Hibernate如何返回JSON值？

<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-core</artifactId>
    <version>5.x.x</version>
</dependency>

@Entity
@Table(name = "user")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

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

    // getter和setter方法
}

<hibernate-configuration>
    <session-factory>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/database_name</property>
        <property name="hibernate.connection.username">username</property>
        <property name="hibernate.connection.password">password</property>
        <property name="hibernate.show_sql">true</property>
        <property name="hibernate.format_sql">true</property>

        <mapping class="com.example.User" />

    </session-factory>
</hibernate-configuration>

SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
Session session = sessionFactory.openSession();

Query query = session.createQuery("FROM User");
List<User> users = query.list();

// 使用JSON库将查询结果转换为JSON字符串
String json = new Gson().toJson(users);

session.close();