带有@PersistenceContext的EntityManager的NPE

Question

我现在已经坚持了几天。它是关于在Wildfly10上使用EJB和Hibernate的REST服务。注入@ PersistenceContext后，EntityManager始终为null。我会非常开心我有人可以告诉我我做错了什么。提前谢谢！

电贺 约什

这是我的代码：

User.java

package de.oosting.findpeople.userservice;

import javax.persistence.*;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import javax.xml.bind.annotation.XmlRootElement;

@Entity
@XmlRootElement
public class User implements java.io.Serializable {
private static final long serialVersionUID = -6091824661950209090L;
/** Primary key */
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
protected int uid;
@NotNull(message="Name required")
@Size(min=1, message="Name required")
protected String name;
protected String address;

public int getUid() {
    return this.uid;
}

public void setUid(int uid) {
    this.uid = uid;
}
public String getName() {
    return this.name;
}

public void setName(String name) {
    this.name = name;
}

public String getAddress() {
    return this.address;
}

public void setAddress(String address) {
    this.address = address;
}

@Override
public String toString() {
    return getName() + " (UID=" + getUid() + (getAddress()!=null?", "+getAddress():"") + ")";
}
}

UserDao.java

package de.oosting.findpeople.userservice;
import java.util.List;

import javax.ejb.LocalBean;
import javax.ejb.Stateless;
import javax.ejb.TransactionAttribute;
import javax.ejb.TransactionAttributeType;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

@Stateless
@LocalBean
public class UserDao { 
   @PersistenceContext(unitName = "FindPeople-Persistence")
    private EntityManager em;

    public User getUser(int id) {
        return em.find(User.class, id);
    }

    @TransactionAttribute(TransactionAttributeType.REQUIRED)
    public void addUsers(List<User> users) {
        for (User user : users) {
            em.persist(user);
        }
    }
}

UserService.java

package de.oosting.findpeople.userservice;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.ejb.EJB;
import javax.ejb.LocalBean;
import javax.ejb.Stateless;
import javax.ws.rs.Consumes; 
import javax.ws.rs.FormParam; 
import javax.ws.rs.GET; 
import javax.ws.rs.OPTIONS; 
import javax.ws.rs.PUT; 
import javax.ws.rs.Path; 
import javax.ws.rs.PathParam; 
import javax.ws.rs.Produces; 
import javax.ws.rs.core.MediaType;

import de.oosting.findpeople.userservice.UserDao;
@Path("/UserService") 
@Stateless
@LocalBean
public class UserService { 
@EJB
private UserDao userDAO;

private static final String SUCCESS_RESULT = "<result>success</result>"; 
private static final String FAILURE_RESULT = "<result>failure</result>";  

@GET 
@Path("/users/{userid}") 
@Produces(MediaType.APPLICATION_XML) 
public User getUser(@PathParam("userid") int userid){ 
  return userDAO.getUser(userid); 
}  
@PUT 
@Path("/users") 
@Produces(MediaType.APPLICATION_XML) 
@Consumes(MediaType.APPLICATION_FORM_URLENCODED)
public String createUser(@FormParam("id") int id, 
  @FormParam("name") String name, 
  @FormParam("address") String address) throws IOException{ 

  User newUser = new User();
  newUser.setName(name);
  newUser.setAddress(address);

  List<User> users = new ArrayList<User>();
  users.add(newUser);

  userDAO.addUsers(users);

  return SUCCESS_RESULT; 
}  

@OPTIONS 
@Path("/users") 
@Produces(MediaType.APPLICATION_XML) 
public String getSupportedOperations(){ 
  return "<operations>GET, PUT, POST, DELETE</operations>"; 
} 
}

的persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
<persistence-unit name="FindPeople-Persistence">
<provider>org.hibernate.ejb.HibernatePersistence</provider>

  <jta-data-source>java:jboss/MissingPeopleDS</jta-data-source>
  <class>de.oosting.findpeople.userservice.User</class>
  <properties>
  <property name="hibernate.transaction.jta.platform" value="org.hibernate.service.jta.platform.internal.JBossAppServerJtaPlatform" />

     <property name="hibernate.hbm2ddl.auto" value="create-drop" />
     <property name="hibernate.archive.autodetection" value="class" />
     <property name="hibernate.format_sql" value="true" />
     <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
     <property name="hibernate.show_sql" value="true" />
  </properties>
</persistence-unit>
</persistence>

异常

17:09:43,339 ERROR [io.undertow.request] (default task-2) UT005023: Exception handling request to /UserService/rest/UserService/users: org.jboss.resteasy.spi.UnhandledException: java.lang.NullPointerException
at org.jboss.resteasy.core.ExceptionHandler.handleApplicationException(ExceptionHandler.java:77)
at org.jboss.resteasy.core.ExceptionHandler.handleException(ExceptionHandler.java:220)
at org.jboss.resteasy.core.SynchronousDispatcher.writeException(SynchronousDispatcher.java:175)
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:418)
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:209)
at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:221)
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:56)
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:51)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)
at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:131)
at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)
at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)
at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:60)
at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:77)
at io.undertow.security.handlers.NotificationReceiverHandler.handleRequest(NotificationReceiverHandler.java:50)
at io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:292)
at io.undertow.servlet.handlers.ServletInitialHandler.access$100(ServletInitialHandler.java:81)
at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:138)
at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:135)
at io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:48)
at io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43)
at io.undertow.servlet.api.LegacyThreadSetupActionWrapper$1.call(LegacyThreadSetupActionWrapper.java:44)
at io.undertow.servlet.api.LegacyThreadSetupActionWrapper$1.call(LegacyThreadSetupActionWrapper.java:44)
at io.undertow.servlet.api.LegacyThreadSetupActionWrapper$1.call(LegacyThreadSetupActionWrapper.java:44)
at io.undertow.servlet.api.LegacyThreadSetupActionWrapper$1.call(LegacyThreadSetupActionWrapper.java:44)
at io.undertow.servlet.api.LegacyThreadSetupActionWrapper$1.call(LegacyThreadSetupActionWrapper.java:44)
at io.undertow.servlet.api.LegacyThreadSetupActionWrapper$1.call(LegacyThreadSetupActionWrapper.java:44)
at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:272)
at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:81)
at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:104)
at io.undertow.server.Connectors.executeRootHandler(Connectors.java:202)
at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:805)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
at de.oosting.findpeople.userservice.UserService.createUser(UserService.java:55)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:139)
at org.jboss.resteasy.core.ResourceMethodInvoker.invokeOnTarget(ResourceMethodInvoker.java:295)
at org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:249)
at org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:236)
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:402)
... 43 more