令人惊讶的是,我正在努力获取源自以下内容的服务实例:MediaBrowserServiceCompat
.
对于典型的服务,为了实现这一点,使用本地绑定器
class MyService extends MediaBrowserServiceCompat {
class MyBinder extends Binder {
public MyService getService() {
return MyService.this;
}
private final MyBinder binder = new MyBinder();
@Override
public IBinder onBind(Intent intent) {
return binder;
}
public void doMagic() { // <-- How to call this from activity?
// ...
}
}
// At the activity, for example, this binder is retrieved through
// `onServiceConnected()`, typecast to `MyBinder` and thus
// `getService()` gets us the service instance.
但是,这不适用于派生自的服务MediaBrowserServiceCompat
.
当我尝试提供本地活页夹时,如上所示,服务崩溃了MediaBrowserServiceCompat
期望有自己的自定义活页夹并具有附加功能。这是崩溃堆栈跟踪
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
at android.os.Binder.queryLocalInterface(Binder.java:254)
at android.service.media.IMediaBrowserService$Stub.asInterface(IMediaBrowserService.java:31)
at android.media.browse.MediaBrowser$MediaServiceConnection.onServiceConnected(MediaBrowser.java:793)
at android.app.LoadedApk$ServiceDispatcher.doConnected(LoadedApk.java:1223)
at android.app.LoadedApk$ServiceDispatcher$RunConnection.run(LoadedApk.java:1240)
at android.os.Handler.handleCallback(Handler.java:746)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5443)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
我尝试将活页夹包裹起来MediaBrowserServiceCompat
超级类,如下所示,但仍然行不通。
class MyService extends MediaBrowserServiceCompat {
class MyBinder extends Binder {
public MyService getService() {
return MyService.this;
}
private final WrappingBinder<MyService> binder;
@Override
public IBinder onBind(Intent intent) {
if (binder == null) {
binder = new WrappingBinder(super.onBind(intent));
}
return binder;
}
public void doMagic() { // <-- How to call this from activity or elsewhere?
// ...
}
}
那么想知道访问 MediaBrowserServiceCompat 服务实例的方法是什么?
需要明确的是,播放功能对我来说运行良好。问题是如何获取对该服务的引用,以便我可以调用该服务上的自定义公共方法。