Dagger 2 基类注入

在 Dagger 1 中，我有一个基类设置，以便它可以处理创建作用域图并将依赖项注入当前对象。例如...

public abstract class MyBaseActivity extends Activity {
  private ObjectGraph graph;

  protected void onCreate(Bundle savedInstanceState) {
    graph = ((MyApp) getApplication()).plus(getModules());
    graph.inject(this);
  }

  protected Object[] getModules();
}

public class MyClass extends MyBaseActivity {

  @Inject SomeDep someDep;

  @Override
  protected Object[] getModules() {
    return new Object[/* Contains a module that provides SomeDep */];
  }
}

这使得每个子类除了标准应用程序模块之外还可以补充自己的模块集。

在玩过 Dagger 2 后，似乎无法处理类似的场景......

public abstract class MyBaseActivity extends Activity {
  private MyBaseActivityComponent component;

  protected void onCreate(Bundle savedInstanceState) {
    component = ((MyApp) getApplication()).component().plus(/* Can not accept an array */);
    component.inject(this);
  }
}

我通过修改 MyBaseActivityComponent 来解决上述问题，以便它列出它可能使用的所有可能的模块...

@Subcomponent(modules = {
  Module1.class,
  Module2.class
})
public interface MyBaseActivityComponent {
  public void inject(MyBaseActivity activity);
}

所以现在我可以做这样的事情......

public abstract class MyBaseActivity extends Activity {
  private MyBaseActivityComponent component;

  protected void onCreate(Bundle savedInstanceState) {
    component = ((MyApp) getApplication()).component().plus(new Module1(), new Module2());
    component.inject(this);
  }
}

但现在我遇到一个问题，注入将注入 MyBaseActivity 的依赖项，而不是它的子类。建议？

理论上，你可以这样做。

1.) 指定子范围

@Scope
@Retention(RUNTIME)
public @interface PerActivity {
}

2.) 指定父组件

@Singleton
@Component(modules={Module1.class, Module2.class)
public interface MyApplicationComponent {
    Dependency1 providesDependency1();
    Dependency2 providesDependency2();
}

3.) 指定子组件

@PerActivity
@Component(dependencies={MyApplicationComponent.class}, modules={Module3.class})
public interface MyBaseActivityComponent extends MyApplicationComponent {
    void inject(BaseActivity baseActivity);

    Dependency3 providesDependency3();
}

4.) 创建您的模块

@Module
public class Module3 {
     @Provides
     @PerActivity
     public Dependency3 providesDependency3() {
         return new Dependency3();
     }
}

5.) 创建 Activity 级别的作用域组件

public class BaseActivity extends AppCompatActivity {
    private MyBaseActivityComponent baseComponent;

    @Override
    public void onCreate(Bundle saveState) {
        super.onCreate(saveState);
        baseComponent = DaggerBaseActivityComponent.builder()
                    .applicationComponent(((MyApp)getApplication()).component())
                    .build();
    }

    public MyBaseActivityComponent baseComponent() {
        return baseComponent;
    }

    @Override
    public void onDestroy() {
        component = null;
        super.onDestroy();
    }
}

如果有效，请回复，之前我忘记在我的中指定依赖项Component并出现编译错误，但它应该像这样工作。

另外，如果您需要为每个指定一个子组件Activity，那么您只需在中使用提供方法指定依赖项BaseActivityComponent成分...

@PerActivity
@Component(dependencies={MyBaseActivityComponent.class}, modules={Module4.class})
public interface MyActivityComponent extends MyBaseActivityComponent {
    public void inject(MyActivity myActivity);

    Dependency4 providesDependency4();
}

@Module
public class Module4 {
    @PerActivity
    @Provides
    public Dependency4 providesDependency4(Dependency3 dependency3) {
        return new Dependency4(dependency3);
    }
}

public class MyActivity extends MyBaseActivity {
    private MyActivityComponent component;

    @Override
    public void onCreate(Bundle saveInstanceState) {
        super.onCreate(saveInstanceState);
        component = DaggerMyActivityComponent.builder()
           .applicationComponent(((MyApp)getApplication()).component())
           .myBaseActivityComponent(baseComponent())
           .build();
    }

    @Override
    public void onDestroy() {
        component = null;
        super.onDestroy();
    }
}

EDIT: @Subcomponent根据以下内容，使用子组件工厂方法替换组件依赖关系the docs http://google.github.io/dagger/api/latest/dagger/Component.html仅当您使用以下模式时（也称为使用供应/工厂方法定义将子组件嵌入父组件中）：

   @Singleton @Component
   interface ApplicationComponent {
     // component methods...

     RequestComponent newRequestComponent(RequestModule requestModule);
   }

Where

  @Subcomponent(modules={RequestModule.class})
  interface RequestComponent {
       RequestSomething requestSomething();
  }