Question

我希望你能帮助我：我有一个使用Eclipse创建的WebProject作为动态Web项目，在Glassfish3服务器上运行。我正在使用EJB 3.0创建一个实现我的业务逻辑的无状态Façade（@stateless Annotation）：

@Stateless
public class Facade {   

public void test(){     
System.out.println("test hat geklappt!!");
}   
}

此外，我正在使用RESTRessource来提供我的REST WS，它使用我的EJB（@EJB Annotation）业务逻辑：

@RequestScoped
@Path("/prescriptions")
public class Ressource {

    @EJB
    private Facade facade;

    public Ressource() {
        super();
    }

    @GET
    @Path("/user/{userid}")
    @Produces(MediaType.APPLICATION_JSON)
    public void getUser(@PathParam("userid") String userid) {

        facade.test();

    }   

}

虽然我可以进入REST WS并调用它，但我的EJB总是为空，我找不到原因。

如果你能帮助我，我真的很感激。如果您需要有关代码的更多信息，或者只是询问。

提前致谢，弗洛里安

PS：我的日志中总是出现以下错误：

INFO: Portable JNDI names for EJB Facade : [java:global/TestProject/Facade,java:global/TestProject/Facade!webservices.Facade]   
INFO: Portable JNDI names for EJB Facade : [java:global/TestProject/Facade, java:global/TestProject/Facade!webservices.Facade]
INFO: Scanning for root resource and provider classes in the packages:
webservices
INFO: Root resource classes found:
class webservices.Ressource
INFO: No provider classes found.
INFO: Initiating Jersey application, version 'Jersey: 1.5 01/14/2011 12:36 PM'

SCHWERWIEGEND: The RuntimeException could not be mapped to a response, re-throwing to the HTTP container    
java.lang.NullPointerException

at webservices.Ressource.getUser(Ressource.java:40)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$VoidOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:150)
at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:70)
at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:279)
at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:136)
at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:86)
at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:136)
at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:74)
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1347)
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1279)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1229)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1219)
at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:419)
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:537)
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:699)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:848)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1534)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98)
at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:162)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:326)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:227)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:170)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:822)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:719)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1013)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:662)

Answer 1

理想情况下，RESTFul类设计应为stateless，如article中所述：

无国籍服务不仅表现更好，而且大部分时间都在转移将状态维护到客户端应用程序的责任

如果将Stateless注释添加到Ressource类，则可以注入Facade会话bean，容器将关注会话bean的生命周期。

这将使您的代码顺利运行，没有例外。

不要忘记让你的getUser方法返回一个值！

    public String getUser(@PathParam("userid") String userid) {

        facade.test();

        return "{" + userid + "}";
    }

EJB3无状态Bean在REST-WebService（Glassfish3，EJB3，Stateless Bean，）中始终为null

1 个答案: