java - 如何将 MediaPlayer 对象从 JobScheduler 的 JobService 传递给 AsyncTask
问题描述
我正在使用 JobScheduler,它使用 AsyncTask 作为其 JobService。在扩展 AsyncTask 的类 MJobExecutor 中使用 MediaPlayer。我想传递媒体播放器对象,但是如何传递。以下是我的名为 MJobExecutor.java 的 AsyncTask 类的代码,我创建了一个构造函数来传递 MediaPlayer 对象。但代码似乎不起作用。
public class MJobExecutor extends AsyncTask<Void,Void,String> {
ValueExchange value;
private MediaPlayer player;
//Constructor to pass MediaPlayer object.
public MJobExecutor(MediaPlayer player){
this.player = 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())){
}
play();
return "Long running task finishes." + value.getString();
}
private void play(){
if(player == null){
//Below the getApplicationContext() not working even after the constructor-
//being declared.
player = MediaPlayer.create(getApplicatioContext(),R.raw.bensoundfunkyelement);
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;
}
}
}
再次在扩展 JobService 的 MJobScheduler.java 类中,传递了 MediaPlayer 对象。但它不起作用。
public class MJobScheduler extends JobService {
MJobExecutor mJobExecutor;
String alarmTime;
ValueExchange value;
MediaPlayer player;
@Override
public boolean onStartJob(final JobParameters params) {
alarmTime = params.getExtras().getString("alarmTime");
value = new ValueExchange();
value.setString(alarmTime);
//MediaPlayer object is Passed into the constructor-
//but the app crashes
mJobExecutor = new MJobExecutor(player){
@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;
}
}
Main Activity 类如下...
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();
}
}
解决方案
在类中实例化您的MediaPlayer
对象,MJobScheduler
这样您的AsyncTask
.
player = MediaPlayer.create(getApplicatioContext(),R.raw.bensoundfunkyelement);
将上面的行从您play
的类中的方法移动到该行之前的类MJobExecutor
的方法onStartJob
MJobScheduler
mJobExecutor = new MJobExecutor(player)...
然后在你的方法play
中,删除条件检查if(player == null)
,因为它总是错误的,阻止其中的代码被执行。
因此,您的方法主体onStartJob
如下:
alarmTime = params.getExtras().getString("alarmTime");
value = new ValueExchange();
value.setString(alarmTime);
player = MediaPlayer.create(getApplicatioContext(), R.raw.bensoundfunkyelement);
mJobExecutor = new MJobExecutor(player){
@Override
protected void onPostExecute(String s) {
Toast.makeText(getApplicationContext(),alarmTime+" "+s,Toast.LENGTH_LONG).show();
jobFinished(params,false);
}
};
mJobExecutor.execute();
return true;
您的play
方法如下:
private void play() {
player.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
@Override
public void onCompletion(MediaPlayer mp) {
stopPlayer();
}
});
player.start();
}
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