Dagger-Android Activity 继承注入："This type supports members injection but cannot be implicitly provided."

Question

我有三个活动，它们通过继承相关联。

这些活动中只有一个使用片段注入。

其中两项活动需要 Dagger 2 activity 注射。第三个activity不需要任何注射。

这是我的活动：

/**
 * Needs activity injection.
 */
class ThirdActivity extends SecondActivity
{
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        // calls the super, which will call AndroidInjection.inject(this);
        // ... other code not shown
    }
}

/**
 * This activity requires fragment injection
 */
class SecondActivity extends FirstActivity
{

    @Inject
    DispatchingAndroidInjector<Fragment> fragmentInjector;

    @Override
    public AndroidInjector<Fragment> supportFragmentInjector()
    {
        return fragmentInjector;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        AndroidInjection.inject(this);
        super.onCreate(savedInstanceState);
    }
} 

/**
 * Does not use injection.
 */
class FirstActivity extends Activity
{
    // no injection required
}

这是我的 Dagger 2 模块

@Module
abstract class AppModule
{
    @ActivityScope
    @ContributesAndroidInjector(modules = {ThirdActivityModule.class, SecondActivityModule.class})
    abstract ThirdActivity contributeThirdActivityInjector();

    @ActivityScope
    @ContributesAndroidInjector(modules = {SecondActivityModule.class})
    abstract SecondActivity contributeSecondActivityInjector();
}

@Module
abstract class SecondActivityModule
{
    @Binds
    abstract Activity bindActivity(SecondActivity secondActivity);

    @FragmentScope
    @ContributesAndroidInjector(modules = {MyFragmentModule.class})
    abstract MyFragment contributeMyFragmentInjector();
}

@Module
public abstract class ThirdActivityModule
{
    @Binds
    abstract Activity bindActivity(ThirdActivity thirdActivity);
}

@Module
abstract class MyFragmentModule
{
    @Binds
    abstract Fragment bindFragment(MyFragment mFragment);
}

我得到的错误是：

Note: Recompile with -Xlint:unchecked for details.
/dagger/AppComponent.java:45: error: [Dagger/MissingBinding] 
[dagger.android.AndroidInjector.inject(T)] 
com.example.SecondActivity cannot be provided without an @Inject constructor or an @Provides-annotated method. 
This type supports members injection but cannot be implicitly provided.

我认为这可能是因为我在 contributesThirdActivityInjector() 调用中包含了 SecondActivityModule 和 ThirdActivityModule，但我不确定。

任何 help/advice 在继承的情况下使用 activity/fragment 注入将不胜感激。

Answer 1

在ThirdActivityModule中尝试将bindActivity的return类型改为SecondActivity:

@Module
public abstract class ThirdActivityModule {
    /**
     * Upcasts ThirdActivity to SecondActivity. SecondActivityModule will do
     * the rest to upcast it to Activity.
     */
    @Binds
    abstract SecondActivity bindActivity(ThirdActivity thirdActivity);
}

我怀疑 Dagger 想要 Activity 来满足某处的依赖请求，并且根据 SecondActivityModule.bindActivity 的 @Binds 规则，Dagger 必须以某种方式获得 SecondActivity。

然后这个修改后的 ThirdActivityModule.bindActivity 让 Dagger 知道它可以将 ThirdActivity 视为 SecondActivity。

Dagger-Android Activity 继承注入："This type supports members injection but cannot be implicitly provided."

Dagger-Android Activity injection with inheritance: "This type supports members injection but cannot be implicitly provided."

java

android

dagger

dagger-2