10-主鍵的生成器
hibernate是根據映射文件的主鍵生成器生成主鍵噠,自己設置的主鍵不起作用
<!-- 主鍵的產生器,就該告訴hibernate容器用什麼樣的方式產生主鍵-->
<generator class="increment"></generator>
import org.hibernate.Session; import org.hibernate.Transaction; import org.junit.Test; public class GeneratorTest extends ConfigUtil{ /** * Hibernate: select max(pid) from Person Hibernate: insert into Person (pname, psex, pid) values (?, ?, ?) 說明: 1、主鍵的類型必須是數字 2、主鍵的生成是由hibernate內部完成的,程序員不需要干預 3、這種生成機制效率比較低 */ @Test public void testIncrement(){ Session session = sessionFactory.openSession(); Transaction transaction = session.beginTransaction(); Person person = new Person(); person.setPname("班長3"); person.setPsex("女"); /**save的參數必須持久化對象*/ session.save(person); transaction.commit(); session.close(); } /* * Hibernate: insert into Person (pname, psex) values (?, ?) * 說明 * 1、新的主鍵的產生是由數據庫完成的,並不是由hibernate或者程序員完成的 * 2、該表必須支持自動增長機制 * 3、效率比較高 */ @Test public void testIdentity(){ Session session = sessionFactory.openSession(); Transaction transaction = session.beginTransaction(); Person person = new Person(); person.setPname("班長"); person.setPsex("女"); /** * 參數必須持久化對象 */ session.save(person); transaction.commit(); session.close(); } /** * 由程序員手寫設置主鍵 */ @Test public void testAssigned(){ Session session = sessionFactory.openSession(); Transaction transaction = session.beginTransaction(); Person person = new Person(); person.setPid(4L); person.setPname("班長"); person.setPsex("女"); session.save(person); transaction.commit(); session.close(); } /** * 1、UUID是由hibernate內部生成的,主鍵的類型是String * 2、主鍵的類型必須是字符串 */ @Test public void testUUID(){ Session session = sessionFactory.openSession(); Transaction transaction = session.beginTransaction(); Person person = new Person(); person.setPname("班長"); person.setPsex("女"); session.save(person); transaction.commit(); session.close(); } /** * hibernate內部是根據主鍵生成器來生成主鍵的,在客戶端設置主鍵不一定起作用,在assigned的時候起作用 */ @Test public void testIdentity_ID(){ Session session = sessionFactory.openSession(); Transaction transaction = session.beginTransaction(); Person person = new Person(); person.setPid(1L); person.setPname("aa"); person.setPsex("aa"); session.save(person); transaction.commit(); session.close(); } }