </RelativeLayout>
    <RelativeLayout 
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        >
        <Button
        android:id="@+id/previous"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:text="上一曲"
        android:layout_alignParentLeft="true"
        />
        <Button 
            android:id="@+id/stop"
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:text="停止音乐"
            android:layout_toRightOf="@id/previous"
            />

        <Button
        android:id="@+id/next"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:text="下一曲"
        android:layout_alignParentRight="true"
        />
         <Button 
            android:id="@+id/stopService"
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:text="停止音乐服务"
            android:layout_toLeftOf="@id/next"
            />
    </RelativeLayout>
    

</LinearLayout>