android - Dagger 2 基类注入(inject)

Question

在 Dagger 1 中，我有一个基类设置，它可以处理创建范围图并将依赖项注入(inject)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 */];
  }
}

这允许每个子类在标准应用程序模块之外补充他们自己的模块集。

在玩过 Dagger 2 之后，似乎无法处理类似的情况......

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，以便列出它可能使用的所有可能模块......

@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);
  }
}

但是现在我遇到了一个问题，注入(inject)将注入(inject) MyBaseActivity 的依赖项，而不是它的子类。建议？

Answer 1

从理论上讲，您可以这样做。

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.) 创建你的模块

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

5.) 创建 Activity 级范围组件

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 Component 中指定依赖项并得到编译错误，但它应该像这样工作。

此外，如果您需要为每个 Activity 指定一个子组件，那么您可以在 BaseActivityComponent 中使用配置方法指定依赖项零件...

@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();
    }
}

编辑 : @Subcomponent根据 the docs 使用子组件工厂方法替换组件依赖项仅当您使用以下模式(也就是使用供应/工厂方法定义将子组件嵌入父组件中)时:

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

     RequestComponent newRequestComponent(RequestModule requestModule);
   }

在哪里

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