在配置Play 2以使用JPA(持久性)运行时遇到问题

Question

尝试持久化数据时显示以下错误:

[PersistenceException: [PersistenceUnit: update] class or package not found]
In C:UsersJohannDesktopSODETplay-2.1.1todolistappmodelsStream.java at line 32.

32                EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("update");

Stream.java (a model)

package models;
import javax.persistence.Entity;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Id;
import javax.persistence.Persistence;
import com.restfb.Facebook;
@Entity
public class Stream {
      @Facebook
      @Id
      public String post_id;
      @Facebook
      public String created_time;
      @Facebook
      public String message;
      @Facebook
      public String permalink;
      @Override
      public String toString() {
        return String.format("%s, %s, %s, %s", created_time, message, permalink, post_id);
      }
      public void save(){
          EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("update");
          EntityManager entityManager = entityManagerFactory.createEntityManager();
          entityManager.getTransaction().begin();
          entityManager.persist(this);      
          entityManager.getTransaction().commit();
          entityManager.close();
      }
}

persistence.xml文件在conf/META-INF目录下:

<persistence 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"
             version="2.0">
    <persistence-unit name="update" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <non-jta-data-source>DefaultDS</non-jta-data-source>
        <class>models.Stream</class>
        <class>models.FacebookUser</class>
        <class>models.Comment</class>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>
        </properties>
    </persistence-unit>
</persistence>

这是 build。scala

import sbt._
import Keys._
import play.Project._
object ApplicationBuild extends Build {
  val appName         = "todolist"
  val appVersion      = "1.0-SNAPSHOT"
  val appDependencies = Seq(
    // Add your project dependencies here,
    "com.restfb" % "restfb" % "1.6.11",
    "mysql" % "mysql-connector-java" % "5.1.25",
    "org.hibernate" % "hibernate-entitymanager" % "4.2.1.Final",
    javaCore,
    javaJdbc,
    javaJpa
  )
  val main = play.Project(appName, appVersion, appDependencies).settings(
    // Add your own project settings here      
  )
}

我看了文档，没有找到任何相关信息…

提前感谢!

Answer 1

注意你的application.conf中的名称与update: example:

不一样

jpa.update = updatePersistenceUnit

我认为你没有这一行应用程序必须匹配在application.conf和hibernate文件

注意:hbm2dll中的值update仅用于在模型更改时更新DB模式。我认为你必须使用defaultPersistentUnit名称，因为在application.conf中它可能像这样:

jpa.default = defaultPersistenUnit

然后

db.default.driver =你的驱动db.defalut.url =你的url

Answer 2

您的persistence.xml文件说明了以下配置:

<non-jta-data-source>DefaultDS</non-jta-data-source>

---

<persistence-unit name="update" transaction-type="RESOURCE_LOCAL">

您的application.conf必须包含以下条目

# You can expose this datasource via JNDI if needed (Useful for JPA)
db.default.jndiName=DefaultDS

---

# JPA configuration
# ~~~~~
# You can declare as many Ebean servers as you want.
# By convention, the default server is named `default`
jpa.default=update

查看您的映射或在这里找到一个清晰的解释