Question

我对Hibernate相当新手。我用Hibernate和JPA编写了一个程序。问题是，当我调用Persistence.createEntityManagerFactory（“name”）时，返回EntityManagerFactory需要至少3000毫秒（甚至8000毫秒）。

我的PersistenceCtrl中的代码如下：

import javax.persistence.*;

public class PersistenceCtrl {

private EntityManager entityManager;
private EntityManagerFactory entityManagerFactory;

public PersistenceCtrl() {
    startPersistenceCtrl();
}

public EntityManager getEntityManager() {
    return entityManager;
}

public void setEntityManager(EntityManager entityManager) {
    this.entityManager = entityManager;
}

public EntityManagerFactory getEntityManagerFactory() {
    return entityManagerFactory;
}

public void setEntityManagerFactory(EntityManagerFactory entityManagerFactory) {
    this.entityManagerFactory = entityManagerFactory;
}

public void startPersistenceCtrl(){
    this.setEntityManagerFactory(Persistence.createEntityManagerFactory("name"));
    this.setEntityManager(this.getEntityManagerFactory().createEntityManager());        
}

public void closePersistenceCtrl(){
    //EntityTransaction et = this.getEntityManager().getTransaction();
    //et.begin();
    //this.getEntityManager().flush();
    //et.commit();
    this.getEntityManager().close();
    this.getEntityManagerFactory().close();
}

public void saveObject(Object obj){
    EntityTransaction et = this.getEntityManager().getTransaction();
    et.begin();

    this.getEntityManager().persist(obj);

    et.commit();
}

public void removeObject(Object obj){
    EntityTransaction et = this.getEntityManager().getTransaction();
    et.begin();

    this.getEntityManager().remove(obj);

    et.commit();
}

}

我的persistence.xml如下：

<?xml version="1.0" encoding="UTF-8"?>
<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="name">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>

    <!-- My classes -->

    <properties>
        <property name="hibernate.validator.apply_to_ddl" value="false"/>
        <property name="hibernate.validator.autoregister_listeners" value="false"/>
        <property name="hibernate.cache.provider_class" value="org.hibernate.cache.NoCacheProvider"/>
        <property name="javax.persistence.validation.mode" value="ddl"/>
        <property name="javax.persistence.jdbc.url" value="url"/>
        <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
        <property name="javax.persistence.jdbc.user" value="user"/>
        <property name="javax.persistence.jdbc.password" value="password"/>
        <property name="javax.persistence.jdbc.initialSize" value="2"/>
        <property name="javax.persistence.jdbc.minIdle" value="0"/>
        <property name="javax.persistence.jdbc.maxActive" value="10"/>
        <!-- <property name="hibernate.hbm2ddl.auto" value="update"/> -->
        <!-- <property name="javax.persistence.jdbc.minEvictableIdleTimeMillis" value="120000"/> -->
        <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5InnoDBDialect"/>
    </properties>
</persistence-unit>

这是正常的吗？

使用Hibernate的SessionFactory会更快吗？

谢谢。

Answer 1

EntityManagerFactory是一个线程安全的对象，应该只在应用程序的生命周期内创建一次。如果创建需要3秒钟，那应该没那么重要。

没有理由关闭EntityManagerFactory并像你似乎一样重新打开它。

Hibernate - createEntityManagerFactory太慢了

1 个答案: