如何使HK2 ServiceLocator使用来自它桥接的ServiceLocator的Singleton服务实例？

问题描述

我们正在使用 ExtrasUtilities.bridgeServiceLocator（）通过将应用ServiceLocator桥接到Jersey ServiceLocator，将在一个ServiceLocator中创建的现有Singleton应用服务注入到Jersey RESTful Web服务中。

We are using using ExtrasUtilities.bridgeServiceLocator() to inject existing Singleton application services created in one ServiceLocator into Jersey RESTful Web Services by bridging the app ServiceLocator into the Jersey ServiceLocator.

然而，外部定位器中存在的单身人士没有被使用 - 当注入泽西服务时，每个服务都会被再次创建。似乎Singleton只在ServiceLocator的范围内可见，即使它已被桥接。

However the Singletons that exist in the 'outer' locator aren't being used - each of the services is being created once again when injected into the Jersey services. It seems the Singleton is only visible within the scope of a ServiceLocator, even if it's bridged.

这是预期的行为吗？如果是这样，是否有任何方法可以改变这种行为并在桥接的ServiceLocators中拥有一个真正的Singleton？

Is this the intended behaviour? And if so is there any way to change this behaviour and have a true Singleton across bridged ServiceLocators?

我已将问题提取到一组测试类中，以说明点下面：

I have extracted the issue out into a set of test classes that illustrate the point below:

public class BridgedServiceTest
{
  private ServiceLocator _outerServiceLocator;
  private ServiceLocator _innerServiceLocator;

  @Test
  public void testBridgedInnerServiceOK() throws Exception
  {
    ServiceLocatorFactory serviceLocatorFactory = ServiceLocatorFactory.getInstance();

    _outerServiceLocator = serviceLocatorFactory.create("Outer");
    ServiceLocatorUtilities.addClasses(_outerServiceLocator, SingletonServiceImpl.class);

    _innerServiceLocator = serviceLocatorFactory.create("Inner");
    ExtrasUtilities.bridgeServiceLocator(_innerServiceLocator, _outerServiceLocator);

    final Client client1 = new Client();
    _outerServiceLocator.inject(client1);
    assertThat(SingletonServiceImpl.instanceCount.get(), Matchers.is(1));
    client1.test();

    final Client client2 = new Client();
    _innerServiceLocator.inject(client2);
    // next line fails as instance count is 2
    assertThat(SingletonServiceImpl.instanceCount.get(), Matchers.is(1));
    client2.test();
  }

  @After
  public void tearDown() throws Exception
  {
    _innerServiceLocator.shutdown();
    _outerServiceLocator.shutdown();
  }
}

@Contract
public interface SingletonService
{
  void fulfil();
}

@Service
public class SingletonServiceImpl implements SingletonService
{
  public static AtomicInteger instanceCount = new AtomicInteger();

  @PostConstruct
  public void postConstruct()
  {
    instanceCount.incrementAndGet();
  }

  @Override
  public void fulfil()
  {
    System.out.println("Contract Fulfilled.");
  }
}

public class Client
{
  @Inject
  private SingletonService _singletonService;

  public void test()
  {
    _singletonService.fulfil();
  }

  public SingletonService getSingletonService()
  {
    return _singletonService;
  }
}

推荐答案

那里是ServiceLocator桥中的一个已修复的错误。修复将在hk2 2.5.0-b07或更高版本中！

There was a bug in the ServiceLocator bridge which has been fixed. The fix will be in hk2 2.5.0-b07 or later!

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