Hibernate Part 二：单表CRUD

Hibernate Part 2：单表CRUD

使用Hibernate实现单表CRUD，数据库使用MySQL

建立customer表

create database test;
create table customer (
	id int primary key auto_increment,
	name varchar(20),
	age int,
	city varchar(20)
);

创建JavaBean对象

package rock.lee.bean;

import java.io.Serializable;

public class Customer implements Serializable{
	private static final long serialVersionUID = -3229680950625733244L;
	private Integer id;
	private String name;
	private Integer age;
	private String city;
	
	public Customer() {
		super();
	}
	public Customer(String name, Integer age, String city) {
		super();
		this.name = name;
		this.age = age;
		this.city = city;
	}
	
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Integer getAge() {
		return age;
	}
	public void setAge(Integer age) {
		this.age = age;
	}
	public String getCity() {
		return city;
	}
	public void setCity(String city) {
		this.city = city;
	}
	@Override
	public String toString() {
		return "Customer [id=" + id + ", name=" + name + ", age=" + age+ ", city=" + city + "]";
	}
}

Hibernate是一个Object Relational Mapping框架，这里采用配置文件的形式实现JavaBean对象映射到关系型数据表

编写hbm.xml文件，在JavaBean所在的包下建立Customer.hbm.xml文件，引入hibernate3.jar中org/hibernate/hibernate-mapping-3.0.dtd里的DTD约束

<?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>
	<!-- 
			name:Bean的完整的类名 
			table:与Bean所要映射的数据库表名 
			catalog: 数据库库名 
	-->
	<class name="rock.lee.bean.Customer" table="customer" catalog="test">
		<!-- 
				id:标签用于配置主键 
				name: Customer类中的主键属性 
				column:数据库中所对应的列名 
				type:属性的类型 
		-->
		<id name="id" column="id" type="int">
			<!-- 
					generator标签用于配置主键的生成策略 
			-->
			<generator class="native"></generator>
		</id>
		<!-- 
				property标签用于配置其它Bean属性所对应的表列明
		 -->
		<property name="name" column="name" type="java.lang.String"></property>
		<property name="age" column="age" type="int"></property>
		<property name="city" column="city" type="java.lang.String"></property>
	</class>
</hibernate-mapping>

<proterty>标签中type的取值

Hibernate Part 二：单表CRUD

编写Hibernate核心配置文件hibernate.cfg.xml，引入hibernate3.jar 中/org/hibernate/hibernate-configuration-3.0.dtd 的配置文件约束

<!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>
		<!-- 配置数据库连接参数 -->
		<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
		<property name="hibernate.connection.url">jdbc:mysql:///test</property>
		<property name="hibernate.connection.username">root</property>
		<property name="hibernate.connection.password">root</property>
		<!-- 配置数据库方言 -->
		<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
		<!-- 向控制台打印SQL语句 -->
		<property name="show_sql">true</property>
		<!-- SQL语句格式化打印 -->
		<property name="hibernate.format_sql">true</property>
		<!-- 可以自动根据类生成DDL 建表语言，完成自动建表 -->
		<property name="hibernate.hbm2ddl.auto">update</property>
		<!-- 加载 hbm 映射文件 -->
		<mapping resource="rock/lee/bean/Customer.hbm.xml" />
	</session-factory>
</hibernate-configuration>

com.mysql.jdbc.Driverjdbc:mysql:///testrootrootorg.hibernate.dialect.MySQLDialecttruetrueupdate
编写测试用例

CRUD的代码结构

	@Test
	public void test(){
		Configuration configuration = new Configuration().configure();// 实例化配置对象，加载配置文件 hibernate.cfg.xml
		SessionFactory sessionFactory = configuration.buildSessionFactory();// 创建Session连接工厂
		Session session = sessionFactory.openSession();//创建Session
		Transaction transaction = session.beginTransaction();//开启事物
		//.....编写CRUD代码
		transaction.commit();//提交事务
		session.close();//关闭session
		sessionFactory.close();//关闭session工厂
	}

