不知道为什么dagger2注入的对象在presenter中为null

Question

不知道为什么dagger2注入的MainRankPresenter.java的loginResponseHandler在MainRankPresenter中为null。我只想注入字段进行字段注入。我应该做其他方式而不是现场注入吗？请让我知道如何解决它。

BBBApplication.java

public class BBBApplication extends MultiDexApplication
{
    ...
    @Override
    public void onCreate() {
        super.onCreate();

        initAppComponent();
    }

    private void initAppComponent() {
        this.appComponent = DaggerAppComponent.builder()
            .appModule(new AppModule(this))
            .build();
    }

    public static BBBApplication get(Context ctx) {
        return (BBBApplication) ctx.getApplicationContext();
    }
    public AppComponent getAppComponent() {
        return this.appComponent;
    }
    ...
}

AppModule.java

@Module
public class AppModule {
    private BBBApplication application;

    public AppModule(BBBApplication application) {
        this.application = application;
    }

    @Provides
    @Singleton
    public Application provideApplication() {
        return this.application;
    }

    @Provides
    @Singleton
    public Resources provideResources() {
        return this.application.getResources();
    }

    @Provides`enter code here`
    @Singleton
    public SharedPreferences provideSharedPreferences() {
        return PreferenceManager.getDefaultSharedPreferences(this.application);
    }
}

AppComponent.java

@Singleton
@Component(modules = {AppModule.class, ServiceModule.class})
public interface AppComponent {
    RankFragmentComponent plus(RankFragmentModule module);

    Application application();
    Resources resources();
}

RankFragmentModule.java

@Module
public class RankFragmentModule {

    private RankFragment rankFragment;

    public RankFragmentModule(RankFragment rankFragment) {
        this.rankFragment = rankFragment;
    }

    @Provides
    @ActivityScope
    public LoginResponseHandler provideLoginResponseHandler() {
        return new LoginResponseHandler(this.rankFragment);
    }

    @Provides
    @ActivityScope
//    @Named("rankFragment")
    public RankFragment provideRankFragment() {
        return this.rankFragment;
    }

    @Provides
    @ActivityScope
    public MainRankPresenter provideMainRankPresenter(RankFragment rankFragment) {
        return new MainRankPresenter(new MainRankViewOps(rankFragment));
    }

}

RankFragmentComponent.java

@ActivityScope
@Subcomponent(modules = {RankFragmentModule.class})
public interface RankFragmentComponent {
    void inject(RankFragment rankFragment);
}

RankFragment.java

public class RankFragment extends Fragment {

    @Inject
    MainRankPresenter presenter;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        BBBApplication.get(getContext())
                .getAppComponent()
                .plus(new RankFragmentModule(this))
                .inject(this);
        presenter.test();
    }

MainRankPresenter.java

public class MainRankPresenter implements Presenter {

    private MainRankViewOps viewOps;

    @Inject
    LoginResponseHandler loginResponseHandler;

    @Inject
    public MainRankPresenter(MainRankViewOps viewOps) {
        this.viewOps = viewOps;
    }

    @Override
    public void test() {
        Log.d(Constants.TAG_DEBUG, "=== presenter test" + this.toString());
        Log.d(Constants.TAG_DEBUG, "=== " + loginResponseHandler.toString());
        this.viewOps.initViewOps();
    }
}

MainRankViewOps.java

public class MainRankViewOps implements ViewOps {

    RankFragment fragment;

    @Inject
    public MainRankViewOps(RankFragment fragment) {
        this.fragment = fragment;
    }

    @Override
    public void initViewOps() {
        Log.d(Constants.TAG_DEBUG, "=== view ops" + this.toString());
        Log.d(Constants.TAG_DEBUG, "=== " + fragment.toString());
    }
}

Answer 1

Dagger 2 的注入不是递归的。因此，当您在 RankFragment 中调用 inject(this) 时，只会注入该片段的 @Inject 注释字段。 Dagger 2 不会在注入的对象中搜索 @Inject 注释。

一般来说，您应该尝试将依赖注入框架的使用限制在 "top-level" 组件（活动、片段、服务等），这些组件由 Android 框架为您实例化。在您自己实例化的对象中（如 MainRankPresenter），您应该使用其他不涉及外部框架的 DI 技术（例如，向构造函数中注入依赖项）。

Answer 2

因为您 @Provides MainRankPresenter，Dagger 不会注入它：您对此负责。你可能让你的 provides 方法被传递一个 MembersInjector si 你可以在返回它之前注入字段，但是最好重构你删除的提供方法的模块并让 Dagger 处理注入（您已经拥有所有需要的 @Inject）

不知道为什么dagger2注入的对象在presenter中为null

I don't know why the object injected by dagger2 is null in presenter

mvp

android

dagger