Question

我已经阻止这个问题好几个小时了，我不明白这个问题，因为它与我项目的另一个实体一起正常工作。我在Eclipse IDE中使用Glassfish 4，JPA 2和EJB 3创建了一个Java EE项目。我正在使用mysql数据库进行存储。

我创建了一个名为Company的实体bean和一个DAO来管理它。我做了所有它需要工作，它运作良好。问题是我为另一个名为Newsletter的实体bean做了完全相同的事情，但是这个不起作用。 Java抛出EJBException，告诉我抽象模式是未知的，但它存在于DB中。表公司和时事通讯都在同一个数据库中，因此我对它们使用了相同的持久性单元。

我在谷歌或这里找到的一些问题是通过将这个类添加到persitence-unit来解决的，我做了它，但它仍然引发了我的异常。

这是我的NEWSLETTER表：

    +--------------+--------------+------+-----+---------+----------------+
    | Field        | Type         | Null | Key | Default | Extra          |
    +--------------+--------------+------+-----+---------+----------------+
    | idNewsletter | int(11)      | NO   | PRI | NULL    | auto_increment |
    | firstname    | varchar(100) | NO   |     | NULL    |                |
    | lastname     | varchar(100) | NO   |     | NULL    |                |
    | email        | varchar(255) | NO   |     | NULL    |                |
    +--------------+--------------+------+-----+---------+----------------+

我的豆子通讯：

    @Entity
    public class Newsletter {

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private Long idNewsletter;

        @Column(name="firstname")
        private String firstname;

        @Column(name="lastname")
        private String lastname;

        @Column(name="email")
        private String email;

    }

这是我的persistence.xml：

    <?xml version="1.0" encoding="UTF-8"?>
    <persistence    version="2.0"
    xmlns="http://java.sun.com/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
    http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">

<persistence-unit name="2lifedb_PU" transaction-type="JTA">
    <jta-data-source>jdbc/bonecp_resource</jta-data-source>
    <class>com.twolife.beans.User</class>
    <class>com.twolife.beans.Company</class>
    <class>com.twolife.beans.Office</class>
    <class>com.twolife.beans.BankDetails</class>
    <class>com.twolife.beans.Logo</class>
    <class>com.twolife.beans.Newsletter</class>
    <properties>
        <property name="eclipselink.logging.level.sql" value="FINE"/>
        <property name="eclipselink.logging.parameters" value="true"/>
    </properties>
</persistence-unit>

DAO课程：

    @Stateless
    public class DAONewsletter {

        private static final String SQL_SELECT_NEWSLETTER = "SELECT n FROM NEWSLETTER n WHERE n.email = :email";

        @PersistenceContext(unitName="2lifedb_PU")
        private EntityManager em;

        public void create(Newsletter newsletter) throws DAOException {
            try {
                em.persist(newsletter);
            } catch (Exception e) {
                throw new DAOException(e);
            }
        }

        public Newsletter find(String email) throws DAOException {
            Newsletter newsletter = new Newsletter();

            Query query = em.createQuery(SQL_SELECT_NEWSLETTER);
            query.setParameter("email", email);

            try {
                newsletter = (Newsletter) query.getSingleResult();
            } catch (NoResultException e) {
                return null;
            } catch (Exception e) {
                throw new DAOException(e);
            }

            return newsletter;
       }
    }

最后，这是我异常的堆栈跟踪：

    Caused by: java.lang.IllegalArgumentException: An exception occurred while creating a query in EntityManager: 
    Exception Description: Problem compiling [SELECT n FROM NEWSLETTER n WHERE n.email = :email]. 
    [14, 24] The abstract schema type 'NEWSLETTER' is unknown.
    [33, 40] The state field path 'n.email' cannot be resolved to a valid type.
        at org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1585)
        at com.sun.enterprise.container.common.impl.EntityManagerWrapper.createQuery(EntityManagerWrapper.java:456)
        at com.twolife.dao.DAONewsletter.find(DAONewsletter.java:30)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        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:4695)
        at com.sun.ejb.EjbInvocation.invokeBeanMethod(EjbInvocation.java:630)
        at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:822)
        at com.sun.ejb.EjbInvocation.proceed(EjbInvocation.java:582)
        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:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        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:4667)
        at com.sun.ejb.containers.BaseContainer.intercept(BaseContainer.java:4655)
        at com.sun.ejb.containers.EJBLocalObjectInvocationHandler.invoke(EJBLocalObjectInvocationHandler.java:212)
        ... 36 more
    Caused by: Exception [EclipseLink-0] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.JPQLException
    Exception Description: Problem compiling [SELECT n FROM NEWSLETTER n WHERE n.email = :email]. 
    [14, 24] The abstract schema type 'NEWSLETTER' is unknown.
    [33, 40] The state field path 'n.email' cannot be resolved to a valid type.
        at org.eclipse.persistence.internal.jpa.jpql.HermesParser.buildException(HermesParser.java:155)
        at org.eclipse.persistence.internal.jpa.jpql.HermesParser.validate(HermesParser.java:347)
        at org.eclipse.persistence.internal.jpa.jpql.HermesParser.populateQueryImp(HermesParser.java:278)
        at org.eclipse.persistence.internal.jpa.jpql.HermesParser.buildQuery(HermesParser.java:163)
        at org.eclipse.persistence.internal.jpa.EJBQueryImpl.buildEJBQLDatabaseQuery(EJBQueryImpl.java:142)
        at org.eclipse.persistence.internal.jpa.EJBQueryImpl.buildEJBQLDatabaseQuery(EJBQueryImpl.java:116)
        at org.eclipse.persistence.internal.jpa.EJBQueryImpl.<init>(EJBQueryImpl.java:102)
        at org.eclipse.persistence.internal.jpa.EJBQueryImpl.<init>(EJBQueryImpl.java:86)
        at org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1583)
        ... 60 more

如果anoyone得到一个想法，那将是非常有帮助的！抱歉一些英语错误，这不是我的母语......

Answer 1

em.createQuery（）需要JPQL查询，而不是SQL查询。 SQL和JPQL不是同一种语言。 SQL适用于表和列。 JPQL与实体，字段/属性和关联一起使用。绝不使用表名和列名。语法类似，但不同。

您的实体名为Newsletter，但您的查询使用NEWSLETTER。类名称区分大小写。

Answer 2

我在带有eclipselink 2.6的wildfly 10.0中遇到了同样的问题。

我解决了将以下系统属性添加到standalone.xml文件

<?xml version='1.0' encoding='UTF-8'?>

<server xmlns="urn:jboss:domain:4.2">
<system-properties>
    <property name="eclipselink.archive.factory" value="org.jipijapa.eclipselink.JBossArchiveFactoryImpl"/>
</system-properties>
...
</server>

EJB未知的抽象模式但它存在于DB中

2 个答案: