将单例注入 JAX-RS (Jersey) 资源，作为 Tomcat servlet

Question

我正在尝试构建一个 RESTful Web 服务。该组件是对已包含多个 Servlet 的现有 Tomcat 7 Web 应用程序的补充。我使用的是 Jersey 2.25。

我需要实例化一些与现有系统相关的组件（对象）。我希望在应用程序加载时执行一次 - 然后从每个资源中读取它们。

我目前的课程是：

@ApplicationPath("resources")
public class MyApplication extends ResourceConfig {

    public MyApplication() {
        packages("plc_webservice.PersonResource");

        register(new MyBinder());
    }
}

public class MyBinder extends AbstractBinder{

    @Override
    protected void configure() {
        bind(new MyService()).to(MyService.class);
    }
}

这是我想用作单例的类：

public class MyService {
    String name;

    public MyService() {
        name = "John";
    }

    public String getName() {
        return name;
    } 
}

还有一个资源：

@Path("Person")
public class PersonResource {


    @Inject
    private MyService service;    

    @GET
    public String test() {
        String result = "Hello!";

        return result;
    }
}

我不知道为什么会出现此异常：

javax.servlet.ServletException：一个 MultiException 有 3 个异常。 他们是： 1. org.glassfish.hk2.api.UnsatisfiedDependencyException: There was no object available for injection at SystemInjecteeImpl(requiredType=MyService,parent=PersonResource,qualifiers={},position=-1,optional=false,self=false,unqualified=null,1688478701) 2. java.lang.IllegalArgumentException: 尝试解析plc_webservice.PersonResource的依赖时发现错误 3. java.lang.IllegalStateException: Unable to perform operation: resolve on plc_webservice.PersonResource

org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:489) org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427) org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388) org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341) org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393) 根本原因

一个 MultiException 有 3 个异常。他们是： 1. org.glassfish.hk2.api.UnsatisfiedDependencyException: There was no object available for injection at SystemInjecteeImpl(requiredType=MyService,parent=PersonResource,qualifiers={},position=-1,optional=false,self=false,unqualified=null,1688478701) 2. java.lang.IllegalArgumentException: 尝试解析plc_webservice.PersonResource的依赖时发现错误 3. java.lang.IllegalStateException: Unable to perform operation: resolve on plc_webservice.PersonResource

org.jvnet.hk2.internal.Collector.throwIfErrors(Collector.java:89) org.jvnet.hk2.internal.ClazzCreator.resolveAllDependencies(ClazzCreator.java:250) org.jvnet.hk2.internal.ClazzCreator.create(ClazzCreator.java:358) org.jvnet.hk2.internal.SystemDescriptor.create(SystemDescriptor.java:487) org.glassfish.jersey.process.internal.RequestScope.findOrCreate(RequestScope.java:162) org.jvnet.hk2.internal.Utilities.createService(Utilities.java:2022) org.jvnet.hk2.internal.ServiceLocatorImpl.internalGetService(ServiceLocatorImpl.java:774) org.jvnet.hk2.internal.ServiceLocatorImpl.internalGetService(ServiceLocatorImpl.java:737) org.jvnet.hk2.internal.ServiceLocatorImpl.getService(ServiceLocatorImpl.java:707) org.glassfish.jersey.internal.inject.Injections.getOrCreate(Injections.java:172) org.glassfish.jersey.server.model.MethodHandler$ClassBasedMethodHandler.getInstance(MethodHandler.java:284) org.glassfish.jersey.server.internal.routing.PushMethodHandlerRouter.apply(PushMethodHandlerRouter.java:74) org.glassfish.jersey.server.internal.routing.RoutingStage._apply(RoutingStage.java:109) org.glassfish.jersey.server.internal.routing.RoutingStage._apply(RoutingStage.java:112) org.glassfish.jersey.server.internal.routing.RoutingStage._apply(RoutingStage.java:112) org.glassfish.jersey.server.internal.routing.RoutingStage._apply(RoutingStage.java:112) org.glassfish.jersey.server.internal.routing.RoutingStage.apply(RoutingStage.java:92) org.glassfish.jersey.server.internal.routing.RoutingStage.apply(RoutingStage.java:61) org.glassfish.jersey.process.internal.Stages.process（Stages.java:197） org.glassfish.jersey.server.ServerRuntime$2.run(ServerRuntime.java:318) org.glassfish.jersey.internal.Errors$1.call(Errors.java:271) org.glassfish.jersey.internal.Errors$1.call(Errors.java:267) org.glassfish.jersey.internal.Errors.process（Errors.java:315） org.glassfish.jersey.internal.Errors.process（Errors.java:297） org.glassfish.jersey.internal.Errors.process（Errors.java:267） org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317) org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305) org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154) org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:473) org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427) org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388) org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341) org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393) 根本原因

