调度执行mediaplayer在android

Question

我是Android开发新手，我需要一些帮助来解决一个小问题。我有一个后台服务，运行我的媒体播放器，并与我的PlayerActivity通信。到目前为止一切顺利。

我需要安排不同时期的曲目执行。例如，播放音轨x一分钟，播放音轨y 30秒，等等。

所以我从PlayerActivity调用MyTimer线程，这个线程在特定的时间抛出事件，
PlayerActivity捕获事件并调用MediaplayerService next()方法。我的问题是，如果我调用next()没有线程它工作得很好，如果我调用它与线程，我得到

 mContext is null, can't getMirrorDisplayStatus!!!

with mediaplayer warning (1,2002)我试图通过Handler.post()和runOnUiThread()从PlayerActivity运行这个线程我得到同样的错误

下面是MyTimer线程的代码。

public class MyTimer implements Runnable {

private Object mPauseLock;
private boolean mPaused;
private boolean mFinished;
private TimeSection section;

public Trainer()
{
    mPauseLock = new Object();
    mPaused = false;
    mFinished = false;
    BusProvider.getInstance().register(this);
}

@Override
public void run()
{
    while (!mFinished)
    {
        TimerManager tm = TimerManager.getInstace();
        this.section = tm.getCurrentTimeSection();
        if(this.section == null)
            mFinished = true;
        else
        {
            tm.inc();
            // produce sectionChangeEvent event
            BusProvider.getInstance().post(produceSectionEvent());
            try
            {
                Thread.sleep((this.section.getTypeDuration() * 1000));
            } catch (InterruptedException e)
            {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        synchronized (mPauseLock)
        {
            while (mPaused)
            {
                try
                {
                    mPauseLock.wait();
                } catch (InterruptedException e)
                {
                }
            }
        }
    }
}
  /**
 * Call this on pause.
 */
public void onPause() {
    synchronized (mPauseLock) {
        mPaused = true;
    }
}
/**
 * Call this on resume.
 */
public void onResume() {
    synchronized (mPauseLock) {
        mPaused = false;
        mPauseLock.notifyAll();
    }
}
@Produce public TimeSectionEvent produceSectionEvent(){
    return new TimeSectionEvent(this.section);
}

}

一些玩家活动的代码:

public class PlayerActivity implements
    IMediaPlayerServiceClient{
private MediaPlayerService mService;
....
/**
 * Binds to the instance of MediaPlayerService. If no instance of
 * MediaPlayerService exists, it first starts a new instance of the service.
 */
public void bindToService()
{
    Intent intent = new Intent(this, MediaPlayerService.class);
    if (MediaPlayerServiceRunning())
    {
        // Bind to LocalService
        bindService(intent, mConnection, Context.BIND_AUTO_CREATE);
    } else
    {
        startService(intent);
        bindService(intent, mConnection, Context.BIND_AUTO_CREATE);

    }
}
.....
/*
* This is how I start the timing thread
*/
private void startTiming()
{
    mTimer = new MyTimer();
    runOnUiThread(mTimer);
//  trainingHandler.post(mTrainer);
}
public void next(TimeSection section)
{
    mService.next(section);
}
/*
* Here I catch the TimeSectionEvent from MyTimer thread
*/
@Subscribe public void onSectionChanged(TimeSectionEvent e)
{
    TimeSection section = e.getSection();
    if(section != null)
         next(section);
}

Answer 1

每个活动都有上下文，所以从异常，你得到我猜这是一个问题与MediaPlayerService的上下文。

你正在使用bindService(…)将意图绑定到应该绑定上下文的MediaPlayerService。

尝试检查绑定是否仍然存在，当你试图执行"mService.next(section);"

Answer 2

问题解决!

问题是，我是计时线程运行在UI线程->调用Thread.sleep使UI线程睡眠以及。所以我最终使用IntentService在后台做定时器线程工作。

public class TimingService extends IntentService{
private Object mPauseLock;
private boolean mPaused;
private boolean mFinished;
private TimeSection section;
public TimingService()
{
    super("TimingService");
    mPauseLock = new Object();
    mPaused = false;
    mFinished = false;
    BusProvider.getInstance().register(this);
}
@Override
protected void onHandleIntent(Intent intent)
{
    while (!mFinished)
{
    TimerManager tm = TimerManager.getInstace();
    this.section = tm.getCurrentTimeSection();
    if(this.section == null)
        mFinished = true;
    else
    {
        tm.inc();
        // produce sectionChangeEvent event
        BusProvider.getInstance().post(produceSectionEvent());
        try
        {
            Thread.sleep((this.section.getTypeDuration() * 1000));
        } catch (InterruptedException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    synchronized (mPauseLock)
    {
        while (mPaused)
        {
            try
            {
                mPauseLock.wait();
            } catch (InterruptedException e)
            {
            }
        }
    }
}
}
  /**
 * Call this on pause.
 */
public void onPause() {
    synchronized (mPauseLock) {
        mPaused = true;
    }
}
/**
 * Call this on resume.
 */
public void onResume() {
    synchronized (mPauseLock) {
        mPaused = false;
        mPauseLock.notifyAll();
    }
}
@Produce public TimeSectionEvent produceSectionEvent(){
return new TimeSectionEvent(this.section);
}
@Subscribe
public void onPauseEvent(PauseEvent e)
{
    this.onPause();
}
@Subscribe
public void onResumeEvent(ResumeEvent e)
{
    this.onResume();
}
}