Glassfish 3.1.1的persistence.xml

Question

我对glassfish,JPA等都很陌生,我在设置它时遇到了很多问题.我打算做的是一个带有持久后端的简单RESTful服务.我使用glassfish3作为应用程序服务器,并已使用jersey-library部署了一个简单的REST服务.现在我想通过JPA提供对数据库的访问.Glassfish附带JavaDB/derby和EclipseLink,是吗？所以,我想用那个:-)

我在META-INF中创建了一个persistence.xml:

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0"
    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_1_0.xsd">
  <persistence-unit name="myPU" transaction-type="JTA">
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
    <exclude-unlisted-classes>false</exclude-unlisted-classes>
    <properties>
      <property name="javax.persistence.jdbc.driver"   value="org.apache.derby.jdbc.ClientDataSource" /> <!-- org.apache.derby.jdbc.EmbeddedDriver -->
      <property name="javax.persistence.jdbc.url"      value="jdbc:derby://localhost:1527/sample;create=true" />
      <property name="javax.persistence.jdbc.user"     value="APP" />
      <property name="javax.persistence.jdbc.password" value="APP" />
      <property name="eclipselink.ddl-generation"      value="create-tables" />
    </properties>
  </persistence-unit>
</persistence>

然后我在我的资源中创建了一个字段,我想访问/存储som数据:

@PersistenceUnit(unitName = "myPU")
EntityManagerFactory emf;

但"emf"总是NULL :-(

我想我的persistence.xml配置不合适.

如果有人有提示,我做错了,真的很高兴......

谢谢!

Answer 1

我认为最好为数据库连接创建JNDI.您可以使用GlassFish轻松完成.

首先创建连接池(您将设置数据库连接设置);

资源 - > JDBC-> JDBC连接池

之后,此池的JNDI名称为crate;

资源 - > JDBC-> JDBC资源

所以假设您将JNDI名称设置为"dbCon"

在这里你的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="myPU" transaction-type="JTA">
    <jta-data-source>dbCon</jta-data-source>
    <exclude-unlisted-classes>false</exclude-unlisted-classes>
    <properties/>
  </persistence-unit>
</persistence>

注意:您必须将jdbc jar复制到\ glassfish-3.1.1\glassfish\domains\domain1\lib\ext

Answer 2

我现在有解决问题的方法.这是相应的配置:

• 玻璃鱼3.1.1
• 内置JavaDB/derby数据库:jdbc/__ default
• glassfish的JPA,这是eclipselink
• (JAX RS:泽西岛,随玻璃鱼一起发货)

因此,您必须在src文件夹中创建文件夹"META-INF"并将persistence.xml放在那里:

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0"
    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_1_0.xsd">
  <persistence-unit name="myPU" transaction-type="JTA">
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
    <jta-data-source>jdbc/__default</jta-data-source>
    <exclude-unlisted-classes>false</exclude-unlisted-classes>
    <properties>
        <property name="eclipselink.ddl-generation" value="drop-and-create-tables" />
    </properties>
  </persistence-unit>
</persistence>

我之前在WebContent的META-INF中创建了.xml,这是错误的.您也不必引用任何其他库,因为您添加了glassfish模块.

现在我创建了一个JavaBean,我在其中注入了PersistenceUnit:

@Stateless
public class StorageService {

    @PersistenceContext(unitName = "myPU")
    EntityManager em;

...
}

这个注入我的Jersey-Servlets资源类:

@Path("/someres")
@Produces(MediaType.APPLICATION_XML)
@Stateless
public class SomeRes {

    @EJB
    StorageService storageService;

...
}

注入只有在类标记为"@Stateless"时才有效.