Hibernate之操作数据库

版权声明：zby https://blog.csdn.net/ZBYTSL/article/details/85448430

配置maven依赖时，hibernate的最新版本

<!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.4.0.Final</version>
    </dependency>

与以前版本的实现代码有些区别，好了！让我们来看看hibernate5.4.0.Final对数据库的操作：

前面的实体类和映射文件，请参考我上一篇文章：https://blog.csdn.net/ZBYTSL/article/details/85373300

新增记录

public class TestInsertStudent {

	public static void main(String[] args) {
		//读取总的配置文件
		Configuration configuration=new Configuration();
		configuration.configure("/hibernate.cfg.xml");
		//创建session工厂
		SessionFactory factory=configuration.buildSessionFactory();
		//打开session
		Session session=factory.openSession();       
		//开启事务
		Transaction transaction=session.beginTransaction();
		//增删改查
		Student student=new Student();
		student.setXm("zby");
		student.setAge(12);
		session.save(student);
		//提交事务
		transaction.commit();
		//不使用连接池，就是关闭连接；使用连接池，session.close()只是把连接放回连接池
		session.close();
	}

}

查询，根据主键查找

public class TsetSelectById {
    //hibernate默认开启一级缓存
	public static void main(String[] args) {
		//读取总的配置文件
		Configuration configuration=new Configuration();
		configuration.configure("/hibernate.cfg.xml");
		//创建session工厂
		SessionFactory factory=configuration.buildSessionFactory();
		//打开session
		Session session=factory.openSession();
		
                //get和load的区别

		/*
		//查询为null 返回null
		Student student=session.get(Student.class, 1);
		if (student==null) {
			System.out.println("查无此人");
		}
		else {
			System.out.println(student.getXm()+"\t"+student.getAge());
		}*/
		
		/*
		 //查询为null 报异常
		Student student=session.load(Student.class, -1);
		if (student==null) {
			System.out.println("查无此人");
		}
		else {
			System.out.println(student.getXm()+"\t"+student.getAge());
		}*/

		
		//表名---》类，字段---》属性，不能用select *
		String hql="from Student where xh=?0";
		//session.createQuery(hql);
		Query<Student> query=session.createQuery(hql,Student.class);
		//第一个？是0，值是1
		query.setParameter(0, 1);
		
		Student student=query.uniqueResult();
		if (student==null) {
			System.out.println("查无此人");
		}
		else {
			System.out.println(student.getXm()+"\t"+student.getAge());
		}
		
		
		
	}

}

修改

public class TestUpdateStudent {

	public static void main(String[] args) {
		//先查找，再修改
		// 1.读取总的配置文件
		Configuration cfg = new Configuration();
		cfg.configure("/hibernate.cfg.xml");

		// 2.创建session工厂
		SessionFactory factory = cfg.buildSessionFactory();

		// 3.打开session
		Session session = factory.openSession();
		
		Student stu = session.get(Student.class, 1);
		if (stu==null)
		{
			System.out.println("查无此人");
		}
		else
		{
			session.getTransaction().begin();
			stu.setXm("子不语");
			session.update(stu);
			session.getTransaction().commit();
		}
				

	}

}