匕首2周期注射

Question

我有两个singletone类，我想将它们注入到Fragments，Activites等中，但我也要将它们注入彼此。 在这一点上，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); 
    } 
} 

我在应用程序类建立图一次。 这里是错误：第一

FATAL EXCEPTION: main java.lang.StackOverflowError at com.aff.index.adverticum.AdverticumChecker_MembersInjector.injectMembers(AdverticumChecker_MembersInjector.java:38) at com.aff.index.adverticum.AdverticumChecker_MembersInjector.injectMembers(AdverticumChecker_MembersInjector.java:8) at com.aff.index.dagger.DaggerAppComponent.inject(DaggerAppComponent.java:679) at com.aff.index.adverticum.AdverticumChecker.(AdverticumChecker.java:50) at com.aff.index.dagger.AdverticumCheckerModule.provideAdverticumChecker(AdverticumCheckerModule.java:30) at com.aff.index.dagger.AdverticumCheckerModule_ProvideAdverticumCheckerFactory.get(AdverticumCheckerModule_ProvideAdverticumCheckerFactory.java:24) at com.aff.index.dagger.AdverticumCheckerModule_ProvideAdverticumCheckerFactory.get(AdverticumCheckerModule_ProvideAdverticumCheckerFactory.java:8) at dagger.internal.DoubleCheck.get(DoubleCheck.java:46) at com.aff.index.adverticum.BannerManager_MembersInjector.injectMembers(BannerManager_MembersInjector.java:67) at com.aff.index.adverticum.BannerManager_MembersInjector.injectMembers(BannerManager_MembersInjector.java:11) at com.aff.index.dagger.DaggerAppComponent.inject(DaggerAppComponent.java:704) at com.aff.index.adverticum.BannerManager.(BannerManager.java:89) at com.aff.index.dagger.BannerManagerModule.provideBannerManager(BannerManagerModule.java:21) at com.aff.index.dagger.BannerManagerModule_ProvideBannerManagerFactory.get(BannerManagerModule_ProvideBannerManagerFactory.java:24) at com.aff.index.dagger.BannerManagerModule_ProvideBannerManagerFactory.get(BannerManagerModule_ProvideBannerManagerFactory.java:8) at dagger.internal.DoubleCheck.get(DoubleCheck.java:46) at com.aff.index.adverticum.AdverticumChecker_MembersInjector.injectMembers(AdverticumChecker_MembersInjector.java:39) at com.aff.index.adverticum.AdverticumChecker_MembersInjector.injectMembers(AdverticumChecker_MembersInjector.java:8) at com.aff.index.dagger.DaggerAppComponent.inject(DaggerAppComponent.java:679)

Answer 1

第一件事，这...

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

规避什么DI代表，基本上依赖注入，而不是在构造函数中注入他们让一些静态访问神奇 - 这种方式AdvertiumChecker几乎不可能测试！列出你所有的依赖构造函数的参数，而不是做这样的：

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

匕首会自动填补国内空白，为你在这里，构建一个适当的图表。其次，如果BannerManager的构建依赖于IAdvertiumChecker的实例，那么您显然会有一个循环依赖关系，Dagger会错误地回答这个问题。通常情况下，这听起来像不好的设计，但有时它不能以不同的方式执行，以防在运行时需要某些东西。

在这种情况下，与Lazy注射，即无论是

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

或

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

希望这有助于工作。