这段代码的流程

Hibernate Part 二：单表CRUD

保存：

@Test
	public void testSave(){
		Configuration configuration = new Configuration().configure();
		SessionFactory sessionFactory = configuration.buildSessionFactory();
		Session session = sessionFactory.openSession();
		Transaction transaction = session.beginTransaction();
		
		Customer c = new Customer("小明",18,"北京");
		session.save(c);
		
		transaction.commit();
		session.close();
		sessionFactory.close();
	}

通过ID获取数据：

@Test
	public void testSave(){
		Configuration configuration = new Configuration().configure();
		SessionFactory sessionFactory = configuration.buildSessionFactory();
		Session session = sessionFactory.openSession();
		Transaction transaction = session.beginTransaction();
		
		Customer c = new Customer("小明",18,"北京");
		session.save(c);
		
		transaction.commit();
		session.close();
		sessionFactory.close();
	}

更新数据：

	@Test
	public void testUpdate(){
		Configuration configuration = new Configuration().configure();// 实例化配置对象，加载配置文件 hibernate.cfg.xml
		SessionFactory sessionFactory = configuration.buildSessionFactory();// 创建Session连接工厂
		Session session = sessionFactory.openSession();//创建Session
		Transaction transaction = session.beginTransaction();//开启事物

		Customer customer = new Customer();
		customer.setId(1);
		customer.setName("小丽");
		customer.setAge(25);
		customer.setCity("上海");
		session.update(customer);

		transaction.commit();//提交事务
		session.close();//关闭session
		sessionFactory.close();//关闭session工厂
	}

HQL查询所有数据：

	@Test
	public void testFindAllByHQL(){
		Configuration configuration = new Configuration().configure();// 实例化配置对象，加载配置文件 hibernate.cfg.xml
		SessionFactory sessionFactory = configuration.buildSessionFactory();// 创建Session连接工厂
		Session session = sessionFactory.openSession();//创建Session
		Transaction transaction = session.beginTransaction();//开启事物

		String hql = " from Customer";
		Query query = session.createQuery(hql);
		@SuppressWarnings("unchecked")
		List <Customer>list = query.list();
		System.out.println(list);
		
		transaction.commit();//提交事务
		session.close();//关闭session
		sessionFactory.close();//关闭session工厂
	}

SQL查询所有数据：

@Test
	public void testFindALllBySQL(){
		Configuration configuration = new Configuration().configure();// 实例化配置对象，加载配置文件 hibernate.cfg.xml
		SessionFactory sessionFactory = configuration.buildSessionFactory();// 创建Session连接工厂
		Session session = sessionFactory.openSession();//创建Session
		Transaction transaction = session.beginTransaction();//开启事物

		String sql = "select * from customer";
		SQLQuery query = session.createSQLQuery(sql);
		@SuppressWarnings("unchecked")
		List<Object[]> list = query.list();
		for (Object[] objs : list) {
			System.out.println(Arrays.toString(objs));
		}
		
		transaction.commit();//提交事务
		session.close();//关闭session
		sessionFactory.close();//关闭session工厂
	}

通过ID删除数据：

	@Test
	public void testDelete(){
		Configuration configuration = new Configuration().configure();// 实例化配置对象，加载配置文件 hibernate.cfg.xml
		SessionFactory sessionFactory = configuration.buildSessionFactory();// 创建Session连接工厂
		Session session = sessionFactory.openSession();//创建Session
		Transaction transaction = session.beginTransaction();//开启事物

		Customer customer = new Customer();
		customer.setId(1);
		session.delete(customer);
		
		transaction.commit();//提交事务
		session.close();//关闭session
		sessionFactory.close();//关闭session工厂
	}

通过操作Customer对象，实现了对数据表的CRUD操作，其中最为核心的一个Hibernate接口是Session接口，所有的CRUD操作都是通过Session接口完成的。

测试用例中的一些代码并不合理，只是为了说明Hibernate单表CRUD中所使用到的API。

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