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[英]How do I setup a project in Eclipse for JSP, Servlet, JPA, Hibernate web development
[英]how to setup JPA project to work with Hibernate?
我在使用純JPA機制但將Hibernate作為實現層的Eclipse中設置項目時遇到了麻煩。
我有一個簡單的程序,其中包含2個類,這些類通過使用注釋定義的多對多關系鏈接。
我想避免使用休眠特定的配置,以保持與數據庫的盡可能獨立。 例如,我希望所有配置都在persistence.xml文件中。
每次我啟動程序時,都會出現以下錯誤:
juil. 18, 2014 7:28:11 PM org.hibernate.ejb.HibernatePersistence logDeprecation
WARN: HHH015016: Encountered a deprecated javax.persistence.spi.PersistenceProvider [org.hibernate.ejb.HibernatePersistence]; use [org.hibernate.jpa.HibernatePersistenceProvider] instead.
juil. 18, 2014 7:28:11 PM org.hibernate.ejb.HibernatePersistence logDeprecation
WARN: HHH015016: Encountered a deprecated javax.persistence.spi.PersistenceProvider [org.hibernate.ejb.HibernatePersistence]; use [org.hibernate.jpa.HibernatePersistenceProvider] instead.
juil. 18, 2014 7:28:11 PM org.hibernate.ejb.HibernatePersistence logDeprecation
WARN: HHH015016: Encountered a deprecated javax.persistence.spi.PersistenceProvider [org.hibernate.ejb.HibernatePersistence]; use [org.hibernate.jpa.HibernatePersistenceProvider] instead.
juil. 18, 2014 7:28:11 PM org.hibernate.jpa.internal.util.LogHelper logPersistenceUnitInformation
INFO: HHH000204: Processing PersistenceUnitInfo [
name: Test-Cache-Hibernate
...]
juil. 18, 2014 7:28:11 PM org.hibernate.Version logVersion
INFO: HHH000412: Hibernate Core {4.3.5.Final}
juil. 18, 2014 7:28:11 PM org.hibernate.cfg.Environment <clinit>
INFO: HHH000206: hibernate.properties not found
juil. 18, 2014 7:28:11 PM org.hibernate.cfg.Environment buildBytecodeProvider
INFO: HHH000021: Bytecode provider name : javassist
juil. 18, 2014 7:28:11 PM org.hibernate.annotations.common.reflection.java.JavaReflectionManager <clinit>
INFO: HCANN000001: Hibernate Commons Annotations {4.0.4.Final}
Initial SessionFactory creation failed.javax.persistence.PersistenceException: Unable to build entity manager factory
上下文:Eclipse Luna JPA 2.1 Hibernate 4.3.5
這是我的persistence.xml:
<?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="Test-Cache-Hibernate" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
<non-jta-data-source>datasource</non-jta-data-source>
<shared-cache-mode>ENABLE_SELECTIVE</shared-cache-mode>
<properties>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/testcache"/>
<property name="javax.persistence.jdbc.user" value="root"/>
<property name="javax.persistence.jdbc.password" value="admin"/>
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
</properties>
</persistence-unit>
</persistence>
我在Singleton類中隔離了實體管理器的創建,如下所示:
package src.persistence.dbmanager;
import javax.persistence.EntityManager;
import javax.persistence.Persistence;
public class DBManager {
public static final EntityManager entityManager;
static {
try {
entityManager = Persistence.createEntityManagerFactory("Test-Cache-Hibernate").createEntityManager();
} catch (Throwable ex) {
throw new ExceptionInInitializerError(ex);
}
}
public static EntityManager getEntityManager() {
return entityManager;
}
}
我在使用DAO對象手動注入EntityManager時遇到上述錯誤:
private EntityManager entityManager = DBManager.getEntityManager();
編輯1:這是我的DAO對象之一的代碼:
package acs.testcache.persistence.dao;
import java.util.HashSet;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;
import acs.testcache.persistence.entities.MyChildObject;
import acs.testcache.persistence.entities.MyParentObject;
public class MyChildDAO extends MyCommonDAO<MyChildObject> {
@PersistenceContext(unitName="Test-Cache-Hibernate")
private EntityManager entityManager;
public MyChildDAO() {
super(MyChildObject.class);
}
public EntityManager getEntityManager() {
return entityManager;
}
@SuppressWarnings("unchecked")
public void getParents(MyChildObject c){
StringBuilder hqlQuery = new StringBuilder();
hqlQuery.append("select c.parentsObjects from MyChildObject c where c.id = :id");
Query q = getEntityManager().createQuery(hqlQuery.toString()).setParameter("id", c.getId()).setHint("org.hibernate.cacheable", true);
List<MyParentObject> result = q.getResultList();
c.setParents(new HashSet<MyParentObject>(result));
}
}
持久性管理器永遠不會被注入。
當我嘗試使用注釋自動注入注釋時,查詢時出現空指針異常。
有人可以幫忙嗎?
謝謝。
請提供有關如何使用注釋注入EntityManager
的代碼。 您是否嘗試過像這樣使用@PersistenceContext
注釋?
@PersistenceContext私有EntityManager實體管理器;
在這種情況下,使用@Component
, @Component
@Resource
(或任何Java的本機等效注解)將不起作用。
在persistence.xml
我看不到任何實體聲明。 您應該在此處定義實體類。 類似於<class>com.example.package.TestEntity<class>
。
同樣在DBManager
您應該指定什么是資源和EntityManger。 使用DI,例如: @PersistenceContext(unitName = "Test-Cache-Hibernate")
private EntityManager em;
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