记录Hibernate的搭建过程

Hibernate是ssh框架中的数据库部分，它采用的是ORM的思想即通过操作实体类对象去操作数据库。
PART_ONE:
记录下配置Hibernate的步骤：
1.下载Hibernate的jar包
这个可以自行到Hibernate官网中下载最新完整jar包

image.png

2.编写需要操作的实体类，我这里是客户类(Customer.class)
Customer.class:

public class Customer implements Serializable{

    private static final long serialVersionUID = 1L;
    private Integer id;
    private String name;
    private String gender;
    private Integer age;
    private String level;
    
    private Set<Order> orders = new HashSet<Order>();
    private Set<Role> roles = new HashSet<Role>();
    
    private Card card;
    
    
    
    
    public Card getCard() {
        return card;
    }
    public void setCard(Card card) {
        this.card = card;
    }
    public Set<Role> getRoles() {
        return roles;
    }
    public void setRoles(Set<Role> roles) {
        this.roles = roles;
    }
    public Set<Order> getOrders() {
        return orders;
    }
    public void setOrders(Set<Order> orders) {
        this.orders = orders;
    }
    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 String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    public String getLevel() {
        return level;
    }
    public void setLevel(String level) {
        this.level = level;
    }
    @Override
    public String toString() {
        return "Customer [id=" + id + ", name=" + name + ", gender=" + gender
                + ", age=" + age + ", level=" + level + "]";
    }
    
}

3.创建客户类对应的hibernte对应数据库信息的xml（Customer.hbm.xml）,这个文件与实体类处于同一位置下。
Customer.hbm.xml:

<?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 package="caixiaohao.entiy">   <!--所在类的包位置-->
 <class name="Customer" table="t_customer">
     <id name="id" column="c_id">
         <generator class="native"></generator>
     </id>
     <property name="name" column="c_name"></property>
     <property name="gender" column="c_gender"></property>
     <property name="age" column="c_age"></property>
     <property name="level" column="c_level"></property>
     
     <!--一对多配置-->
     <set name="orders">
         <key column="cust_id"></key>
         <one-to-many class="Order"/>
     </set>
     
     <!--多对多关系配置-->
     <set name="roles" table="t_user_roles">
         <key column="user_id"></key>
         <many-to-many class="Role" column="role_id"></many-to-many>
     </set>
     
     <!--一对一配置-->
     <one-to-one name="card" class="Card"></one-to-one>
     
 </class>


</hibernate-mapping>    

4.创建Hibernate的核心配置文件（hibernate.cfg.xml）,这个文件放置在项目的src下。
hibernate.cfg.xml:

<?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>
        <!-- 1.连接数据库参数 -->
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/hibernatelearn</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.connection.password"></property>
        
        <!-- Hibernate整合c3p0 -->
        <property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
        <!-- c3p0详细配置 -->
        <property name="c3p0.min_size">10</property>
        <property name="c3p0.max_size">20</property>
        
        <!-- hibernate方言 -->
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        
        
        <!-- 2.hibernate扩展参数 -->
        <property name="hibernate.show_sql">true</property>
        <property name="hibernate.format_sql">true</property>
        <property name="hibernate.hbm2ddl.auto">update</property>
        
        
        <!-- *.hbm.xml文件 -->
        <mapping resource="caixiaohao/entiy/Customer.hbm.xml"/>
        <mapping resource="caixiaohao/entiy/Order.hbm.xml"/>
        <mapping resource="caixiaohao/entiy/Role.hbm.xml"/>
        <mapping resource="caixiaohao/entiy/Card.hbm.xml"/>
    </session-factory>

