Hibernate 4 Criteria查询返回空列表

Question

我正在使用Spring 4和Hibernate 4但查询总是返回空列表，即使应该有几行。

这是模型

@DynamicUpdate 
@Table(appliesTo = "comments")
public class Comment {

    @Id @GeneratedValue
    @Column(name = "id")
    private int id;

    @Column(name = "content")
    private String content;

... and some getters and setters ...

这是Spring配置部分

<beans:bean id="dataSource" class="org.apache.commons.dbcp2.BasicDataSource"
    destroy-method="close">
    <beans:property name="driverClassName" value="com.mysql.jdbc.Driver" />
    <beans:property name="url"
        value="jdbc:mysql://mydbroot/circle" />
    <beans:property name="username" value="user" />
    <beans:property name="password" value="password" />
</beans:bean>

<beans:bean id="sessionFactory"
    class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
    <beans:property name="dataSource" ref="dataSource" />
    <beans:property name="configLocation" value="classpath:hibernate.cfg.xml" />
</beans:bean>

<tx:annotation-driven />
<beans:bean id="transactionManager"
    class="org.springframework.orm.hibernate4.HibernateTransactionManager">
    <beans:property name="sessionFactory" ref="sessionFactory" />
</beans:bean>

<beans:bean id="commentDao"
    class="com.hersbitcloud.cancercloud.models.circle.CommentDAO">
    <beans:constructor-arg>
        <beans:ref bean="sessionFactory" />
    </beans:constructor-arg>
</beans:bean>

hibernate.cfg.xml文件

<hibernate-configuration>
<session-factory>
    <property name="dialect">
        org.hibernate.dialect.MySQLDialect
    </property>
    <property name="show_sql">true</property>
</session-factory>

对于DAO

public class CommentDAO {

private SessionFactory sessionFactory;

public CommentDAO(SessionFactory sessionFactory){
    this.sessionFactory = sessionFactory;
}

@Transactional
public List<Comment> GetComments() {

    @SuppressWarnings("unchecked")
    List<Comment> listComment = (List<Comment>) sessionFactory.getCurrentSession()
            .createCriteria(Comment.class).list();

    return listComment;
}

}

在我的控制器中

    @Autowired
private CommentDAO commentDao;

@RequestMapping(value = "/comment", method = RequestMethod.GET) //, produces="application/json")
public int comment() {

    List<Comment> listComments = commentDao.GetComments();
    return listComments.size();

}

始终显示listComments.size()为0。

有什么问题？

我附上数据库的屏幕截图，以显示表名是否正确。

Answer 1

尝试在您的班级CommentDAO中添加以下这些内容，以便更改此内容：

        private SessionFactory sessionFactory;

要：

        @Autowired
        private SessionFactory sessionFactory;

        public void setSessionFactory(SessionFactory sessionFactory){
            this.sessionFactory = sessionFactory;
        }

Answer 2

我认为@Transactional用于对DB执行修改过程。删除@Transactional并尝试一下，

public List<Comment> GetComments() {

@SuppressWarnings("unchecked")
List<Comment> listComment = (List<Comment>) sessionFactory.getCurrentSession()
        .createCriteria(Comment.class).list();

return listComment;
}

将@Transactional放在课堂上方。

如果您想执行动作db，请提供@Transactional(readOnly=false)

Answer 3

@RaphaelRoth感谢您的回复。我通过改变

让一切顺利

@DynamicUpdate 
@Table(appliesTo = "comments")

进入

@Entity
@Table(name="comments")

它们都属于'javax.persistence。*'。