android - 关于dagger2的几个问题

Question

Scope:@PerActivity 这个注解是怎么起作用的呢？

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

@PerActivity
@Component(dependencies = ApplicationComponent.class, modules = ActivityModule.class)
public interface ActivityComponent {
    void inject(MainActivity mainActivity);
}

 public ActivityComponent getActivityComponent() {
    if (activityComponent == null) {
        activityComponent = DaggerActivityComponent.builder()
                .activityModule(new ActivityModule(this))
                .applicationComponent(DemoApplication.get(this).getComponent())
                .build();
    }
    return activityComponent;
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    getActivityComponent().inject(this);

    mTvUserInfo = (TextView) findViewById(R.id.tv_user_info);
    mTvAccessToken = (TextView) findViewById(R.id.tv_access_token);
}

Answer 1

Hello @PerActivity 是 dagger2 的自定义 Scope ,可以注解在 Component接口、Module的provide方法、构造器注解 @Inject的类 上面，用于实现 此 Scope Local singleton in scope.
Please refer to https://blog.piasy.com//2016/...

Answer 2

It has nothing to do with the name of the annotation, whether it is called PerActivity or ActivityScope. Its scope is determined by who initializes your Component itself. For example, in your example, the Component is built by Activity, and its scope naturally follows that activity