</hibernate-configuration>

5.将初始化的工作写成一个Hibernate的工具类（HibernateUtil.class）
HibernateUtil.class:

package Util;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class HibernateUtil {
    public static Configuration cfg = null;
    public static SessionFactory factory = null;
    
    static {
        cfg = new Configuration();
        cfg.configure();
        factory = cfg.buildSessionFactory();
    }
    
    public static Session getSession() {
        return factory.openSession();
    }
    

}

6.可以进行对数据库的操作，在test类中测试。

@Test
    public void testSaveOrder() {
        Customer test = new Customer();
        test.setName("我是个测试);
        Session session = HibernateUtil.getSession();
        Transaction tx = session.beginTransaction();
        session.save(test);
        tx.commit();
        session.close();
    }

PART_TWO:
对数据进行CRUD的操作，Hibernate提供了三种方式分别是Hql,criteria,Sql.
Hql方式的演示:

package doTest;
import java.util.ArrayList;
import java.util.List;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.jupiter.api.Test;

import Util.HibernateUtil;
import caixiaohao.entiy.Customer;

public class HqlTest {
    
    //全表查询
    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction tx = session.beginTransaction();
        Query query = session.createQuery("from Customer");
        List<Customer> customers = query.list();
        for(Customer c : customers) {
            System.out.println(c);
        }
        tx.commit();
        session.close();    
    }
    
    //条件查询
    @Test
    public void test2() {
        Session session = HibernateUtil.getSession();
        Transaction tx = session.beginTransaction();
        Query query = session.createQuery("from Customer where c_name like '%胖%' ");
        List<Customer> customers = query.list();
        for(Customer c : customers) {
            System.out.println(c);
        }
        tx.commit();
        session.close();    
    }
    
    //条件查询2
        @Test
        public void test3() {
            Session session = HibernateUtil.getSession();
            Transaction tx = session.beginTransaction();
            Query query = session.createQuery("from Customer where c_name like ? ");
            query.setParameter(0, "%胖%");
            List<Customer> customers = query.list();
            for(Customer c : customers) {
                System.out.println(c);
            }
            tx.commit();
            session.close();    
        }
        
        //条件查询3
        @Test
        public void test4() {
            Session session = HibernateUtil.getSession();
            Transaction tx = session.beginTransaction();
            Query query = session.createQuery("from Customer where c_name like :name ");
            query.setParameter("name", "%豪%");
            List<Customer> customers = query.list();
            for(Customer c : customers) {
                System.out.println(c);
            }
            tx.commit();
            session.close();    
        }   
        
        //分页查询
        @Test
        public void test5() {
            Session session = HibernateUtil.getSession();
            Transaction tx = session.beginTransaction();
            Query query = session.createQuery("from Customer");
            query.setFirstResult(0);
            query.setMaxResults(4);
            List<Customer> customers = query.list();
            for(Customer c : customers) {
                System.out.println(c);
            }
            tx.commit();
            session.close();    
        }
        
        //聚合查询
        @Test
        public void test6() {
            Session session = HibernateUtil.getSession();
            Transaction tx = session.beginTransaction();
            Query query = session.createQuery("select count(*) from Customer");
            Long count = (Long) query.uniqueResult();
            System.out.println(count);
//          List<Customer> customers = query.list();
//          for(Customer c : customers) {
//              System.out.println(c);
//          }
            tx.commit();
            session.close();    
        }
        
        //投影查询
        @Test
        public void test7() {
            Session session = HibernateUtil.getSession();
            Transaction tx = session.beginTransaction();
            Query query = session.createQuery("select name from Customer");
            List<Object[]> customers = query.list();
            for(Object c : customers) {
                System.out.println(c);
            }
            tx.commit();
            session.close();    
        }

}

Criteria演示：

package doTest;

import java.util.List;

import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.criterion.Projection;
import org.hibernate.criterion.ProjectionList;
import org.hibernate.criterion.Projections;
import org.hibernate.criterion.Property;
import org.hibernate.criterion.Restrictions;
import org.junit.jupiter.api.Test;
import Util.HibernateUtil;
import caixiaohao.entiy.Customer;


public class CriteriaTest {
    //全表查询
    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction tx = session.beginTransaction();
    
