Json ClassCastException com.sun.org.apache.xerces.internal.dom.ElementNSImpl

我得到一个ClassCastException。我不知道我在这里做错了什么。执行

（RegistrationRequest）（element.getValue（））

应该可以工作。我知道

（RegistrationRequest）元素.getValue（）

可能没有

SEVERE: Servlet.service() for servlet [Jersey REST Service] in context with path [/mCruiseOnCarPool4All] threw exception
java.lang.ClassCastException: com.sun.org.apache.xerces.internal.dom.ElementNSImpl cannot be cast to com.mcruiseon.common.message.request.RegistrationRequest

请注意方法签名中的JAXBElement。我正在输入它

clientSession.waitAndGetResponse（（RegistrationRequest）（element.getValue（））。这是我得到异常的行号

@POST
@Path ("Request")
@Consumes({ MediaType.APPLICATION_JSON })
public Response post(JAXBElement<Object> element) {
    AMessageStrategy response ;
    try {
        clientSession = new ClientSession(God.mCruiseOnServer) ;
    } catch (InvalidServerDNSorIPException e) {
        e.printStackTrace();
        return Response.serverError().build() ;
    }
    sessionKey = sessionManager.setClientSession(clientSession) ;
    clientSession.setSessionKey(sessionKey) ;

    clientSession.getSendQueue().sendRequest((RegistrationRequest)(element.getValue()));                
    try {
        response = clientSession.waitAndGetResponse((RegistrationRequest)(element.getValue())) ;
    } catch (WaitedLongEnoughException e) {
        return Response.serverError().build() ;
    } catch (UnableToResolveResponseException e) {
        return Response.serverError().build() ;
    }   
    return Response.ok(response).build();
}

问题出在客户端junit测试用例上。我没有使用register为创建Json对象，而是使用clientIdentity创建对象。请注意
writeValueAsString
。我还修改了我的整个客户端，以实际使用JSON客户端API，而不是传统的http。还没开始工作，我又遇到了一个例外。但这是另一个问题

ClientConfig config = new DefaultClientConfig();
        Client client = Client.create(config);
        WebResource service = client.resource(UriBuilder.fromUri(
                "http://localhost:8081/mCruiseOnCarPool4All").build());

        ClientIdentityConcrete clientIdentity = new ClientIdentityConcrete("username", "password", "secretkey");
        RegistrationRequest register = new RegistrationRequest(clientIdentity);
        AMessageStrategy response = service.path("carpool4all").path("Registration").path("Request")
                .type(MediaType.APPLICATION_JSON).post(RegistrationRequest.class, register);
        assertNotNull(response) ;
        assertNotNull(((RegistrationResponse)response).getIdentityHash()) ;

ClientConfig config = new DefaultClientConfig();
        Client client = Client.create(config);
        WebResource service = client.resource(UriBuilder.fromUri(
                "http://localhost:8081/mCruiseOnCarPool4All").build());

        ClientIdentityConcrete clientIdentity = new ClientIdentityConcrete("username", "password", "secretkey");
        RegistrationRequest register = new RegistrationRequest(clientIdentity);
        AMessageStrategy response = service.path("carpool4all").path("Registration").path("Request")
                .type(MediaType.APPLICATION_JSON).post(RegistrationRequest.class, register);
        assertNotNull(response) ;
        assertNotNull(((RegistrationResponse)response).getIdentityHash()) ;