NullPointerException when running CXF JAX-RS 2.0 client “target” method in Liberty Profile under a Thread

问题

I have some JAX-RS 2.0 clients running ok in Liberty Profile 8.5.5.6. They are all working ok sequentially, but I want to execute some of them in a Thread so they run concurrently. When I try to get a "target" inside a FutureTask with:

 WebTarget myResource = client.target(apiURLBase + ...);

I get NullPointerExcepton in this com.ibm.ws... class:

Caused by: java.lang.NullPointerException
     at com.ibm.ws.jaxrs20.client.bus.LibertyJAXRSClientBusFactory.getClientScopeBus(LibertyJAXRSClientBusFactory.java:89)
     at com.ibm.ws.jaxrs20.client.JAXRSClientImpl.target(JAXRSClientImpl.java:109)
     at org.apache.cxf.jaxrs.client.spec.ClientImpl.target(ClientImpl.java:100)
     at com.servengine.watson.naturallanguageclassifier.NaturalLanguageClassifierRESTClient.classify(NaturalLanguageClassifierRESTClient.java:161)
     at com.servengine.watson.naturallanguageclassifier.NaturalLanguageClassifierRESTClient$Proxy$_$$_WeldClientProxy.classify(Unknown Source)
     at com.skios.eliza.nlq.NaturalLanguageQueryFlowView$1.call(NaturalLanguageQueryFlowView.java:66)
     at com.skios.eliza.nlq.NaturalLanguageQueryFlowView$1.call(NaturalLanguageQueryFlowView.java:1)
     at java.util.concurrent.FutureTask.run(FutureTask.java:266)

CXF cannot be used out of "main" Thread? What am I missing?

Thanks for any help.

回答1:

If you want to use the client API in a forked new thread, you need to make sure the new thread is a container managed one. In your case, you can enable concurrent-1.0 feature. Then use:

@Resource(name="java:comp/DefaultManagedExecutorServcie") ManagedExecutorService executor;

 Task task = new Task();    
 Future<String> result = executor.submit(task);

In Your Task class, you can do the same thing with what you done before: WebTarget myResource = client.target(apiURLBase + ...);

来源：https://stackoverflow.com/questions/31922438/nullpointerexception-when-running-cxf-jax-rs-2-0-client-target-method-in-liber