我有一个简单的测试，尝试在其中更新对象，但是合并似乎在执行插入操作而不是更新操作。

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:spring/app-context.xml","classpath:spring/testdb-context.xml"})
public class UserJPATest {
@Test
public void testUpdate() throws Exception {
    System.out.println("update");

    User entity = ObjectManager.USER_DAO.findById(3L);
    entity.setUsername("harryUpdate");

    ObjectManager.USER_DAO.update(entity);

    User selEntity = ObjectManager.USER_DAO.findById(3L);
    Assert.assertEquals(entity.getUsername(),selEntity.getUsername());
}

}

这是我的更新方法

@Override
@Transactional(propagation= Propagation.REQUIRES_NEW)
public T update(T entity) throws Exception {
    try {
        T merged = entityManager.merge(entity);
        return merged;
    } catch (Exception e) {
        e.printStackTrace();
        throw new Exception(e);
    }
}

更新代码

@Override
@Transactional(propagation= Propagation.REQUIRES_NEW)
public T update(T entity) throws Exception {
    try {
        T merged = null;
        BaseEntity baseEntity = null;
        if(entity instanceof BaseEntity){
            baseEntity = (BaseEntity)entity;
            merged = entityManager.find(entityClass, baseEntity.getId());
        }
        merged = entityManager.merge(entity);
        entityManager.flush();
        return merged;
    } catch (Exception e) {
        e.printStackTrace();
        throw new Exception(e);
    }
}

现在，我收到以下错误无法提交JPA事务；嵌套的异常是javax.persistence.RollbackException：标记为rollbackOnly的事务