如何使用声明式服务来确保 EventAdmin 不为空？

Question

我是 OSGi 的新手，我尝试使用 DS 创建一个简单的 EventPublisher/-Admin 应用程序以确保 EventAdmin 不为空。但我不确定如何以正确的方式使用 DS。

Activator类：

package publishertest;

import java.util.HashMap;

import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.service.component.annotations.Reference;
import org.osgi.service.event.Event;
import org.osgi.service.event.EventAdmin;

public class Activator implements BundleActivator {

    private static BundleContext context;
    
    @Reference
    EventAdmin eventAdmin;

    static BundleContext getContext() {
        return context;
    }

    public void start(BundleContext bundleContext) throws Exception {
        Activator.context = bundleContext;
        Event event = new Event("test", new HashMap<String, Object>());
        eventAdmin.postEvent(event);
        System.out.println("event posted");
    }

    public void stop(BundleContext bundleContext) throws Exception {
        Activator.context = null;
    }

}

EventHandler类：

package publishertest;

import org.osgi.service.component.annotations.Component;
import org.osgi.service.event.Event;
import org.osgi.service.event.EventHandler;

@Component(
    property = {
        "event.topics=org/osgi/framework/BundleEvent/STARTED,test"
    }
)


public class ServiceComponent implements EventHandler {

    public void handleEvent(Event event) {
        System.out.println(event.getTopic());
    }

}

添加 @Reference 注释会导致 BundleException。有人可以帮忙吗？谢谢:)