Question

我是JPA的新手。我的代码试图连接到Oracle 10.3数据库以填充一些表。但是，在它到达代码填充之前，它会在EntityManagerFactoryImpl.createEntityManager（String）中抛出NullPointerException。我已经验证emf变量不为空。这是Populator.java中的相关代码，就像许多教程示例一样：

public static void main(String[] args) {
    EntityManagerFactory emf =
        Persistence.createEntityManagerFactory("LeaveSchedulerJPA");
    EntityManager em = emf.createEntityManager();

异常跟踪是：

[EL Severe]: 2012-10-11 14:37:02.415--ServerSession(37999235)--java.lang.NullPointerException
    at java.util.ResourceBundle.getBundle(ResourceBundle.java:950)
    at org.eclipse.persistence.exceptions.i18n.ExceptionMessageGenerator.buildMessage(ExceptionMessageGenerator.java:47)
    at org.eclipse.persistence.exceptions.ValidationException.errorDecryptingPassword(ValidationException.java:864)
    at org.eclipse.persistence.internal.security.JCEEncryptor.decryptPassword(JCEEncryptor.java:124)
    at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.updateLogins(EntityManagerSetupImpl.java:1183)
    at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.updateServerSession(EntityManagerSetupImpl.java:1450)
    at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.deploy(EntityManagerSetupImpl.java:372)
    at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.getServerSession(EntityManagerFactoryImpl.java:164)
    at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.createEntityManagerImpl(EntityManagerFactoryImpl.java:221)
    at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:209)
    at com.engilitycorp.leaveschedulerjpa.Populator.main(Populator.java:28)

我的persistence.xml如下。当我从Eclipse使用它来生成与表对应的类时，指定的URL有效。有什么想法吗？

<?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="LeaveSchedulerJPA" transaction-type="RESOURCE_LOCAL">
        <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
        <class>com.engilitycorp.leaveschedulerjpa.Holiday</class>
        <class>com.engilitycorp.leaveschedulerjpa.Leave</class>
        <class>com.engilitycorp.leaveschedulerjpa.LeaveType</class>
        <class>com.engilitycorp.leaveschedulerjpa.Notification</class>
        <class>com.engilitycorp.leaveschedulerjpa.NotificationType</class>
        <class>com.engilitycorp.leaveschedulerjpa.Role</class>
        <class>com.engilitycorp.leaveschedulerjpa.User</class>
        <properties>
        <property name="javax.persistence.jdbc.url" value="jdbc:oracle:thin:@localhost:1521:xe"/>
            <property name="javax.persistence.jdbc.user" value="leavescheduler"/>
            <property name="javax.persistence.jdbc.password" value="xxxx"/>
            <property name="javax.persistence.jdbc.driver" value="oracle.jdbc.OracleDriver"/>
        </properties>
    </persistence-unit>
</persistence>

Answer 1

问题是我试图测试持久性，就像它是一个独立的Java应用程序一样。该文档指出EntityManagerFactoryImpl维护“对活动ServerSession的引用”。当我在WebLogic中运行相同的代码时，它工作正常。

同事能够运行与独立Java应用程序相同的代码。我还没弄清楚关键的配置差异是什么。

为什么EntityManagerFactoryImpl.createEntityManager（）会导致NullPointerException？

1 个答案: