Question

我有两个单音类我想将它们注入Fragments，Activites等，但我也要将它们注入彼此。在那一点上，我总是得到SO错误。

public class AdverticumChecker implements IAdverticumChecker {

    @Inject BannerManager bannerManager;

    public AdverticumChecker(Context context) {
        IndexApplication.getApplication().getAppComponent().inject(this);
    }
}

public class BannerManager {
    @Inject IAdverticumChecker adverticumChecker;

    public BannerManager(){
        IndexApplication.getApplication().getAppComponent().inject(this);
    }
}

这些是模块

@Module
public class BannerManagerModule {

        @Singleton
        @Provides
        BannerManager provideBannerManager(){
            return new BannerManager();
        }
    }

@Module
public class AdverticumCheckerModule {
    private Context context;

    public AdverticumCheckerModule(Context context){
        this.context = context;
    }

    @Singleton
    @Provides
    IAdverticumChecker provideAdverticumChecker(){
        return new AdverticumChecker(context);
    }
}

我在Application类中构建了一次图。这是错误：

致命的例外：主要 java.lang.StackOverflowError的在 com.aff.index.adverticum.AdverticumChecker_MembersInjector.injectMembers（AdverticumChecker_MembersInjector.java:38）在 com.aff.index.adverticum.AdverticumChecker_MembersInjector.injectMembers（AdverticumChecker_MembersInjector.java:8）在 com.aff.index.dagger.DaggerAppComponent.inject（DaggerAppComponent.java:679）在 com.aff.index.adverticum.AdverticumChecker。（AdverticumChecker.java:50）在 com.aff.index.dagger.AdverticumCheckerModule.provideAdverticumChecker（AdverticumCheckerModule.java:30）在 com.aff.index.dagger.AdverticumCheckerModule_ProvideAdverticumCheckerFactory.get（AdverticumCheckerModule_ProvideAdverticumCheckerFactory.java:24）在 com.aff.index.dagger.AdverticumCheckerModule_ProvideAdverticumCheckerFactory.get（AdverticumCheckerModule_ProvideAdverticumCheckerFactory.java:8）在dagger.internal.DoubleCheck.get（DoubleCheck.java:46）在 com.aff.index.adverticum.BannerManager_MembersInjector.injectMembers（BannerManager_MembersInjector.java:67）在 com.aff.index.adverticum.BannerManager_MembersInjector.injectMembers（BannerManager_MembersInjector.java:11）在 com.aff.index.dagger.DaggerAppComponent.inject（DaggerAppComponent.java:704）在 com.aff.index.adverticum.BannerManager。（BannerManager.java:89）在 com.aff.index.dagger.BannerManagerModule.provideBannerManager（BannerManagerModule.java:21）在 com.aff.index.dagger.BannerManagerModule_ProvideBannerManagerFactory.get（BannerManagerModule_ProvideBannerManagerFactory.java:24）在 com.aff.index.dagger.BannerManagerModule_ProvideBannerManagerFactory.get（BannerManagerModule_ProvideBannerManagerFactory.java:8）在dagger.internal.DoubleCheck.get（DoubleCheck.java:46）在 com.aff.index.adverticum.AdverticumChecker_MembersInjector.injectMembers（AdverticumChecker_MembersInjector.java:39）在 com.aff.index.adverticum.AdverticumChecker_MembersInjector.injectMembers（AdverticumChecker_MembersInjector.java:8）在 com.aff.index.dagger.DaggerAppComponent.inject（DaggerAppComponent.java:679）

Answer 1

首先，这是......

@Singleton
@Provides
IAdverticumChecker provideAdverticumChecker(){
    return new AdverticumChecker(context);
}
...
public AdverticumChecker(Context context) {
    IndexApplication.getApplication().getAppComponent().inject(this);
}

规避DI代表什么，基本上注入依赖关系，而不是让构造函数中的某些静态访问器神奇地注入它们 - 这样AdvertiumChecker几乎不可能测试！将所有依赖项列为构造函数参数，并按以下方式执行：

@Singleton
@Provides
IAdverticumChecker provideAdverticumChecker(BannerManager bannerManager){
    return new AdverticumChecker(bannerManager);
}
...
private BannerManager mBannerManager;
public AdverticumChecker(BannerManager bannerManager) {
    mBannerManager = bannerManager;
}

Dagger会在这里为你自动填补空白并构建一个合适的图表。

其次，如果BannerManager的构造依赖于IAdvertiumChecker的实例，那么你显然会有一个Dagger错误的循环依赖关系。通常这有点像糟糕的设计，但有时它不可能有所不同，以防你在运行时需要一些东西。

在这些情况下，使用Lazy注射，即

@Inject
Lazy<BannerManager> mLazyBannerManager;
...
mLazyBannerManager.get().doSomething();

或

IAdvertiumChecker providerAdvertiumChecker(Lazy<BannerManager> lazyBannerManager) {
    return new AdverticumChecker(lazyBannerManager);
}

希望这有帮助。

Dagger 2循环注射

1 个答案: