Hibernate文件配置
- 2019 年 10 月 7 日
- 笔记
ORM : 对象关系映射
映射需要通过XML的配置文件来完成，这个配置文件尽量统一（xxx.hbm.xml） Hibernate核心的配置：必须的配置、可选的配置、映射文件的引入
Configuration的作用：1.加载核心配置文件 2.加载映射文件 SessionFactory：内部维护了Hibernate的连接池和Hibernate的二级缓存，是线程安全的对象，一个项目创建一个对象即可 Session：代表Hibernate和数据库的连接对象，不是线程安全的，所以不能定义成全局的变量 Transaction：Hibernate中管理事务的对象
文件结构
工具类
import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; 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(); } }
对象类
public class Customer { private int id; private String name; private String source; private String industry; private String level; private String phone; private String mobile; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getSource() { return source; } public void setSource(String source) { this.source = source; } public String getIndustry() { return industry; } public void setIndustry(String industry) { this.industry = industry; } public String getLevel() { return level; } public void setLevel(String level) { this.level = level; } public String getPhone() { return phone; } public void setPhone(String phone) { this.phone = phone; } public String getMobile() { return mobile; } public void setMobile(String mobile) { this.mobile = mobile; } @Override public String toString() { return "Customer{" + "id=" + id + ", name='" + name + ''' + ", source='" + source + ''' + ", industry='" + industry + ''' + ", level='" + level + ''' + ", phone='" + phone + ''' + ", mobile='" + mobile + ''' + '}'; } }
映射配置文件
<?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--> <!--如果类中的属性名和表中的字段名一直，column可以省略--> <class name="com.jinke.hibernate.Customer" table="customer"> <!--建立类中的属性与表中的主键对应--> <id name="id" column="id"> <generator class="native"/> </id> <!--建立类中的普通属性和标的字段的对应--> <property name="name" column="name" length="32" type="string" not-null="true" unique="true"/> <property name="source" column="source"/> <property name="industry" column="industry"/> <property name="level" column="level"/> <property name="phone" column="phone"/> <property name="mobile" column="mobile"/> </class> </hibernate-mapping>
总配置类
<?xml version='1.0' encoding='utf-8'?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN" "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <!--必须配置===============--> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/spring_database?characterEncoding=utf8 </property> <property name="hibernate.connection.username">root</property> <property name="hibernate.connection.password">1234</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">update</property> <!--映射文件的引用===============--> <mapping resource="com/jinke/hibernate/Customer.hbm.xml"/> </session-factory> </hibernate-configuration>
测试类
import com.jinke.hibernate.utils.HibernateUtils; import org.hibernate.Session; import org.hibernate.Transaction; import org.hibernate.query.NativeQuery; import org.hibernate.query.Query; import org.junit.Test; import java.util.Arrays; import java.util.List; public class HibernateDemo1 { @Test public void demo() { /* //1.加载hibernate核心配置文件 Configuration configuration = new Configuration().configure(); //2.创建一个sessionfactory对象：类似于jdbc中连接池 SessionFactory sessionFactory = configuration.buildSessionFactory(); //3.通过sessionFactory获取到session对象：类似于jdbc中connection Session session = sessionFactory.openSession();*/ Session session = HibernateUtils.openSession(); //4.手动开启事务 Transaction transaction = session.beginTransaction(); //5.编写代码 Customer customer = new Customer(); customer.setName("王东"); //保存 session.save(customer); //6.事务提交 transaction.commit(); //7.资源释放 session.close(); /*sessionFactory.close();*/ } /** * get方法：（一般用这种） * 采用立即加载，执行到这行代码的时候，马上发送SQL语句去查询 * 查询后返回的是真是对象本身 * 查询一个找不到的对象会返回null * <p> * load方法： * 采用延迟加载（懒加载），执行到这行代码的时候，不会发送SQL语句，当真正使用项目的时候才会发送SQL语句 * 查询后返回的是代理对象 * 查询一个找不到的对象会抛出一个异常 */ @Test //查询 public void demo2() { Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //使用get方法 Customer customer = session.get(Customer.class, 1); System.out.println(customer); //使用load方法 /*Customer load = session.load(Customer.class, 2); System.out.println(load);*/ tx.commit(); session.close(); } @Test //修改 public void demo3() { Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //直接创建对象，进行修改 /*Customer customer = new Customer(); customer.setId(1); customer.setName("李达"); session.update(customer);*/ //先查询，再修改（一般用这种） Customer customer = session.get(Customer.class, 1); customer.setName("张三"); session.update(customer); tx.commit(); session.close(); } @Test //删除 public void demo4() { Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //直接创建对象，进行删除 /*Customer customer = new Customer(); customer.setId(1); session.delete(customer);*/ //先查询，再删除(一般用这种) 级联删除 Customer customer = session.get(Customer.class, 1); session.delete(customer); tx.commit(); session.close(); } @Test //保存或更新 public void demo5() { Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); Customer customer = new Customer(); /*customer.setName("李飞"); session.saveOrUpdate(customer);*/ customer.setId(3); customer.setName("如花"); session.saveOrUpdate(customer); tx.commit(); session.close(); } @Test //查询所有 public void demo6() { Session session = HibernateUtils.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： NativeQuery sqlQuery = session.createSQLQuery("select * from customer"); List<Object[]> sqlList = sqlQuery.list(); for (Object[] objects : sqlList) { System.out.println(Arrays.toString(objects)); } tx.commit(); session.close(); } }
结果在MySql Workbench里看