        Criteria ce = session.createCriteria(Customer.class);
        List<Customer> list = ce.list();
        for (Customer customer : list) {
            System.out.println(customer);
        }
        tx.commit();
        session.close();
    }
    //条件查询
        @Test
        public void test2() {
            Session session = HibernateUtil.getSession();
            Transaction tx = session.beginTransaction();
        
            Criteria ce = session.createCriteria(Customer.class);
            ce.add(Restrictions.like("name", "%胖%"));
            List<Customer> list = ce.list();
            for (Customer customer : list) {
                System.out.println(customer);
            }
            tx.commit();
            session.close();
        }
        //分页查询
        @Test
        public void test3() {
            Session session = HibernateUtil.getSession();
            Transaction tx = session.beginTransaction();
        
            Criteria ce = session.createCriteria(Customer.class);
            ce.setFirstResult(2);
            ce.setMaxResults(3);
            List<Customer> list = ce.list();
            for (Customer customer : list) {
                System.out.println(customer);
            }
            tx.commit();
            session.close();
        }
        
        //聚合查询
        @Test
        public void test4() {
            Session session = HibernateUtil.getSession();
            Transaction tx = session.beginTransaction();
        
            Criteria ce = session.createCriteria(Customer.class);
            ce.setProjection(Projections.count("id"));
            Integer count = (Integer)ce.uniqueResult();
            System.out.println(count);
//          List<Customer> list = ce.list();
//          for (Customer customer : list) {
//              System.out.println(customer);
//          }
            tx.commit();
            session.close();
        }
        
        //投影查询
                @Test
                public void test5() {
                    Session session = HibernateUtil.getSession();
                    Transaction tx = session.beginTransaction();
                
                    Criteria ce = session.createCriteria(Customer.class);
                    ProjectionList plist = Projections.projectionList();
                    plist.add(Property.forName("id"));
                    plist.add(Property.forName("name"));
                    ce.setProjection(plist);
                    
                    List<Object[]> list = ce.list();
                    for(Object[] objects : list) {
                        for(Object object : objects ) {
                            System.out.println(object);
                        }
                    }
                    
                    tx.commit();
                    session.close();
                }
}

Sql方式的演示：

package doTest;

import java.util.List;

import org.hibernate.SQLQuery;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.jupiter.api.Test;

import Util.HibernateUtil;

public class SqlTest {

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction tx = session.beginTransaction();

        SQLQuery sqlQuery = session.createSQLQuery("select * from t_order");
        List<Object[]> list = sqlQuery.list();
        for (Object[] objects : list) {
            for (Object object : objects) {
                System.out.print(object + "\t");
            }
            System.out.println();
        }

        tx.commit();
        session.close();
    }
}

PART_THREE
Hibernate整合C3P0：
1.在下好的Hibernate的jar中有C3P0的依赖jar

image.png

2.在hibernat.cfg.xml加入C3P0的配置

<!-- Hibernate整合c3p0 -->
        <property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
        <!-- c3p0详细配置 -->
        <property name="c3p0.min_size">10</property>
        <property name="c3p0.max_size">20</property>

3.测试C3P0

package doTest;

import java.sql.Connection;
import java.sql.SQLException;

import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.jdbc.Work;

import Util.HibernateUtil;
import caixiaohao.entiy.Customer;
import caixiaohao.entiy.Order;

public class test {
    
    public static void main(String[] args) {
Session session = HibernateUtil.getSession();
        
        session.doWork(new Work(){

            @Override
            public void execute(Connection connection) throws SQLException {
                System.out.println(connection);
            }

            
        });
        
        
        session.close();
    }

}

结果

image.png

PART_FOUR
hibernate的配置就到此，它还有相关概念需要自行去深入了解，例如一级缓存，二级缓存，快照，session的瞬时态，持久态，脱管态，lazy加载还有其注释的方式去进行配置等等。