hibernate的对象与数据库表的映射

Customer.java

/**
 * 客户管理的实体类
 * @author zhang
 *CREATE TABLE `cst_customer` (
  `cust_id` bigint(32) NOT NULL AUTO_INCREMENT COMMENT '客户编号(主键)',
  `cust_name` varchar(32) NOT NULL COMMENT '客户名称(公司名称)',
  `cust_source` varchar(32) DEFAULT NULL COMMENT '客户信息来源',
  `cust_industry` varchar(32) DEFAULT NULL COMMENT '客户所属行业',
  `cust_level` varchar(32) DEFAULT NULL COMMENT '客户级别',
  `cust_phone` varchar(64) DEFAULT NULL COMMENT '固定电话',
  `cust_mobile` varchar(16) DEFAULT NULL COMMENT '移动电话',
  PRIMARY KEY (`cust_id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
 */

public class Customer {
	private Long cust_id;
	private String cust_name;
	private String cust_source;
	private String cust_industry;
	private String cust_level;
	private String cust_phone;
	private String cust_mobile;
    //-----省略了get和set方法
}

Customer.hbm.xml----------建议和类放在一起

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<!-- 建立类与表的映射 -->
    <!-- 类的全路径 -->
	<class name="com.hibernate.demo1.Customer" table="cst_customer">
		<!-- 建立类中的属性与表中的主键对应 -->
		<id name="cust_id" column="cust_id">
			<!-- 主键生成策略 -->
			<!-- native increment identity -->
			<generator class="native"/>
		</id>
		
		<!-- 建立类中的普通的属性和表的字段的对应 -->
		<property name="cust_name" column="cust_name"/>
		<property name="cust_source" column="cust_source"/>
		<property name="cust_industry" column="cust_industry"/>
		<property name="cust_level" column="cust_level"/>
		<property name="cust_phone" column="cust_phone"/>
		<property name="cust_mobile" column="cust_mobile"/>
	</class>
</hibernate-mapping>

hibernate.cfg.xml-------------要放在项目的src下

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
	"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
	"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
	<session-factory>
		<!-- 连接数据库的基本参数 -->
		<!-- hibernate-release-5.0.7.Final\project\etc\hibernate.properties -->
		<!-- localhost:3306 -->
		<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
		<property name="hibernate.connection.url">jdbc:mysql:///hibernate_day02</property>
		<property name="hibernate.connection.username">root</property>
		<property name="hibernate.connection.password">password</property>
		<!-- 配置Hibernate的方言 -->
		<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
		
		<!-- ==========可选配置========= -->
		<!-- 打印sql -->
		<property name="hibernate.show_sql">true</property>
		<!-- 格式化sql -->
		<property name="hibernate.format_sql">true</property>
		<!-- 自动创建表 -->
		<property name="hibernate.hbm2ddl.auto">create</property>
		
		<!-- 设置事务隔离级别 -->
		<!-- 
			1 read uncommitted  :脏读、不可重复读、虚读都会发生
			2 read committed    :解决脏读  (oracle默认)
			4 repeatable read   :解决脏读和不可重复读(mysql默认)
			8 serializable      :解决所有问题。串行执行、效率低
		 -->
		<property name="hibernate.connection.isolation">4</property>
		<!-- 配置当前线程绑定的Session -->
		<!-- 不用session.close() -->
		<property name="hibernate.current_session_context_class">thread</property>
		
        <!-- 与表映射的类的全路径，把.换成/ -->
		<mapping resource="com/hibernate/demo1/Customer.hbm.xml"/>
	</session-factory>
</hibernate-configuration>

HibernateDemo1.java

/**
 * hibernate的入门案例
 *
 */
public class HibernateDemo1 {
	
	@Test
	//保存客户的案例
	public void demo1() {
		//1.加载Hibernate的核心配置文件
		Configuration configuration=new Configuration().configure();
		//2.创建一个SessionFactory对象：类似于JDBC连接池
		SessionFactory sessionFactory=configuration.buildSessionFactory();
		//3.通过SessionFactory获取Session对象：类似于JDBC的Connection
		Session session=sessionFactory.openSession();
		//4.手动开启事务
		Transaction transaction= session.beginTransaction();
		//5.编写代码
		
		Customer customer=new Customer();
		customer.setCust_name("王东");
		
		session.save(customer);
		
		//6.事务提交
		transaction.commit();
		//7.资源释放
		session.close();
		sessionFactory.close();
	}
}