org.glassfish.hk2.api.UnsatisfiedDependencyException: 没有 可用于注入的对象 SystemInjecteeImpl(requiredType=MyService,parent=PersonResource,qualifiers={},position=-1,optional=false,self=false,unqualified=null,1688478701) org.jvnet.hk2.internal.ThreeThirtyResolver.resolve(ThreeThirtyResolver.java: 75) org.jvnet.hk2.internal.ClazzCreator.resolve(ClazzCreator.java:212) org.jvnet.hk2.internal.ClazzCreator.resolveAllDependencies(ClazzCreator.java:235) org.jvnet.hk2.internal.ClazzCreator.create(ClazzCreator.java:358) org.jvnet.hk2.internal.SystemDescriptor.create(SystemDescriptor.java:487) org.glassfish.jersey.process.internal.RequestScope.findOrCreate(RequestScope.java:162) org.jvnet.hk2.internal.Utilities.createService(Utilities.java:2022) org.jvnet.hk2.internal.ServiceLocatorImpl.internalGetService(ServiceLocatorImpl.java:774) org.jvnet.hk2.internal.ServiceLocatorImpl.internalGetService(ServiceLocatorImpl.java:737) org.jvnet.hk2.internal.ServiceLocatorImpl.getService(ServiceLocatorImpl.java:707) org.glassfish.jersey.internal.inject.Injections.getOrCreate(Injections.java:172) org.glassfish.jersey.server.model.MethodHandler$ClassBasedMethodHandler.getInstance(MethodHandler.java:284) org.glassfish.jersey.server.internal.routing.PushMethodHandlerRouter.apply(PushMethodHandlerRouter.java:74) org.glassfish.jersey.server.internal.routing.RoutingStage._apply(RoutingStage.java:109) org.glassfish.jersey.server.internal.routing.RoutingStage._apply(RoutingStage.java:112) org.glassfish.jersey.server.internal.routing.RoutingStage._apply(RoutingStage.java:112) org.glassfish.jersey.server.internal.routing.RoutingStage._apply(RoutingStage.java:112) org.glassfish.jersey.server.internal.routing.RoutingStage.apply(RoutingStage.java:92) org.glassfish.jersey.server.internal.routing.RoutingStage.apply(RoutingStage.java:61) org.glassfish.jersey.process.internal.Stages.process（Stages.java:197） org.glassfish.jersey.server.ServerRuntime$2.run(ServerRuntime.java:318) org.glassfish.jersey.internal.Errors$1.call(Errors.java:271) org.glassfish.jersey.internal.Errors$1.call(Errors.java:267) org.glassfish.jersey.internal.Errors.process（Errors.java:315） org.glassfish.jersey.internal.Errors.process（Errors.java:297） org.glassfish.jersey.internal.Errors.process（Errors.java:267） org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317) org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305) org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154) org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:473) org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427) org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388) org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341) org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)

谢谢。

Answer 1

首先注入的资源（bean）和 Jersey 端点类（注入点）必须是 CDI 感知的。它必须能够被 CDI 检测到。我们可以使用 bean-discovery-mode="all" - 然后 CDI 扫描所有类或 bean-discovery-mode="annotated" 并用正确的注释标记我们的类：从这里：Bean defining annotations。我更喜欢@Dependent 或@RequestScoped

那么我们必须使用 Jersey Extension

<dependency>
  <groupId>org.glassfish.jersey.ext.cdi</groupId>
  <artifactId>jersey-cdi1x-servlet</artifactId>
  <version>{version}</version>
  <scope>runtime</scope>
</dependency>

`

将 CDI 与 HK2 发现机制连接起来。 这里是Official oracle Guideline

Answer 2

我认为这是一个 CDI 问题。你定义了 beans.xml 吗？另外，如果您希望MyService 成为单例，我想您想用@ApplicationScoped 对其进行注释。