Question

虽然findAll可以正常工作，但我无法在JPA中保留实体这里。这是JpaDAO


package aop.web.teacher.dao;

import java.lang.reflect.ParameterizedType;
import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceException;
import javax.persistence.Query;

import org.apache.log4j.Logger;
import org.springframework.orm.jpa.JpaCallback;
import org.springframework.orm.jpa.support.JpaDaoSupport;
import org.springframework.stereotype.Repository;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;


public abstract class JpaDAO extends JpaDaoSupport {
 protected Class entityClass;

 private static Logger log = Logger.getLogger(JpaDAO.class);

 @SuppressWarnings("unchecked")
 public JpaDAO() {
  ParameterizedType genericSuperclass = (ParameterizedType) getClass()
    .getGenericSuperclass();
  this.entityClass = (Class) genericSuperclass
    .getActualTypeArguments()[1];
 }

 @Transactional(readOnly = false, propagation = Propagation.REQUIRES_NEW)
 public void persist(E entity) {
  getJpaTemplate().persist(entity);
 }

 @Transactional
 public void remove(E entity) {
  getJpaTemplate().remove(entity);
 }

 @Transactional
 public E merge(E entity) {
  return getJpaTemplate().merge(entity);
 }

 @Transactional
 public void refresh(E entity) {
  getJpaTemplate().refresh(entity);
 }

 @Transactional
 public E findById(K id) {
  return getJpaTemplate().find(entityClass, id);
 }

 @Transactional
 public E flush(E entity) {
  getJpaTemplate().flush();
  return entity;
 }

 @SuppressWarnings("unchecked")
 @Transactional
 public List findAll() {
  Object res = getJpaTemplate().execute(new JpaCallback() {

   public Object doInJpa(EntityManager em) throws PersistenceException {
    Query q = em.createQuery("SELECT h FROM "
      + entityClass.getName() + " h");
    return q.getResultList();
   }

  });

  return (List) res;
 }

 @SuppressWarnings("unchecked")
 @Transactional
 public Integer removeAll() {
  return (Integer) getJpaTemplate().execute(new JpaCallback() {

   public Object doInJpa(EntityManager em) throws PersistenceException {
    Query q = em.createQuery("DELETE FROM " + entityClass.getName()
      + " h");
    return q.executeUpdate();
   }

  });
 }

}

这是TestDao类


package aop.web.teacher.dao;

import java.util.Date;
import java.util.List;

import javax.annotation.PostConstruct;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.PersistenceContext;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import org.springframework.stereotype.Service;



import aop.web.teacher.rmodels.Teachermaster;

@Service
@Repository
public class TestDaoImpl extends JpaDAO implements TestDao {

 @Autowired
 EntityManagerFactory entityManagerFactory;

 @PersistenceContext
 private EntityManager em;

 @PostConstruct
 public void init() {
  super.setEntityManagerFactory(entityManagerFactory);
 }

 public int saveTeacher() {
  List teacherList = findAll();
  Teachermaster m1 = teacherList.get(0);
  logger.info("Found " + m1.getId() + " and " + m1.getRace());
  m1.setRace(m1.getRace() + "::" + System.currentTimeMillis());
  logger.info("New " + m1.getId() + " and " + m1.getRace());
  persist(m1);
  return 0;
 }

}

这是spring context xml

http://pastebin.com/pKqzW9h1

这里的findAll有效但是当我们改变教师的属性时然后坚持或合并似乎并没有拯救实体...... 如果我们冲洗它，我们会得到异常

javax.persistence.TransactionRequiredException: no transaction is in progress

请告知

Answer 1

Spring使用基于代理的AOP，因此当从同一个类调用方法时，不应用方面（包括事务方面）。

一般来说

@Transactional注释通常应放在服务方法而不是DAO方法
您的saveTeacher()看起来像服务方法，最好将其放在单独的服务类中并注释为@Transactional
persist()中不需要saveTeacher() - 对持久对象所做的更改应自动保存
注意动态代理与目标类代理的区别（关于TestDao） - 请参阅下面的链接

另见：

Answer 2

从测试类调用persist()时，您正在调用本地方法。这样就不会调用会创建事务的代理，因此您对persist()的调用没有事务。

正确执行此操作的方法是让测试类不扩展测试对象但是将其注入。这样，将触发代理并创建事务。

顺便说一句，我必须补充一点，我发现你的班级设计有点特别。我可以建议创建如下结构吗？

DAO界面：

public interface FooDao {
    void persist(Foo foo);
    // ...
}

DAO实施：

public class FooDaoImpl implements FooDao {
    @PersistenceContext
    private EntityManager entityManager;

    @Transactional
    public void persist(Foo foo) {
        entityManager.persist(foo);
    }
}

测试类：

@RunWith(SpringJunit4ClassRunner.class)
@ContextConfiguration(...)
public class FooDaoTest {
    @Autowired
    private FooDao fooDao;

    @Test
    public void testPersist() {
        // do some testing
    }
}

如果您愿意，您可以将DAO实现中的大部分逻辑提取到通用超类中。

在春季3，无法在JPA中坚持实体

2 个答案: