我在将服务绑定到活动时遇到问题。我得到playing_service==null。我找不出我做错了什么。为什么playing_service为空??
MyActivity类:
private playService playing_service=null;
private ServiceConnection service_conn=new ServiceConnection(){
public void onServiceConnected(ComponentName className, IBinder service) {
LocalBinder binder=(LocalBinder)service;
playing_service=binder.getService();
}
public void onServiceDisconnected(ComponentName arg0) {
// TODO Auto-generated method stub
}
};
public void playTrack(View view){
Intent i=new Intent(this,playService.class);
i.setAction("com.c0dehunter.soundrelaxer.PLAY");
bindService(i,service_conn,Context.BIND_AUTO_CREATE);
if(playing_service==null) //here I get true,
//if I try to access playing_service I get NullPointerException
}
}
播放服务类:
private final IBinder binder=new LocalBinder();
public int onStartCommand(Intent intent, int flags, int startId){
return 1; //dummy
}
@Override
public IBinder onBind(Intent intent) {
// TODO Auto-generated method stub
return binder;
}
public class LocalBinder extends Binder{
public playService getService(){
return playService.this;
}
}
您的服务可能不是null,因为绑定服务是一种asynchronous
方法,所以您不应该在调用绑定方法后检查服务的可用性,而是应该在服务连接实现中进行检查,例如:
private ServiceConnection service_conn=new ServiceConnection(){
public void onServiceConnected(ComponentName className, IBinder service) {
LocalBinder binder=(LocalBinder)service;
playing_service=binder.getService();
if(playing_service != null){
Log.i("service-bind", "Service is bonded successfully!");
//do whatever you want to do after successful binding
}
}
public void onServiceDisconnected(ComponentName arg0) {
// TODO Auto-generated method stub
}
};