简单的增删改查

HibernateDemo2.java

/**
 * hibernate的入门案例
 *
 */
public class HibernateDemo2 {
	
	@Test
	//保存客户的案例
	public void demo1() {
		//1.加载Hibernate的核心配置文件
		Configuration configuration=new Configuration().configure();
		//2.创建一个SessionFactory对象：类似于JDBC连接池
		SessionFactory sessionFactory=configuration.buildSessionFactory();
		//3.通过SessionFactory获取Session对象：类似于JDBC的Connection
		Session session=sessionFactory.openSession();//非线程安全，所以不能放在全局变量
		//4.手动开启事务
		Transaction transaction= session.beginTransaction();
		//5.编写代码
		
		Customer customer=new Customer();
		customer.setCust_name("王二");
		
		session.save(customer);
		
		//6.事务提交
		transaction.commit();
		//7.资源释放
		session.close();
		sessionFactory.close();
	}
	
	@Test
	//查询
	/**
	 * get和load的区别
	 */
	public void demo2() {
		Configuration configuration=new Configuration().configure();
		SessionFactory sessionFactory=configuration.buildSessionFactory();
		Session session=sessionFactory.openSession();
		Transaction tx=session.beginTransaction();
		
		/**
		 * get
		 * 立即加载，执行到这行代码，马上去查询
		 * 查询后返回是真实对象本身
		 * 查询找不到，返回null
		 * 
		 * load
		 * 延迟加载(lazy懒加载)，执行到这行代码不会发送sql语句，当使用这个对象的时候才会发送sql语句
		 * 查询后返回的是代理对象，javassist-3.18.1-GA.jar
		 * 查询找不到，返回ObjectNotFoundException
		 */
		
		//使用get方法查询
//		Customer customer=session.get(Customer.class, 1L);//发送sql语句
//		System.out.println(customer);
		
		//使用load方法查询
		Customer customer=session.load(Customer.class, 2L);
		System.out.println(customer);
		
		tx.commit();
		session.close();
	}
	
	@Test
	//修改操作
	public void demo3() {
		Configuration configuration=new Configuration().configure();
		SessionFactory sessionFactory=configuration.buildSessionFactory();
		Session session=sessionFactory.openSession();
		Transaction tx=session.beginTransaction();
		
		//直接创建对象，进行修改
//		Customer customer=new Customer();
//		customer.setCust_id(1L);
//		customer.setCust_name("王聪");
//		session.update(customer);
		//先查询，再修改（推荐）
		Customer customer=session.get(Customer.class, 1L);
		customer.setCust_name("王小贱");
		session.update(customer);
		
		tx.commit();
		session.close();
	}
	
	@Test
	//删除操作
	public void demo4() {
		Configuration configuration=new Configuration().configure();
		SessionFactory sessionFactory=configuration.buildSessionFactory();
		Session session=sessionFactory.openSession();
		Transaction tx=session.beginTransaction();
		
		//直接创建对象，删除
//		Customer customer=session.get(Customer.class, 1L);
//		customer.setCust_id(1L);
//		session.delete(customer);
		//先查询，在删除(推荐)------
		Customer customer=session.get(Customer.class, 2L);
		session.delete(customer);
		
		tx.commit();
		session.close();
	}
	
	@Test
	//保存或更新
	public void demo5() {
		Configuration configuration=new Configuration().configure();
		SessionFactory sessionFactory=configuration.buildSessionFactory();
		Session session=sessionFactory.openSession();
		Transaction tx=session.beginTransaction();
		
//		Customer customer=new Customer();
//		customer.setCust_name("汪峰");
//		session.saveOrUpdate(customer);
		
		Customer customer=new Customer();
		customer.setCust_id(3L);
		customer.setCust_name("李凤");
		session.saveOrUpdate(customer);
		
		tx.commit();
		session.close();
	}
	
	@Test
	//查询所有
	public void demo6() {
		Configuration configuration=new Configuration().configure();
		SessionFactory sessionFactory=configuration.buildSessionFactory();
		Session session=sessionFactory.openSession();
		Transaction tx=session.beginTransaction();
		//接收HQL：Hibernate Query Language 面向对象的查询语言
//		Query query= session.createQuery("from Customer");
//		List<Customer> list=query.list();
//		for (Customer customer : list) {
//			System.out.println(customer);
//		}
		
		//接收sql
		SQLQuery query=session.createSQLQuery("select * from cst_customer");
		List<Object[]> list=query.list();
		for (Object[] objects : list) {
			System.out.println(Arrays.toString(objects));
		}
		
		tx.commit();
		session.close();
	}
}

获取session的一个工具类

HibernateUtils.java

/**
 * Hibernate的工具类
 *
 */
public class HibernateUtils {

	public static final Configuration cfg;
	public static final SessionFactory sf;
	
	static{
		cfg = new Configuration().configure();
		sf = cfg.buildSessionFactory();
	}
	
	public static Session openSession(){
		return sf.openSession();
	}
	
	public static Session getCurrentSession() {
		return sf.getCurrentSession();//需要配置
	}
}