Android在类外实现BindingAdapter,它从BaseObservable扩展而来

我是我的 User 我有一个 BindingAdapter 它叫什么名字 loadImage 这很好

class User : BaseObservable() {
    var username: String? = null
    var password: String? = null
    var profilePicUrl: String? = null

    companion object {
        @BindingAdapter("android:profilePicUrl")
        fun loadImage(view: ImageView, imageUrl: String) {
            Picasso.get().load(imageUrl).into(view)
        }
    }
}

现在,由于我有更多类似的函数,我想在其他类上使用它们,例如:

object BindingAdapters {
    @JvmStatic
    @BindingAdapter("android:profilePicUrl")
    fun loadImage(view: ImageView, imageUrl: String) {
        Picasso.get().load(imageUrl).into(view)
    }
}

我的问题是我不能把这门课当作 BindingAdapters 在…上 Activity 或者这个活动视图模型,比如 使用者

我的 LoginActivity 课程:

class LoginActivity : AppCompatActivity(), LoginResultCallbacks {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val binding: LoginActivityBinding = DataBindingUtil.setContentView(this, R.layout.login_activity)
        binding.viewModel = ViewModelProviders.of(this, LoginViewModelFactory(this)).get(LoginViewModel::class.java)

    }

    ...
}

LoginViewModel 课程:

public class LoginViewModel extends ViewModel {
    private User user;
    private LoginResultCallbacks loginResultCallbacks;

    public LoginViewModel(LoginResultCallbacks loginResultCallbacks) {
        this.loginResultCallbacks = loginResultCallbacks;
        this.user = new User();
    }
}

LoginViewModelFactory 班

public class LoginViewModelFactory extends ViewModelProvider.NewInstanceFactory {
    private LoginResultCallbacks loginResultCallbacks;

    public LoginViewModelFactory(LoginResultCallbacks loginResultCallbacks) {
        this.loginResultCallbacks = loginResultCallbacks;
    }

    @NonNull
    @Override
    public <T extends ViewModel> T create(@NonNull Class<T> modelClass) {
        return (T) new LoginViewModel(loginResultCallbacks);
    }
}