Question

我正在使用JobScheduler作为其AsyncTask的{{1}}。在扩展JobService的类MJobExecutor中，使用了AsyncTask的{{1}}，因为它不起作用。显示无法解决的方法。

MediaPlayer

下面是getApplicationContext()文件。该文件没有问题。

public class MJobExecutor extends AsyncTask<Void,Void,String> {
ValueExchange value;
MediaPlayer player;

@Override
protected String doInBackground(Void... params) {

    value = new ValueExchange();
    Calendar cal = Calendar.getInstance();
    Date date=cal.getTime();
    DateFormat dateFormat = new SimpleDateFormat("hh:mm a");
    String formattedDate=dateFormat.format(date);
    if(formattedDate.equals(value.getString())){

    }
    return "Long running task finishes." + value.getString();
}

private void play(){
    if(player == null){

        player = MediaPlayer.create(getApplicationContext(),R.raw.bensoundfunkyelement);
        //In the above code getApplicationContext() not working-
        //Cannot resolve method getApplicationContext()
        //i have used this as context not working.
        //getBaseActivity() not working.
        //getActivity().getApplicationContext() also not working.


      player.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
            @Override
            public void onCompletion(MediaPlayer mp) {
                stopPlayer();
            }
        });
    }
    player.start();
}
private void stop(){
    stopPlayer();
}
private void stopPlayer(){
    if(player != null){
        player.release();
        player = null;
    }
}


}

下面是扩展MainActivity的{{1}}类，调用了扩展public class MainActivity extends AppCompatActivity { private static final int JOB_ID = 101; JobScheduler jobScheduler; JobInfo jobInfo; TextView textTime; ImageButton ibLeft,ibRight,ibTop,ibBottom; TextClock textClock; String alarmTime = "12:00 AM"; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); textTime = (TextView)findViewById(R.id.textView); ibLeft = (ImageButton)findViewById(R.id.left); ibRight = (ImageButton)findViewById(R.id.right); ibTop = (ImageButton)findViewById(R.id.top); ibBottom = (ImageButton)findViewById(R.id.bottom); textClock.setPadding(0,250,0,0); ComponentName componentName = new ComponentName(this,MJobScheduler.class); PersistableBundle bundle = new PersistableBundle(); bundle.putString("alarmTime",alarmTime); JobInfo.Builder builder = new JobInfo.Builder(JOB_ID,componentName); builder.setExtras(bundle); builder.setPeriodic(5000); builder.setRequiredNetworkType(JobInfo.NETWORK_TYPE_ANY); builder.setPersisted(true); jobInfo = builder.build(); jobScheduler = (JobScheduler) getSystemService(JOB_SCHEDULER_SERVICE); } public void Start(View view) { jobScheduler.schedule(jobInfo); Toast.makeText(this,"Job Started...",Toast.LENGTH_LONG).show(); } public void Stop(View view) { jobScheduler.cancel(JOB_ID); Toast.makeText(this,"Job Cancelled...",Toast.LENGTH_LONG).show(); } }的{{1}}类。看来这堂课也没问题。

MjobExecutor

Answer 1

您不能从getApplicationContext()内部调用AsyncTask，因为该方法是在Context类中定义的，而不是在AsyncTask类中定义的。仅供参考，您可以在Activity或Service或其子类中使用此方法，因为这些类是Context的子类。

为了解决您的问题，您将需要通过构造函数或setter在您的Context中传递一个MediaPlayer对象或一个AsyncTask对象。

例如：

public class YourTask extends AsyncTask<Void, Void, String> {

    private MediaPlayer player;

    public YourTask(MediaPlayer player) {
        this.player = player;
    }

    @Override
    protected String doInBackground(Void... voids) {
        // todo
        return null;
    }

}

Answer 2

AsyncTask类MJobExecutor应该具有传递上下文或媒体播放器对象的构造器

    public class MJobExecuter extends AsyncTask<Void, Void, String> {

private Context context;

public YourTask(Context context) {
    this.context = context;
}

@Override
protected String doInBackground(Void... voids) {
    // todo
    return null;
}

    }

然后在扩展了调用AsyncTask的服务的MJobScheduler类中，应如图所示传递Context。

    public class MJobScheduler extends JobService {
    MJobExecutor mJobExecutor;
    String alarmTime;
    ValueExchange value;

    @Override
    public boolean onStartJob(final JobParameters params) {
        alarmTime = params.getExtras().getString("alarmTime");
value = new ValueExchange();
value.setString(alarmTime);
mJobExecutor = new MJobExecutor(getApplicationonContext()){//pass context here..

    @Override
    protected void onPostExecute(String s) {
        Toast.makeText(getApplicationContext(),alarmTime+" "+s,Toast.LENGTH_LONG).show();
        jobFinished(params,false);
    }
};
mJobExecutor.execute();
return true;
    }

    @Override
    public boolean onStopJob(JobParameters params) {
mJobExecutor.cancel(false);
return false;
    }
    }

getApplicationContext（）不适用于将AsyncTask用于JobService的JobScheduler

2 个答案: