尝试对关闭的 EntityManager 执行操作（在命名查询上调用 setParameter() 函数时）

Question

我有 Netbeans_8.0.2 来使用 Glassfish_4.1 开发我的项目。在无状态 bean 中，我在具有 @postconstruct 注释的方法中初始化命名查询。但是当我尝试在命名查询上调用 setParameter() 时，它会引发 IllegalStateException。

实体类：

@Entity
@Table(name = "ORDERS")
@XmlRootElement
@NamedQueries({
@NamedQuery(name = "OrdersEntity.findByClientNum", query = "SELECT o FROM OrdersEntity o WHERE o.orderClientNum = :orderClientNum")})

public class OrdersEntity implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "ORDER_SYS_NUM")
    private Integer orderSysNum;
    @Column(name = "ORDER_CLIENT_NUM")
    private String OrderClientNum;

    public OrdersEntity() {
    }

    public OrdersEntity(Integer sysNum) {
        this.dtOrderSysNum = sysNum;
    }

//setters & getters

}

无状态 Bean：

@Stateless
public class OrderServices implements OrderServicesRemote {
    @PersistenceContext(unitName = "OrderServicesPU")
    private EntityManager em;

    private TypedQuery<OrdersEntity>  queryFindOrderByOrderClientNum;

    @PostConstruct
    private void initializeBean() {
        queryFindOrderByOrderClientNum = em.createNamedQuery("OrdersEntity.findByClientNum", OrdersEntity.class);
        //comment 1: the following line of code works
        //OrdersEntity oe = queryFindOrderByOrderClientNum.setParameter("OrderClientNum", "OR123").getSingleResult();        
    }


    private OrdersEntity retrieveOrderEntity(String orderClientNum) {
        //comment 2: the following line of code causes the issue
            queryFindOrderByOrderClientNum.setParameter("OrderClientNum",   orderClientNum);

        OrdersEntity oe;
        try {
            oe = queryFindOrderByOrderClientNum.getSingleResult();
        } catch (NoResultException nre) {
            throw new OrderNotFoundException();
        } catch (NonUniqueResultException nure) {
           throw new OrderNotFoundException();
        }

        return oe;
    }
}

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="RewardsManagerServicesPU" transaction-type="JTA">
    <jta-data-source>jdbc/Rewards_Pool</jta-data-source>
    <exclude-unlisted-classes>false</exclude-unlisted-classes>
    <properties>
      <property name="eclipselink.jdbc.batch-writing" value="JDBC"/>
    </properties>
  </persistence-unit>
</persistence>

详情：

1. 我在调试器中运行了程序，发现注释 2 下面的代码行导致了问题
2. 实体管理器正常工作。我在这个无状态 bean 中还有其他几个函数，它们都可以很好地使用它。
3. 如注释 1 所示，如果我在命名查询初始化后立即对其调用 setParameter() 函数，它会起作用。

堆栈跟踪：

Warning: A system exception occurred during an invocation on EJB OrderServices, method: public OrderServices.retrieveOrderVO(java.lang.String) throws OrderNotFoundException
Warning: javax.ejb.EJBException
at com.sun.ejb.containers.EJBContainerTransactionManager.processSystemException(EJBContainerTransactionManager.java:748)
at com.sun.ejb.containers.EJBContainerTransactionManager.completeNewTx(EJBContainerTransactionManager.java:698)
at com.sun.ejb.containers.EJBContainerTransactionManager.postInvokeTx(EJBContainerTransactionManager.java:503)
at com.sun.ejb.containers.BaseContainer.postInvokeTx(BaseContainer.java:4566)
at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:2074)
at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:2044)
at com.sun.ejb.containers.EJBObjectInvocationHandler.invoke(EJBObjectInvocationHandler.java:212)
at com.sun.ejb.containers.EJBObjectInvocationHandlerDelegate.invoke(EJBObjectInvocationHandlerDelegate.java:79)
at com.sun.proxy.$Proxy301.retrieveOrderVO(Unknown Source)
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:483)
at com.sun.corba.ee.impl.presentation.rmi.ReflectiveTie.dispatchToMethod(ReflectiveTie.java:143)
at com.sun.corba.ee.impl.presentation.rmi.ReflectiveTie._invoke(ReflectiveTie.java:173)
at com.sun.corba.ee.impl.protocol.ServerRequestDispatcherImpl.dispatchToServant(ServerRequestDispatcherImpl.java:528)
at com.sun.corba.ee.impl.protocol.ServerRequestDispatcherImpl.dispatch(ServerRequestDispatcherImpl.java:199)
at com.sun.corba.ee.impl.protocol.MessageMediatorImpl.handleRequestRequest(MessageMediatorImpl.java:1549)
at com.sun.corba.ee.impl.protocol.SharedCDRClientRequestDispatcherImpl.marshalingComplete(SharedCDRClientRequestDispatcherImpl.java:119)
at com.sun.corba.ee.impl.protocol.ClientDelegateImpl.invoke(ClientDelegateImpl.java:258)
at com.sun.corba.ee.impl.presentation.rmi.StubInvocationHandlerImpl.privateInvoke(StubInvocationHandlerImpl.java:198)
at com.sun.corba.ee.impl.presentation.rmi.StubInvocationHandlerImpl.invoke(StubInvocationHandlerImpl.java:150)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:415)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:282)
at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:459)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:167)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:201)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:175)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:284)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:201)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:133)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:112)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:561)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:56)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:565)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:545)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.IllegalStateException: Attempting to execute an operation on a closed EntityManager.
at org.eclipse.persistence.internal.jpa.EntityManagerImpl.verifyOpen(EntityManagerImpl.java:1913)
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.setParameter(EJBQueryImpl.java:592)
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.setParameter(EJBQueryImpl.java:1)
at com.sun.enterprise.container.common.impl.QueryWrapper.setParameter(QueryWrapper.java:284)
at com.sun.enterprise.container.common.impl.TypedQueryWrapper.setParameter(TypedQueryWrapper.java:122)
at OrderServices.retrieveOrderEntity(OrderServices.java:394)
at OrderServices.retrieveOrderVO(OrderServices.java:656)
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:483)
at org.glassfish.ejb.security.application.EJBSecurityManager.runMethod(EJBSecurityManager.java:1081)
at org.glassfish.ejb.security.application.EJBSecurityManager.invoke(EJBSecurityManager.java:1153)
at com.sun.ejb.containers.BaseContainer.invokeBeanMethod(BaseContainer.java:4786)
at com.sun.ejb.EjbInvocation.invokeBeanMethod(EjbInvocation.java:656)
at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:822)
at com.sun.ejb.EjbInvocation.proceed(EjbInvocation.java:608)
at org.jboss.weld.ejb.AbstractEJBRequestScopeActivationInterceptor.aroundInvoke(AbstractEJBRequestScopeActivationInterceptor.java:55)
at org.jboss.weld.ejb.SessionBeanInterceptor.aroundInvoke(SessionBeanInterceptor.java:52)
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:483)
at com.sun.ejb.containers.interceptors.AroundInvokeInterceptor.intercept(InterceptorManager.java:883)
at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:822)
at com.sun.ejb.EjbInvocation.proceed(EjbInvocation.java:608)
at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.doCall(SystemInterceptorProxy.java:163)
at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.aroundInvoke(SystemInterceptorProxy.java:140)
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:483)
at com.sun.ejb.containers.interceptors.AroundInvokeInterceptor.intercept(InterceptorManager.java:883)
at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:822)
at com.sun.ejb.containers.interceptors.InterceptorManager.intercept(InterceptorManager.java:369)
at com.sun.ejb.containers.BaseContainer.__intercept(BaseContainer.java:4758)
at com.sun.ejb.containers.BaseContainer.intercept(BaseContainer.java:4746)
at com.sun.ejb.containers.EJBObjectInvocationHandler.invoke(EJBObjectInvocationHandler.java:205)
... 50 more

Answer 1

首先，通常不鼓励在无状态 bean 中使用属性 (queryFindOrderByOrderClientNum)，因为这通常没有意义。有点过于简单化了，但可以将其视为多个客户端之间共享对象的无状态 bean。使用注入 (em) 很好，因为容器会确保每个客户端都有一个合适的实例。

在PostConstruct 中，您正在创建与当前事务和当前实体管理器关联的命名查询的新实例。在PostConstruct 方法完成后，事务被提交并且entitymanager“被丢弃”。这意味着您的命名查询实例将不再工作。

实际上根本没有理由预先分配命名查询。每次查询时只需创建一个新的命名查询。在您的情况下，请在方法 retrieveOrderEntity 中创建查询。

如果您尝试通过“缓存”命名查询创建来进行优化，它永远不会起作用。应用程序服务器、持久性提供程序和数据库将使用许多技术进行优化。依赖它们并记住“过早的优化是万恶之源”