Binder 必须是一个内部 class 吗？

Question

我正在阅读 Android 绑定服务，http://developer.android.com/guide/components/bound-services.html

public class LocalService extends Service {
// Binder given to clients
private final IBinder mBinder = new LocalBinder();
// Random number generator
private final Random mGenerator = new Random();

/**
 * Class used for the client Binder.  Because we know this service always
 * runs in the same process as its clients, we don't need to deal with IPC.
 */
public class LocalBinder extends Binder {
    LocalService getService() {
        // Return this instance of LocalService so clients can call public methods
        return LocalService.this;
    }
}

@Override
public IBinder onBind(Intent intent) {
    return mBinder;
}

/** method for clients */
public int getRandomNumber() {
  return mGenerator.nextInt(100);
}

}

所有教程、android 开发人员指南和书籍都建议将 Binder 作为服务的内部 class。真的只能是内部 class 吗？

Answer 1

它是一个内部 class，因此您可以轻松 return 外部 Service 实例。您也可以将其设为外部 class:

public class LocalBinder extends Binder {

  private final LocalService mLocalService;

  public LocalBinder(final LocalService service) {
    mLocalService = service;
  }

  LocalService getService() {
    return mLocalService;
  }
}

使用内部 class 可以避免创建字段和构造函数的麻烦。

Binder 必须是一个内部 class 吗？

Does Binder have to be an inner class?

android

android-service

android-service-binding