Question

我有一个在数据库上保留大量行的方法，它是这样的：

private EntityManager em;

@PostConstruct
public void init() {
    Map props = new HashMap();
    props.put(PersistenceUnitProperties.JTA_DATASOURCE, dataSource());
    EntityManagerFactory emf = Persistence.createEntityManagerFactory("db1", props);
    em = emf.createEntityManager();
}

public void persistAll(List list) {
    int count = 0;
    for (Object o : list) {

        if (count == 0) {
            em.getTransaction().begin();
        }
        em.persist(o);

        count++;
        if (count >= 500) {
            em.getTransaction().commit();
            count = 0;
        }
    }
    if (count > 0) {
        em.getTransaction().commit();
    }
}

这是我的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="db1" transaction-type="JTA">
        <jta-data-source>db1</jta-data-source>
        <mapping-file>orm.xml</mapping-file>
        <class>com.entities.entity1</class>
        <class>com.entities.entity2</class>
        <class>com.entities.entity3</class>
        <exclude-unlisted-classes>true</exclude-unlisted-classes>
        <validation-mode>NONE</validation-mode>
        <properties>
            <property name="eclipselink.cache.size.default" value="0"/>
            <property name="eclipselink.cache.shared.default" value="false"/>
            <property name="eclipselink.logging.level" value="FINE"/>
        </properties>
    </persistence-unit>
</persistence>

事务在开始时打开并在持久化500个对象后提交，然后再次打开事务，依此类推。此过程将重复，直到所有对象都保持不变。

问题是只有在处理完整个列表后才将对象保存在数据库中，如果我中断执行，即使事务已经提交，也不会保存任何内容。

有没有人知道我做错了什么？

Answer 1

而不是commit，调用flush（）;做点什么

// open the transaction
// start the loop
// for each 500 call entityManager.flush();
// when the loop finishes, call commit() and finish the entityManagfer

commit（）后数据库没有更新

1 个答案: