JPA 实体管理器未正确注入 - Weblogic

Question

我有一个 EAR 应用程序（部署在 Weblogic 12c 上），它有一个“持久”组件。 “persist”组件使用 JPA（实现：EclipseLink）来持久化对象。

使用 entityManager 的 bean 被声明为 @Stateless，并且通过 @PersistenceContext 注解注入了实体管理器。

问题是，我每次尝试访问 entityManager 时都有一个NullPointerException（意思是，他没有被正确注入）。

@Stateless
@TransactionManagement(TransactionManagementType.CONTAINER)
public class MyBean implements MyBeanLocal {    

    @PersistenceContext(unitName = "MyPersistenceUnit", type = PersistenceContextType.EXTENDED)
    EntityManager entityManager;

    public void insert(MyObject object) {
        try {
            entityManager.persist(object); //NullPointerException here
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

persistence.xml

<?xml version="1.0"  encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.0"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
              http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">

    <persistence-unit name="MyPersistenceUnit"
        transaction-type="JTA">
        <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
        <jta-data-source>MyDataSource</jta-data-source>
        <class>com.myclasses.MyObject</class>>
    </persistence-unit>

</persistence>

我使用工厂获取MyBean的实例：

public class MyBeanFactory
{
    public static MyBean create()
    {
        return new MyBean();
    }
}

我在常规代码中这样使用它：

MyBeanLocal bean = MyBeanFactory.create();

MyBeanLocal 是 MyBean 的接口，它是这样的

@Local(MyBeanLocal.class)
public interface MyBeanLocal {
    public void insert(MyObject object);
}

我尝试通过 @EJB 注释注入 MyBean 实例，但它失败了（每当我尝试使用据称注入的 MyBean 实例时出现 NullPointerException）

当我的应用程序部署在 Weblogic 服务器上时，我既看不到 MyBean，也看不到 MyPersistenceUnit（我看到来自其他组件的 MDB），但我可以看到 下的 MyPersistenceUnit部署 > “我的域” > 配置/设置 > 持久性。 MyDataSource 正常且已连接。

有weblogic服务器的启动日志。

####<15 juil. 2015 09 h 52 CEST> <Notice> <Security> <MyUsername> <AdminServer> <[ACTIVE] ExecuteThread: '0' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1436946746252> <BEA-090082> <Security initializing using security realm myrealm.> 
####<15 juil. 2015 09 h 52 CEST> <Notice> <WebLogicServer> <MyUsername> <AdminServer> <[STANDBY] ExecuteThread: '3' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1436946771648> <BEA-000365> <Server state changed to STANDBY.> 
####<15 juil. 2015 09 h 52 CEST> <Notice> <WebLogicServer> <MyUsername> <AdminServer> <[STANDBY] ExecuteThread: '3' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1436946771650> <BEA-000365> <Server state changed to STARTING.> 
####<15 juil. 2015 09 h 53 CEST> <Warning> <EJB> <MyUsername> <AdminServer> <[ACTIVE] ExecuteThread: '3' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1436946795598> <BEA-012035> <The Remote interface method: public abstract boolean com.myclasses.UtilityRemote.send(com.mytypes.ReqType,java.lang.String) in EJB UtilityBean contains a parameter of type com.mytypes.ReqType which is not serializable. Though the EJB IMMJMSUtilityBean has call-by-reference set to false, this parameter is not serializable and hence will be passed by reference. A parameter can be passed using call-by-value only if the parameter type is serializable.> 
####<15 juil. 2015 09 h 53 CEST> <Notice> <Log Management> <MyUsername> <AdminServer> <[ACTIVE] ExecuteThread: '3' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1436946808540> <BEA-170027> <The server has successfully established a connection with the Domain level Diagnostic Service.> 
####<15 juil. 2015 09 h 53 CEST> <Notice> <WebLogicServer> <MyUsername> <AdminServer> <[STANDBY] ExecuteThread: '1' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1436946809347> <BEA-000365> <Server state changed to ADMIN.> 
####<15 juil. 2015 09 h 53 CEST> <Notice> <WebLogicServer> <MyUsername> <AdminServer> <[STANDBY] ExecuteThread: '1' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1436946809503> <BEA-000365> <Server state changed to RESUMING.> 
####<15 juil. 2015 09 h 53 CEST> <Notice> <Server> <MyUsername> <AdminServer> <[ACTIVE] ExecuteThread: '3' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1436946809774> <BEA-002613> <Channel "Default[1]" is now listening on 127.0.0.1:7001 for protocols iiop, t3, ldap, snmp, http.> 
####<15 juil. 2015 09 h 53 CEST> <Warning> <Server> <MyUsername> <AdminServer> <DynamicListenThread[Default]> <<WLS Kernel>> <> <> <1436946809774> <BEA-002611> <The hostname "MyUsername.MyProxy.com", maps to multiple IP addresses: 172.23.247.5, 0:0:0:0:0:0:0:1.> 
####<15 juil. 2015 09 h 53 CEST> <Notice> <Server> <MyUsername> <AdminServer> <[ACTIVE] ExecuteThread: '3' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1436946809775> <BEA-002613> <Channel "Default[2]" is now listening on 0:0:0:0:0:0:0:1:7001 for protocols iiop, t3, ldap, snmp, http.> 
####<15 juil. 2015 09 h 53 CEST> <Notice> <Server> <MyUsername> <AdminServer> <[ACTIVE] ExecuteThread: '3' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1436946809775> <BEA-002613> <Channel "Default" is now listening on 172.23.247.5:7001 for protocols iiop, t3, ldap, snmp, http.> 
####<15 juil. 2015 09 h 53 CEST> <Notice> <WebLogicServer> <MyUsername> <AdminServer> <[ACTIVE] ExecuteThread: '3' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1436946809776> <BEA-000331> <Started the WebLogic Server Administration Server "AdminServer" for domain "test" running in development mode.> 
####<15 juil. 2015 09 h 53 CEST> <Notice> <WebLogicServer> <MyUsername> <AdminServer> <[ACTIVE] ExecuteThread: '0' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1436946810276> <BEA-000360> <The server started in RUNNING mode.> 
####<15 juil. 2015 09 h 53 CEST> <Notice> <WebLogicServer> <MyUsername> <AdminServer> <[ACTIVE] ExecuteThread: '0' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1436946810280> <BEA-000365> <Server state changed to RUNNING.> 

我怀疑问题是weblogic服务器没有正确处理这个bean，但我不知道如何修复它。

如果有人可以帮助我，我将不胜感激。 如果需要，请向我询问更多代码/配置/上下文。

Answer 1

这里的问题是您如何获取 EJB 引用 - 如果您自己使用“new”构建实例，您将获得的只是 POJO 而不是 EJB - 这意味着您将没有访问任何 EJB 服务，例如依赖注入和事务管理。

要获得真正的 EJB，您应该look up your bean in the initial context：

 MyBeanRemote bean = (MyBeanRemote) new InitialContext().lookup("MyBean/remote");