Liferay 7.1.2中JSF Bean @Reference注入OSGI服务为空问题求助

Let's break down exactly what's going wrong here and how to fix it.

The Core Issue: Conflicting Instance Managers #

Your RegisterSearchBean is annotated with both @ManagedBean (managed by the JSF container) and @Component (managed by the OSGi container). This creates two separate instances of the bean:

• The JSF container creates an instance for your view, but this instance never goes through OSGi's dependency injection process—so the @Reference annotation is completely ignored, leaving _applicationServices null.
• The OSGi container creates another instance that does get the service injected, but this isn't the instance your JSF page is actually using.

Fix 1: Switch to CDI Beans (Recommended for Liferay 7.x) #

Liferay's OSGi integration works seamlessly with CDI, so replacing the JSF @ManagedBean with CDI's @Named lets OSGi handle both bean management and dependency injection properly. Here's the revised code:

@Named("registerSearchBean")
@ViewScoped
@Component(
    immediate = true,
    service = RegisterSearchBean.class
)
public class RegisterSearchBean implements Serializable {
    public String message;

    @Reference
    private ApplicationServices _applicationServices;

    @PostConstruct
    public void initBean(){
        getSearchFiltersForRegister();
    }

    public void getSearchFiltersForRegister(){
        message = _applicationServices.getSearchFiltersForRegister("asd");
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }
}

Key Changes: #

1. Replaced @ManagedBean with @Named (CDI's standard bean annotation)
2. Updated the @Component's service property to explicitly reference the bean class (avoids generic type issues)
3. Added Serializable (required for @ViewScoped beans)

Fix 2: Manually Fetch OSGi Service (If You Must Keep @ManagedBean) #

If you need to stick with the JSF managed bean pattern, you can manually look up the OSGi service instead of relying on @Reference. Just be sure to clean up the service reference when the bean is destroyed:

@ManagedBean(name = "registerSearchBean")
@ViewScoped
public class RegisterSearchBean implements Serializable {
    public String message;
    private ApplicationServices _applicationServices;
    private ServiceReference<ApplicationServices> _serviceRef;

    @PostConstruct
    public void initBean(){
        BundleContext bundleContext = FrameworkUtil.getBundle(RegisterSearchBean.class).getBundleContext();
        _serviceRef = bundleContext.getServiceReference(ApplicationServices.class);
        
        if (_serviceRef != null) {
            _applicationServices = bundleContext.getService(_serviceRef);
        }

        getSearchFiltersForRegister();
    }

    public void getSearchFiltersForRegister(){
        if (_applicationServices != null) {
            message = _applicationServices.getSearchFiltersForRegister("asd");
        } else {
            message = "Service unavailable";
        }
    }

    @PreDestroy
    public void cleanup(){
        BundleContext bundleContext = FrameworkUtil.getBundle(RegisterSearchBean.class).getBundleContext();
        if (_serviceRef != null) {
            bundleContext.ungetService(_serviceRef);
        }
    }

    // Getters and setters remain the same
}

Important Notes for This Approach: #

• Add OSGi Core API dependency to your JSF module's build.gradle:

  dependencies {
      compileOnly group: 'org.osgi', name: 'osgi.core', version: '6.0.0'
  }
  

• This requires manual service lifecycle management, which is error-prone—stick with Fix 1 if possible.

Quick Validation Checks #

Before testing your fix, verify these basics:

1. Run lb in Liferay's Gogo Shell to confirm your API and service provider modules are in Active state.
2. Run service:list ApplicationServices to ensure your service is registered in the OSGi registry.
3. Double-check your JSF module's build.gradle includes a compile-only dependency on your API module.

内容的提问来源于stack exchange，提问作者Georgi D.