1、创建Hibernate配置文件(hibernate.cfg.xml)
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"-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
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| 1）问题：生成cfg.xml时候弹出右下角内容，然后按finish一直无反应怎么办？？ 答：hibernate版本问题，就是第三行Hibernate version那个选择低一点的版本 我看Jar包是4.3.x的，我选了4.3的就OK了 |
2、创建持久化类
| package csah.com.cnblogs.www;
import java.util.Date;
public class News { private Integer id; private String title; private String author; private Date date; public Date getDate() { return date; } public News(String title, String author, Date date) { super(); this.title = title; this.author = author; this.date = date; } public void setDate(Date date) { this.date = date; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } public String getAuthor() { return author; } public void setAuthor(String author) { this.author = author; } public News() { } @Override public String toString() { return "News [id=" + id + ", title=" + title + ", author=" + author + ", date=" + date + "]"; } } |
3、创建对象-关系映射文件(*.hbm.xml)
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"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
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| 1）问题：ids for this class must be manually assigned before calling save(): csah.com.cnblogs.www.News 答：我们只需要将 |
4、通过Hibernate API编写访问数据库代码
| package csah.com.cnblogs.www;
import static org.junit.jupiter.api.Assertions.*;
import java.sql.Date;
import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.cfg.Configuration; import org.hibernate.service.ServiceRegistry; import org.hibernate.service.ServiceRegistryBuilder; import org.junit.jupiter.api.Test;
import csah.com.cnblogs.www.*;
class HibernateTest {
@Test public void test() {
System.out.println("test1...");
//1. 创建一个 SessionFactory 对象 SessionFactory sessionFactory = null; System.out.println("test2...");
//1). 创建 Configuration 对象: 对应 hibernate 的基本配置信息和 对象关系映射信息 Configuration configuration = new Configuration().configure(); System.out.println("test3...");
//4.0 之前这样创建 // sessionFactory = configuration.buildSessionFactory();
//2). 创建一个 ServiceRegistry 对象: hibernate 4.x 新添加的对象 //hibernate 的任何配置和服务都需要在该对象中注册后才能有效. ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()) .buildServiceRegistry(); System.out.println("test4...");
//3). sessionFactory = configuration.buildSessionFactory(serviceRegistry); System.out.println("test5...");
//2. 创建一个 Session 对象 Session session = sessionFactory.openSession(); System.out.println("test6...");
//3. 开启事务 Transaction transaction = session.beginTransaction(); System.out.println("test7...");
//4. 执行保存操作 News news = new News("java", "ATGUIGU", new Date(new java.util.Date().getTime())); System.out.println("test8...");
session.save(news); System.out.println("test9...");
//5. 提交事务 transaction.commit(); System.out.println("test10...");
//6. 关闭 Session session.close(); System.out.println("test11...");
//7. 关闭 SessionFactory 对象 sessionFactory.close(); System.out.println("test12..."); }
} |
注意：上面的多个system.out.println()可以测试代码运行到哪一部分中断，如如果System.out.println("test9...");没有输出，那么我们只要找session.save(news)的问题即可。
| 1）问题：org.hibernate.InvalidMappingException: Could not parse mapping document from resource com/cnblogs/com/CSAH/News.hbm.xml java.lang.ClassNotFoundException: com.nblogs.com.CSAH.News 答：在News.hbm.xml中 class中的路径出现错误 没有找到'com.nblogs.com.CSAH.News'
2）问题：org.hibernate.MappingNotFoundException: resource: com/cnblogs/com/CSAH/News.hbm.xml not found 答：指定关联的 .hbm.xml 文件路径没有找到
3）问题：Duplicate entry 'java' for key 2 答：插入的数据已经存在 |