我在服务器的字段注入上获得空指针异常,该服务器作为akka actor启动.
计划部分：
private ActorRef myActor = Akka.system().actorOf(
new Props(Retreiver.class));
@Override
public void onStart(Application app) {
log.info("Starting schedular.....!");
Akka.system()
.scheduler()
.schedule(Duration.create(0,TimeUnit.MILLISECONDS),Duration.create(30,TimeUnit.MINUTES),myActor,"tick",Akka.system().dispatcher());
}
Retreiver类部分：
public class Retreiver extends UntypedActor {
private Logger.ALogger log = Logger.of(Retreiver .class);
@Inject
private myDataService dataService;
@Override
public void onReceive(Object arg0) throws Exception {
if (0 != dataService.getDataCount()) {
....
....
....
}
}
我为dataService获取null.请就此向我提出建议.
谢谢.
解决方法
你得到了NullPointerException,因为Akka正在实例化你的猎犬演员,而不是Guice.您需要让Guice构建您的实例,然后将其传递给Akka,
IndirectActorProducer可以帮助您实现此目的,例如：
class RetrieverDependencyInjector implements IndirectActorProducer {
final Injector injector;
public RetrieverDependencyInjector(Injector injector) {
this.injector = injector;
}
@Override
public Class<? extends Actor> actorClass() {
return Retriever.class;
}
@Override
public Retriever produce() {
return injector.getInstance(Retriever.class);
}
}
请注意,generate()必须在每次调用时创建一个新的Actor实例,它不能返回相同的实例.
然后你可以让Akka通过RetrieverDependencyInjector检索你的actor,例如：
ActorRef myActor = Akka.system().actorOf(
Props.create(RetrieverDependencyInjector.class,injector)
);
UPDATE
我想你进一步评论,你可以通过提供你想要的Actor作为构造函数参数的类来将RetrieverDependencyInjector变成GenericDependencyInjector,这可能允许你做类似的事情：
Props.create(GenericDependencyInjector.class,injector,Retriever.class)
我没试过这个,但它可能会给你一个起点.
