Java SE环境中的JPA:在persistence.xml中装入没有防御的实体类 [英] JPA in Java SE environment: Entity classes loaded without defenition in persistence.xml

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问题描述

我正在为Oracle JPAD认证做准备，所以我在Java SE环境中与实体打交道(至少，这就是我的想法...).我注意到我希望有人能对此有所启发.

I'm prepping for Oracle JPAD certification, so I'm playing around a littlebit with Entities in a Java SE environment (at least, that's what I think...). I noticed something on which I'm hoping someone can shed a light on it.

我正在阅读Pro JPA2.在第2章末尾的某个地方，有一个示例persistence.xml文件，其中定义了一个类.好的，这就是在Java SE环境中使用的方法，因为您实际上并没有将整个容器放在容器中.但这是一件奇怪的事情:我有两个用@Entity注释的Entity类，并且还没有将其中任何一个添加到persistence.xml中.但是仍然在加载！我吓坏了.我现在唯一能想到的就是我不在SE环境中，或者它是一个新的休眠功能...

The book Pro JPA2 is what I'm reading. Somewhere at the end of chapter 2, there's an example persistence.xml file with a class defined in it. Ok, so that's the way to go in a Java SE environment, because you don't really have the whole shebang inside a container. But here's the strange thing: I have two Entity classes annotated with @Entity and haven't added any of these to the persistence.xml. But still the're being loaded! I'm gobsmacked. The only thing I can think of now, is that I'm not in an SE environment or it's a new hibernate feature...

Persistence.xml:

<?xml version="1.0" encoding="UTF-8" ?>
<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"
  version="2.0" xmlns="http://java.sun.com/xml/ns/persistence">
  <persistence-unit name="employees" transaction-type="RESOURCE_LOCAL">

    <properties>
      <property name="javax.persistence.jdbc.driver" value="org.hsqldb.jdbcDriver" />
      <property name="javax.persistence.jdbc.url" value="jdbc:hsqldb:mem:." />
      <property name="javax.persistence.jdbc.user" value="SA" />
      <property name="javax.persistence.jdbc.password" value="" />

      <property name="hibernate.show_sql" value="false" />
      <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect" />
      <property name="hibernate.connection.shutdown" value="true" />
      <property name="hibernate.hbm2ddl.auto" value="create-drop" />
    </properties>

  </persistence-unit>
</persistence>

实体:

@Entity
   @Access(AccessType.FIELD)
   public class Employee {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private Date startDate;
    private Long salary;

    public Employee() {
    }

    public Employee(String name) {
        this.name = name;
    }

    public Employee(String name, Long salary) {
        this.name = name;
        this.salary = salary;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Date getStartDate() {
        return startDate;
    }

    public void setStartDate(Date startDate) {
        this.startDate = startDate;
    }

    public Long getSalary() {
        return salary;
    }

    public void setSalary(Long salary) {
        this.salary = salary;
    }

    @Override
    public String toString() {
        return "Employee [name=" + name + ", salary=" + salary + ", startDate=" + startDate + "]";
    }
}

一个测试:

public class TestConnection {

    private static EntityManagerFactory entityManagerFactory;
    private static EntityManager entityManager;
    private static final String PERSISTENCE_UNIT_NAME = "employees";

    @BeforeClass
    public static void initEntityManager() throws Exception {
        entityManagerFactory = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME);
        entityManager = entityManagerFactory.createEntityManager();
        TableStructurePrinter.outputTableStructure(entityManager);
    }

    @AfterClass
    public static void closeEntityManager() {
        entityManager.close();
        entityManagerFactory.close();
    }

    @BeforeMethod
    public void setupDB() throws Exception {
        entityManager.getTransaction().begin();
        LoadEmployees.load(entityManager, 4);
    }

    @AfterMethod
    public void cleanDB() throws Exception {
        entityManager.getTransaction().rollback();
    }

    @Test
    public void testCountEmployees() {
        Query q = entityManager.createQuery("select e from Employee e");
        assertEquals(q.getResultList().size(), 4);
    }

}

还有我的TableStructurePrinter的输出(这是来自INFORMATION_SCHEMA.SYSTEM_TABLES和INFORMATION_SCHEMA.SYSTEM_COLUMNS的简单选择语句):

And the output from my TableStructurePrinter (this is a simple select statement from INFORMATION_SCHEMA.SYSTEM_TABLES and INFORMATION_SCHEMA.SYSTEM_COLUMNS):

T.TABLE_TYPE         T.TABLE_NAME           C.ORDINAL_POSITION C.COLUMN_NAME                 C.TYPE_NAME        C.COLUMN_SIZE
===================  ===================   =================== ===================   ===================  ===================
TABLE                EMPLOYEE                                1 ID                                 BIGINT                   64
TABLE                EMPLOYEE                                2 NAME                              VARCHAR                  255
TABLE                EMPLOYEE                                3 SALARY                             BIGINT                   64
TABLE                EMPLOYEE                                4 STARTDATE                       TIMESTAMP                   26

Java SE环境中的JPA:在persistence.xml中装入没有防御的实体类 [英] JPA in Java SE environment: Entity classes loaded without defenition in persistence.xml

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Java SE环境中的JPA:在persistence.xml中装入没有防御的实体类 [英] JPA in Java SE environment: Entity classes loaded without defenition in persistence.xml

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