吉斯地图绑定器

Question

我在Java + Kotlin项目中使用Guice将算法实现的映射注入到特定的bean中，但我不断得到

1) No implementation for java.util.Map<java.lang.String, ? extends com.scherule.scheduling.algorithms.SchedulingAlgorithm> annotated with @com.google.inject.name.Named(value=scheduling.algorithms) was bound.
while locating java.util.Map<java.lang.String, ? extends com.scherule.scheduling.algorithms.SchedulingAlgorithm> annotated with @com.google.inject.name.Named(value=scheduling.algorithms)
for the 2nd parameter of com.scherule.scheduling.SchedulingJobConsumer.<init>(SchedulingJobConsumer.kt:17)
while locating com.scherule.scheduling.SchedulingJobConsumer

模块的定义如下：

class AlgorithmsModule : AbstractModule() {
override fun configure() {
MapBinder.newMapBinder(binder(),
String::class.java,
SchedulingAlgorithm::class.java,
Names.named("scheduling.algorithms")
).addBinding("interval-projection").toInstance(IntervalProjectionAlgorithm())
}
}

调用方代码是：

@Singleton
class SchedulingJobConsumer
@Inject constructor(
@Named("scheduling.channel") channel: Channel,
@Named("scheduling.algorithms") val schedulers: Map<String, SchedulingAlgorithm>
) : DefaultConsumer(channel) ...

但是当我这样做时

injector.getInstance(Key.get(new TypeLiteral<Map<String, SchedulingAlgorithm>>() {}, named("scheduling.algorithms")))

它就在那里。怎么了？

Answer 1

问题在于 Kotlin 泛型 ！= Java 泛型。

这个 Kotlin 代码。

@Named("scheduling.algorithms") val schedulers: Map<String, SchedulingAlgorithm>

编译为

Map<String, ? extends SchedulingAlgorithm> and not Map<String, SchedulingAlgorithm>

注入Guice时，正在寻找没有绑定Map<String, ? extends SchedulingAlgorithm>，因为MapBinder为Map<String, SchedulingAlgorithm>创建了绑定。

Answer 2

您可以尝试将以下成员方法添加到AlgorithmsModule中，而不是使用MapBinder：

@Provides
@Singleton
@Named("scheduling.algorithms")
fun schedulingAlgorithms(): Map<String, @JvmSuppressWildcards SchedulingAlgorithm> {
return IntervalProjectionAlgorithm()
}