Question

我想将实体序列化为SQL查询字符串并将其保存到.txt文件中，以便以后能够将其写入数据库。无论SQL方言如何，我都需要解决方案才能工作，所以我想使用Hibernate。

Hibernate可以做到吗？你能给我一个线索或教程，我怎么能做到这一点？

我们假设我们有一个实体：

@Entity  
public class Project {
       @Id
       @GeneratedValue(strategy = GenerationType.SEQUENCE)
       private Long id;
       private String name;

       //... setters, getters and constructor
}

我想将一些实体序列化为SQL语句字符串，如下所示：

INSERT INTO project (name)
VALUES ('SQL Convertion Project');
INSERT INTO project (name)
VALUES ('DB Migration');
INSERT INTO project (name)
VALUES ('Stackoverflow is cool');

Answer 1

我找到了解决方案。我希望它会对某人有所帮助。

下面的代码使用Hibernate实体persister获取实体Project的插入和更新查询。如果需要，我可以注入查询参数并将查询写入文件。

仅使用Hibernate框架：

Configuration configuration = new Configuration().configure();
StandardServiceRegistryBuilder builder = new StandardServiceRegistryBuilder().
        applySettings(configuration.getProperties());
SessionFactory sessionFactory = configuration.buildSessionFactory(builder.build());

ClassMetadata hibernateMetadata = sessionFactory.getClassMetadata("com.mypackage.Project ");
if (hibernateMetadata == null){
    return;
}

if (hibernateMetadata instanceof AbstractEntityPersister) {
    AbstractEntityPersister persister = (AbstractEntityPersister) hibernateMetadata;

    for (Method method : persister.getClass().getSuperclass().getDeclaredMethods()) {
        if (method.getName().equalsIgnoreCase("getSQLInsertStrings")) {
            ReflectionUtils.makeAccessible(method);
            Object insertQueries = ReflectionUtils.invokeMethod(method, persister);

            for (String queryText : (String []) insertQueries) {
                System.out.println(queryText);
            }
        }

        if (method.getName().equalsIgnoreCase("getSQLUpdateStrings")) {
            ReflectionUtils.makeAccessible(method);
            Object insertQueries = ReflectionUtils.invokeMethod(method, persister);

            for (String queryText : (String []) insertQueries) {
                System.out.println(queryText);
            }
        }
    }
}

使用Hibernate + Spring

ApplicationContext ctx = new ClassPathXmlApplicationContext（ “applicationContext.xml中”）;

EntityManager em = ((EntityManagerFactory) ctx.getBean("entityManagerFactory")).createEntityManager();
try {
    Session session = em.unwrap(Session.class);

    ClassMetadata hibernateMetadata = session.getSessionFactory().getClassMetadata("com.mypackage.Project");
    if (hibernateMetadata == null){
        return;
    }
    if (hibernateMetadata instanceof AbstractEntityPersister) {
        AbstractEntityPersister persister = (AbstractEntityPersister) hibernateMetadata;

        for (Method method : persister.getClass().getSuperclass().getDeclaredMethods()) {
            if (method.getName().equalsIgnoreCase("getSQLInsertStrings")) {
                ReflectionUtils.makeAccessible(method);
                Object insertQueries = ReflectionUtils.invokeMethod(method, persister);

                for (String queryText : (String []) insertQueries) {
                    System.out.println(queryText);
                }
            }

            if (method.getName().equalsIgnoreCase("getSQLUpdateStrings")) {
                ReflectionUtils.makeAccessible(method);
                Object insertQueries = ReflectionUtils.invokeMethod(method, persister);

                for (String queryText : (String []) insertQueries) {
                    System.out.println(queryText);
                }
            }
        }

    }
}
finally {
    if (em != null) {
        em.close();
    }
}

Hibernate将sql保存到文件中

1 个答案: