Question

我跟踪数据库中consumerId的服务提供商列表。

我有SchedulerActor为TaskActor启用的每个服务提供商创建consumerId。

我想为列表中的每个服务提供商注入ServiceProvider到TaskActor的实现。 ServiceProvider可以有不同的实现。

interface ServiceProvider {
    void processRequest(Request request);
}

class SchedulerActor {
     @Override
     public void onReceive(Object consumerId) throws Exception {
         List<String> serviceProvidersList = getFromDatabase((String) consumerId);
         for (String serviceProviderStr : serviceProvidersList) {

              //serviceProviderStr could be "ServiceProvider1" or "ServiceProvider2" 
              ServiceProvider serviceProvider = getServiceProviderFromStr(serviceProviderStr); 

              ActorRef r = getContext().actorOf(Props.create(TaskActor.class, serviceProvider));
              getContext().watch(r);
              routees.add(new ActorRefRoutee(r));

         }
         router = new Router(new BroadcastRoutingLogic(), routees);
         router.route(message, getSelf());
     }
}

class TaskActor {
    private final ServiceProvider serviceProvider;
    public TaskActor(ServiceProvider serviceProvider) {
        this.serviceProvider = serviceProvider;
    }

    @Override
    public void onReceive(Object message) {
        if (message instanceof Request) {
            serviceProvider.processRequest((Request)message);
        }
    }
}

getServiceProviderFromStr(String)内部有什么来实现这个目标？
我不想添加switch或if else语句来返回所需的实现。
我可以在运行时提供Provider Bindings，将字符串传递给提供者对象吗？

Answer 1

使用Guice AssistedInject，即FactoryModuleBuilder向TaskActor构造函数添加服务名称的String参数，并使用此参数注入带有@Named注释的ServiceProvider：

在模块中定义工厂界面：

public interface TaskActorFactory{
    TaskActor create(String serviceName);
}

在模块 configure 方法中安装工厂并注册服务绑定：

protected void configure() {
    bind(ServiceProvider.class).annotatedWith(Names.named("serviceA")).to(ServiceA.class);
    bind(ServiceProvider.class).annotatedWith(Names.named("serviceB")).to(ServiceB.class);
    bind(ServiceProvider.class).annotatedWith(Names.named("serviceC")).to(ServiceC.class);
    install(new FactoryModuleBuilder()
        .implement(TaskActor.class, TaskActor.class)
        .build(TaskActorFactory.class));
 }

实施TaskActor：

@Inject 
class TaskActor extends UntypedActor {

    public static Props props(String serviceName) {
        return Props.create(TaskActor.class, ()->new TaskActor(serviceName));
    }

    private final ServiceProvider serviceProvider;

    public TaskActor(Injector injector, @Assisted String serviceName) {
        serviceProvider = injector.getInstance(Key.get(ServiceProvider.class, Names.named(serviceName)));
    }
    ...
}

从SchedulerActor创建TaskActor

@Override
public void onReceive(Object consumerId) throws Exception {
     List<String> serviceProvidersList = getFromDatabase((String) consumerId);
     for (String serviceProviderStr : serviceProvidersList) {
         ActorRef r = getContext().actorOf(TaskActor.props(serviceProviderStr));
         getContext().watch(r);
         routees.add(new ActorRefRoutee(r));
     }
     ...
 }

}

Answer 2

使用相同命名绑定而不是建议@Assisted

的另一种方法

@Inject 
public Injector injector;
...
ServiceProvider s = injector.getInstance(Key.get(Parent.class, Names.named(serviceName)));

其中绑定在configure（）中的类：

bind(ServiceProvider.class).annotatedWith(Names.named("Name1")).to(Child1.class);
bind(ServiceProvider.class).annotatedWith(Names.named("Name2")).to(Child2.class);

Answer 3

如果您不想使用pydev_file_utils.pyc switch，我认为您必须使用反射来执行此操作，其中if else是类名。

serviceProviderStr

请记住，您可以通过调用private ServiceProvider getServiceProviderFromStr(String serviceProviderClassName){ try { Class<?> clazz = Class.forName(serviceProviderClassName); if(!ServiceProvider.class.isAssignableFrom(clazz)){ throw new IllegalArgumentException("Argument is not a ServiceProvider class."); } Class<? extends ServiceProvider> serviceProviderClass = (Class<? extends ServiceProvider>) clazz; return serviceProviderClass.newInstance(); } catch (ClassNotFoundException | InstantiationException | IllegalAccessException e) { e.printStackTrace(); } return null; }来获取课程名称。

根据Play框架

3 个答案: