JAVA-EE7/javax.ws.rs：在REST資源中注入EJB

Question

我試圖通過Annotation @EJB將無狀態EJB注入到我的JAX-RS web服務中。不幸的是被注射了EJB爲null，並拋出一個時被調用它的NullPointerException，請參閱類「RegistrationRest」：

@Path("/database") 
@Stateless 
public class RegistrationRest { 
    @EJB 
    private DbDao dbDao; 

    @Path("getInfo/{name}") 
    @GET 
    @Produces(MediaType.TEXT_PLAIN) 
    public String getInfoByName(@PathParam("name") String name { 
     TreeSet <String> ts = new TreeSet<String>(); 
     JsonGenerator json = new JsonGenerator().writeStartArray(); 

     // Lesen Info aus Datenbank 
     for(Persons person : dbDao.findInfoByName(name) { 
      ts.add(person.getName()); 
     } 
     // Schreiben der gefundenen Staedte in ein JSON 
     for(String name : ts) { 
      json.write(name); 
     } 
     // Rueckgabe der Daten als JSON 
     return json.writeEnd().toString(); 
    } 
} 

我的web服務註冊爲部分和通過javax.ws.rs.core.Application，看的「RestConfiguration」代碼：

package net.service.rest; 
import javax.ws.rs.ApplicationPath; 
import javax.ws.rs.core.Application; 
// other imports 

@ApplicationPath("/rest") 
public class RestConfiguration extends Application { 
    @Override 
    public Set<Class<?>> getClasses() { 
     return new HashSet<Class<?>>(Arrays.asList(RegistrationRest.class)); 
    } 
} 

由於注入的EJB實現，可能是防止EJB被注入到Web服務/資源的事實的接口，我的理解閱讀這篇文章： http://netbeans.dzone.com/articles/how-to-combine-rest-and-ejb-31

與名稱「DbDao」的EJB是實現一個接口，我想保持一個DAO：

@Stateless(name = "DbDao") 
@Local 
public class DbDaoImpl implements DbDao { 
    private final String ENTITY_MANAGER = "mouPU"; 

    @PersistenceContext(unitName = ENTITY_MANAGER) 
    protected EntityManager em; 

    @Override 
    public List<Address> findInfoByName(final String name) { 
     @SuppressWarnings("unchecked") 
     List<Person> persons = em.createNamedQuery("findInfoByName").setParameter("name", name)).getResultList(); 
     return persons; 
    } 
} 

在上面的文章中指出，無法注入其中實現一個接口的EJB 。我無法想象那是如此，或者我認爲我忽略了一些東西。

這裏是堆棧跟蹤：

16:28:14,831 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[default-host].[/].[net.Bplace.mou.ui.rest.RestConfiguration]] (http--0.0.0.0-80-6) Servlet.service() for servlet net.Bplace.mou.ui.rest.RestConfiguration threw exception: org.jboss.resteasy.spi.UnhandledException: java.lang.NullPointerException 
    at org.jboss.resteasy.core.SynchronousDispatcher.handleApplicationException(SynchronousDispatcher.java:340) [resteasy-jaxrs-2.3.2.Final.jar:] 
    at org.jboss.resteasy.core.SynchronousDispatcher.handleException(SynchronousDispatcher.java:214) [resteasy-jaxrs-2.3.2.Final.jar:] 
    at org.jboss.resteasy.core.SynchronousDispatcher.handleInvokerException(SynchronousDispatcher.java:190) [resteasy-jaxrs-2.3.2.Final.jar:] 
    at org.jboss.resteasy.core.SynchronousDispatcher.getResponse(SynchronousDispatcher.java:540) [resteasy-jaxrs-2.3.2.Final.jar:] 
    at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:502) [resteasy-jaxrs-2.3.2.Final.jar:] 
    at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:119) [resteasy-jaxrs-2.3.2.Final.jar:] 
    at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:208) [resteasy-jaxrs-2.3.2.Final.jar:] 
    at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:55) [resteasy-jaxrs-2.3.2.Final.jar:] 
    at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:50) [resteasy-jaxrs-2.3.2.Final.jar:] 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) [jboss-servlet-api_3.0_spec-1.0.0.Final.jar:1.0.0.Final] 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:329) [jbossweb-7.0.13.Final.jar:] 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:248) [jbossweb-7.0.13.Final.jar:] 
    at com.ocpsoft.pretty.PrettyFilter.doFilter(PrettyFilter.java:145) [prettyfaces-jsf2-3.3.3.jar:] 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:280) [jbossweb-7.0.13.Final.jar:] 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:248) [jbossweb-7.0.13.Final.jar:] 
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:275) [jbossweb-7.0.13.Final.jar:] 
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161) [jbossweb-7.0.13.Final.jar:] 
    at org.jboss.as.jpa.interceptor.WebNonTxEmCloserValve.invoke(WebNonTxEmCloserValve.java:50) [jboss-as-jpa-7.1.1.Final.jar:7.1.1.Final] 
    at org.jboss.as.web.security.SecurityContextAssociationValve.invoke(SecurityContextAssociationValve.java:153) [jboss-as-web-7.1.1.Final.jar:7.1.1.Final] 
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:155) [jbossweb-7.0.13.Final.jar:] 
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [jbossweb-7.0.13.Final.jar:] 
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) [jbossweb-7.0.13.Final.jar:] 
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:368) [jbossweb-7.0.13.Final.jar:] 
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877) [jbossweb-7.0.13.Final.jar:] 
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:671) [jbossweb-7.0.13.Final.jar:] 
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:930) [jbossweb-7.0.13.Final.jar:] 
    at java.lang.Thread.run(Unknown Source) [rt.jar:1.7.0_11] 
Caused by: java.lang.NullPointerException 
    at net.Bplace.mou.ui.rest.RegistrationRest.getCityByCountryAndZipCode(RegistrationRest.java:100) [classes:] 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [rt.jar:1.7.0_11] 
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) [rt.jar:1.7.0_11] 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) [rt.jar:1.7.0_11] 
    at java.lang.reflect.Method.invoke(Unknown Source) [rt.jar:1.7.0_11] 
    at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:155) [resteasy-jaxrs-2.3.2.Final.jar:] 
    at org.jboss.resteasy.core.ResourceMethod.invokeOnTarget(ResourceMethod.java:257) [resteasy-jaxrs-2.3.2.Final.jar:] 
    at org.jboss.resteasy.core.ResourceMethod.invoke(ResourceMethod.java:222) [resteasy-jaxrs-2.3.2.Final.jar:] 
    at org.jboss.resteasy.core.ResourceMethod.invoke(ResourceMethod.java:211) [resteasy-jaxrs-2.3.2.Final.jar:] 
    at org.jboss.resteasy.core.SynchronousDispatcher.getResponse(SynchronousDispatcher.java:525) [resteasy-jaxrs-2.3.2.Final.jar:] 
    ... 23 more 

你能幫忙嗎？

Answer 1

試試這個：

@ApplicationPath("/rest") 
public class RestConfiguration extends Application { 

    private Set<Class<?>> resources = new HashSet<Class<?>>(); 

    public RestConfiguration() { 
     resources.add(RegistrationRest.class); 
    } 

    @Override 
    public Set<Class<?>> getClasses() { 
     return resources; 
    } 

} 

確保您的web.xml中有這樣的：

<listener> 
    <listener-class>org.jboss.resteasy.plugins.server.servlet.ResteasyBootstrap</listener-class> 
</listener> 

最後，確保你的beans.xml在你的WEB-INF文件夾

<?xml version="1.0" encoding="UTF-8"?> 
<beans xmlns="http://java.sun.com/xml/ns/javaee" 
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
     xsi:schemaLocation=" 
     http://java.sun.com/xml/ns/javaee 
     http://java.sun.com/xml/ns/javaee/beans_1_0.xsd"> 
</beans>