JavaHK2：使用立即作用域绑定到接口的实现

Question

我正在构建一个将在Jetty服务器上运行的应用程序。我的主类从ResourceConfig扩展到启动“javax.ws.rs.Application”，init参数设置为此类。我还使用ServiceLocator按需返回服务实例；还使用AbstractBinder将类与Singleton&；直接作用域

我的与依赖项注入相关的ResourceConfig类代码如下所示：

public class MyServer extends ResourceConfig {

    @Inject
    public MyServer() {
      packages("My.REST");
    }

    public static void main(String[] args) {

    final Server server = new Server(MythreadPool);

    HttpConfiguration httpConfig = new HttpConfiguration();
    httpConfig.addCustomizer(new ForwardedRequestCustomizer());
    ServerConnector connector = new ServerConnector(server, new HttpConnectionFactory(httpConfig));

    //Code for connector porperties
    server.addConnector(connector);
    ContextHandlerCollection contexts = new ContextHandlerCollection();
    server.setHandler(contexts);

    final WebAppContext webApp = setupWebAppContext(contexts, conf);


    ServiceLocator serviceLocator = ServiceLocatorFactory.getInstance().create("my-locator");
    ServiceLocatorUtilities.enableImmediateScope(serviceLocator);
        ServiceLocatorUtilities.bind(
        sharedServiceLocator,
        new AbstractBinder() {
          @Override
          protected void configure() {
            bind(ClassA.class).to(InterfaceService.class).in(Immediate.class);
          }
         });
    }

    webApp.addEventListener(
        new ServletContextListener() {
          @Override
          public void contextInitialized(ServletContextEvent servletContextEvent) {
            servletContextEvent
                .getServletContext()
                .setAttribute(ServletProperties.SERVICE_LOCATOR, serviceLocator);
          }

          @Override
          public void contextDestroyed(ServletContextEvent servletContextEvent) {}
        });

    setupRestApiContextHandler(webApp, conf);

    try {
        server.start();
    } catch (Exception e) {
        LOG.error("Error while running jettyServer", e);
        System.exit(-1);
    }
}

private static WebAppContext setupWebAppContext(ContextHandlerCollection contexts, Configuration conf) {
    WebAppContext webApp = new WebAppContext();
    webApp.setContextPath(conf.getServerContextPath());
    webApp.addServlet(new ServletHolder(new DefaultServlet()), "/*");
    contexts.addHandler(webApp);

    webApp.addFilter(new FilterHolder(MyFilter.class), "/*", EnumSet.allOf(DispatcherType.class));
    webApp.setInitParameter("org.eclipse.jetty.servlet.Default.dirAllowed","true");

    return webApp;
}

private static void setupRestApiContextHandler(WebAppContext webapp, Configuration conf) {
    final ServletHolder servletHolder =
        new ServletHolder(new org.glassfish.jersey.servlet.ServletContainer());

    servletHolder.setInitParameter("javax.ws.rs.Application", MyServer.class.getName());
    servletHolder.setName("rest");
    servletHolder.setForcedPath("rest");
    webapp.setSessionHandler(new SessionHandler());
    webapp.addServlet(servletHolder, "/api/*");

    webapp.setInitParameter("shiroConfigLocations", "ShiroFilePathURI");
      webapp
          .addFilter(ShiroFilter.class, "/MyRestApiPath/*", EnumSet.allOf(DispatcherType.class))
          .setInitParameter("staticSecurityManagerEnabled", "true");
      webapp.addEventListener(new EnvironmentLoaderListener());
    }
  }

我的ClassA看起来像这样：

public class ClassA implements InterfaceService {
    @Inject
    public ClassA(SomeClass instances){
     //initialize some variable
    }
}

有一个注入InterfaceService的REST类：

@Path("/my_rest")
@Produces("application/json")
@Singleton
public class RestApi {

  private InterfaceService interfaceService;

  @Inject
  public RestApi(InterfaceService interfaceService) {
    this.interfaceService = interfaceService;
  }
}

运行此代码时，会出现以下异常：

"javax.servlet.ServletException: A MultiException has 4 exceptions. They are: 1. java.lang.IllegalStateException: Could not find an active context for org.glassfish.hk2.api.Immediate 2. java.lang.IllegalStateException: While attempting to create a service for SystemDescriptor( implementation=ClassA contracts={InterfaceService}"

• 在MyServer类中，当我将类与Singleton作用域绑定时，它会按预期工作。即 bind(ClassA.class).to(InterfaceService.class).in(Singleton.class);

• 然后，如果我将RestApi类更新为以下

@Path("/my_rest")
@Produces("application/json")
@Singleton
public class RestApi {

  private ClassA classA;

  @Inject
  public RestApi(ClassA classA) {
    this.classA = classA;
  }
}

然后一切都按预期进行，范围也很近

对我来说，将作用域更改为Immediate是必需的，因为我需要在服务器启动时在类中执行某些操作。另外，我不能在RestApi中使用ClassA的引用，因为将来会有InterfaceService接口的其他实现，所以我需要在RestApi中对接口进行编码。 关于我需要做什么才能让代码在立即作用域中工作，并将其绑定到InterfaceService的任何线索