0
我最近切换了开发机器，现在正在将对象写入/从持久性数据库中检索对象不再有效。当我尝试在我的新机器上调试webapp项目时发生这种情况。 它适用于我的旧笔记本电脑，但不知何故将不会在新的笔记本电脑上。我也将webapp部署到服务器，并且一切都按预期工作。Eclipselink：将对象写入/从持久性数据库中检索对象时出错
我得到以下两个错误信息与数据库进行交互：
写作对象数据库：
SEVERE: Exception sending context initialized event to listener instance of class org.example.webapp.startup.ServletContextClass
java.lang.IllegalArgumentException: Object: [email protected] is not a known entity type.
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.registerNewObjectForPersist(UnitOfWorkImpl.java:4222)
at org.eclipse.persistence.internal.jpa.EntityManagerImpl.persist(EntityManagerImpl.java:496)
at org.example.webapp.changelog.dao.ChangeLogDao.addChangeLog(ChangeLogDao.java:42)
at org.example.webapp.startup.ServletContextClass.initializeChangeLog(ServletContextClass.java:104)
at org.example.webapp.startup.ServletContextClass.contextInitialized(ServletContextClass.java:59)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4797)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5221)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1408)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1398)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
代码写入到数据库：
public void addChangeLog(ChangeLog changeLog, EntityManagerFactory emf) {
String changeLogId = changeLog.getModelResource();
if(!contentProvider.containsKey(changeLogId)) {
//create new user
EntityManager em = emf.createEntityManager();
em.getTransaction().begin();
em.persist(changeLog);
em.getTransaction().commit();
em.close();
contentProvider.put(changeLogId, changeLog);
}
检索对象从数据库：
SEVERE: Exception sending context initialized event to listener instance of class org.example.webapp.startup.ServletContextClass
java.lang.IllegalArgumentException: An exception occurred while creating a query in EntityManager:
Exception Description: Problem compiling [SELECT c FROM ChangeLog c].
[14, 23] The abstract schema type 'ChangeLog' is unknown.
at org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1585)
at org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1605)
at org.example.webapp.startup.ServletContextClass.contextInitialized(ServletContextClass.java:59)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4797)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5221)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1408)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1398)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
代码从数据库中读取：
List<ChangeLog> changeLogList = em.createQuery("SELECT c FROM ChangeLog c",
ChangeLog.class).getResultList();
这里是如何ChangeLog类的样子：
package org.example.utility.trs.objects;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.NamedQuery;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlRootElement;
@Entity
@NamedQuery(name="ChangeLog.findAll", query="SELECT c FROM ChangeLog c")
@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class ChangeLog implements Serializable {
private static final long serialVersionUID = 123L;
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long changeLogId;
...
}
这是persistence.xml文件：
<?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="webapp-name" transaction-type="RESOURCE_LOCAL">
<class>org.example.utility.trs.objects.ChangeLog</class>
<exclude-unlisted-classes>false</exclude-unlisted-classes>
<properties>
<!-- mysql persistence driver -->
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/persistence"/>
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
<property name="javax.persistence.jdbc.username" value="admin"/>
<property name="javax.persistence.jdbc.password" value="password"/>
<!-- EclipseLink should create the database schema automatically -->
<property name="eclipselink.ddl-generation.output-mode" value="database" />
<property name="javax.persistence.jdbc.user" value="admin"/>
</properties>
</persistence-unit>
</persistence>
下面是部分包含持久性库的pom.xml文件。我可以张贴整个文件，如果这个任何assistence：
<!-- persistence api -->
<dependency>
<groupId>org.hibernate.javax.persistence</groupId>
<artifactId>hibernate-jpa-2.0-api</artifactId>
<version>1.0.1.Final</version>
</dependency>
<dependency>
<groupId>org.eclipse.persistence</groupId>
<artifactId>eclipselink</artifactId>
<version>2.5.0</version>
</dependency>
我可以连接到数据库，并有一个与内容的表，我是能够创造和我的老开发机器上阅读。 因此，我认为这个问题相当于eclipselink的配置，而不是代码中的实际问题。也许这是在eclipse项目中配置JPA构面的问题。
但是我不知道如何调试这个问题。
另一方面，ChangeLog类来自一个不同的项目，该项目存储在我的本地Maven存储库中，并且未在webapp项目中定义。所以这可能是一个问题。尽管这在我的旧机器上从来都不是问题。
任何帮助表示赞赏