OSGI DS @Reference 中的原子引用

Question

我正在编写一个包含动态和静态引用的 OSGI 应用程序。每个服务都放在不同的包中。

@Reference (bind = "bindMethod", unbind = "unbindMethod", cardinality = ReferenceCardinality.MANDATORY_UNARY, policy = ReferencePolicy.DYNAMIC)
    private final AtomicReference<TestService> testService = new AtomicReference<TestService>();

@Reference (bind = "bindMethod", unbind = "unbindMethod", cardinality = ReferenceCardinality.MANDATORY_UNARY, policy = ReferencePolicy.DYNAMIC)
    private AtomicReference<TestService> testService = new AtomicReference<TestService>(); //final is ommitted

 protected void bindMethod(TestService atestService)
    {
        if (TestService.get() == null)
        {
            testService.set(atestService);
        }
    }

    protected void unbindMethod(TestService atestService)
    {
        myServices.compareAndSet(testService, null);
    }

没有原子引用

@Reference (bind = "bindMethod", unbind = "unbindMethod", cardinality = ReferenceCardinality.MANDATORY_UNARY, policy = ReferencePolicy.DYNAMIC)
    private TestService testService;

protected void bindMethod(TestService atestService)
    {
        testService = atestService;
    }

    protected void unbindMethod(TestService atestService)
    {
        testService = null;
    }

推荐哪一种，每一种对性能的影响是什么？

Answer 1

您将@Reference 放在字段上的事实意味着您正在使用具有新字段注入支持的 DS 1.3。

在这种情况下，您不需要绑定/取消绑定方法，也不需要 AtomicReference。只是：

@Reference private volatile TestService testService;

volatile 表示它是一个动态引用，并且还提供适当的并发访问。