hibernate hql查询个别字段映射到实体类_Hibernate 运行期动态模型、动态实体建表、动态字段...

在页面上创建表模型添加修改字段。涉及到动态生成表结构，动态生成模型实体类动态查询表字段等等，经过调研发现hibernate在这方面是很方便的，调用内置API就能完成系列操作，下面贴出核心代码：

/** * @author cjbi */public class DynamicDdlTest {    @Autowired    private EntityManagerFactory entityManagerFactory;/** * 运行期的持久化实体没有必要一定表示为像POJO类或JavaBean对象那样的形式。 * Hibernate也支持动态模型在运行期使用Map)和象DOM4J的树模型那样的实体表示。 * 使用这种方法，你不用写持久化类，只写映射文件就行了。**/    public static final String XML_MAPPING = "<?xml version="1.0" encoding="UTF-8"?>" +            " +            "        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">" +            "" +            "    " +            "        " +            "            " +            "        " +            "        " +            "        " +            "        " +            "        " +            "        " +            "    " +            "";    @Test    public void testDynamicDdl() {        SessionFactory sessionFactory =  entityManagerFactory.unwrap(SessionFactory.class);        StandardServiceRegistry serviceRegistry = sessionFactory.getSessionFactoryOptions().getServiceRegistry();        MetadataSources metadataSources = new MetadataSources(serviceRegistry);        sessionFactory.getSessionFactoryOptions();        //读取映射文件        metadataSources.addInputStream(new ByteArrayInputStream(XML_MAPPING.getBytes()));        Metadata metadata = metadataSources.buildMetadata();        //创建数据库Schema,如果不存在就创建表,存在就更新字段,不会影响已有数据        SchemaExport schemaExport = new SchemaExport();        schemaExport.createOnly(EnumSet.of(TargetType.DATABASE), metadata);                Metadata metadata = metadataSources.buildMetadata();        //创建会话工厂        SessionFactory newSessionFactory = metadata.buildSessionFactory();        //保存对象        Session newSession = newSessionFactory.openSession();        for (int i = 0; i < 100; i++) {            Map student = new HashMap<>();            student.put("username", "张三" + i);            student.put("password", "adsfwr" + i);            student.put("sex", i % 2 == 0 ? "male" : "female");            student.put("age", i);            student.put("birthday", new Date());            newSession.save("Student", student);        }        //查询所有对象        Query query = newSession.createQuery("from Student");        List list = query.getResultList();        System.out.println("resultList: " + list);        //关闭会话        newSession.close();    }}