扩展类的 CDI 模糊分辨率

Question

我需要将CacheService 注入到各种bean 中，并维护CacheService 的单例扩展，称为ResourceCacheService。

interface CacheService{}
@Default
class CacheServiceImpl implements CacheService{}
@Singleton
class ResourceCacheService extends CacheServiceImpl{}

或者更好：

interface ResourceCacheService extends CacheService{}
@Singleton
class ResourceCacheServiceImpl extends CacheServiceImpl{}

无论哪种方式，我都会遇到一个模棱两可的异常。如何在需要的地方注入 CacheService 的新实例，以及创建它的 Singleton 版本？

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更新 - 添加异常

Caused by: org.apache.openejb.OpenEJBRuntimeException: org.apache.webbeans.exception.WebBeansDeploymentException: javax.enterprise.inject.AmbiguousResolutionException: There is more than one Bean with type com.project.cache.CacheServiceQualifiers: [@javax.enterprise.inject.Default()]

ResourceCacheService, WebBeansType:MANAGED, Name:null, API Types:[com.project.web.ResourceCacheService,com.project.cache.CacheService,java.lang.Object,com.project.cache.CacheServiceImpl], Qualifiers:[javax.enterprise.inject.Default,javax.enterprise.inject.Any] from file:/application/webapps/ROOT/WEB-INF/classes/com/project/web/ResourceCacheService.class
CacheServiceImpl, WebBeansType:MANAGED, Name:null, API Types:[com.project.cache.CacheService,java.lang.Object,com.project.cache.CacheServiceImpl], Qualifiers:[javax.enterprise.inject.Default,javax.enterprise.inject.Any] from file:/application/webapps/ROOT/WEB-INF/classes/com/project/cache/CacheServiceImpl.class

Answer 1

基本上，你有一个继承链 C extends B extends A 并且想在不同的场景中使用 C 和 B。如果不进一步限定类就无法做到这一点，因此要么创建不同的继承方案：

interface CacheServiceBase
StandardCacheService implements CacheServiceBase
GlobalCacheService implements CacheServiceBase

// Injection of different things which do *not* extend each other
@Inject StandardCacheService
@Inject GlobalCacheService

或使用限定符注释来进一步区分实现。看这里怎么做：https://docs.jboss.org/weld/reference/latest/en-US/html/injection.html