Hibernate实战——组件作为Map的索引

﹏ヽ暗。殇╰゛Y 2021-07-25 00:23 312阅读 0赞

**一 配置文件 **

<?xml version="1.0" encoding="GBK"?>
    
    <!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>
               
               <property  name="connection.driver_class">com.mysql.jdbc.Driver</property>
               
               <property  name="connection.url">jdbc:mysql://localhost/hibernate</property>
               
               <property name="connection.username">root</property>
               
               <property name="connection.password">32147</property>
               
               <property  name="hibernate.c3p0.max_size">20</property>
               
               <property name="hibernate.c3p0.min_size">1</property>
               
               <property  name="hibernate.c3p0.timeout">5000</property>
               
               <property  name="hibernate.c3p0.max_statements">100</property>
               <property  name="hibernate.c3p0.idle_test_period">3000</property>
               <property  name="hibernate.c3p0.acquire_increment">2</property>
               <property  name="hibernate.c3p0.validate">true</property>
               
               <property  name="dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
               
               <property name="hbm2ddl.auto">update</property>
               
               <property name="show_sql">true</property>
               
               <property name="hibernate.format_sql">true</property>
               
               <mapping class="org.crazyit.app.domain.Person"/>
         </session-factory>
    </hibernate-configuration>

**二 PO**

1 Person

package org.crazyit.app.domain;
    
    import java.util.*;
    import javax.persistence.*;
    
    @Entity
    @Table(name="person_inf")
    public class Person
    {
        // 标识属性
        @Id @Column(name="person_id")
        @GeneratedValue(strategy=GenerationType.IDENTITY)
        private Integer id;
        private int age;
        // 集合属性nickPower
        @ElementCollection(targetClass=Integer.class)
        @CollectionTable(name="nick_power_inf", joinColumns
            =@JoinColumn(name="person_id" , nullable=false))
        @Column(name="nick_power" , nullable=false)
        // 指定Map key的类型
        @MapKeyClass(Name.class)
        private Map<Name , Integer> nickPower
            = new HashMap<Name , Integer>();
    
        // id的setter和getter方法
        public void setId(Integer id)
        {
            this.id = id;
        }
        public Integer getId()
        {
            return this.id;
        }
    
        // age的setter和getter方法
        public void setAge(int age)
        {
            this.age = age;
        }
        public int getAge()
        {
            return this.age;
        }
    
        // nickPower的setter和getter方法
        public void setNickPower(Map<Name , Integer> nickPower)
        {
            this.nickPower = nickPower;
        }
        public Map<Name , Integer> getNickPower()
        {
            return this.nickPower;
        }
    }

2 Name

package org.crazyit.app.domain;
    
    import javax.persistence.*;
    import org.hibernate.annotations.Parent;
    
    @Embeddable
    public class Name
    {
        // 定义first成员变量
        @Column(name="person_firstname")
        private String first;
        // 定义last成员变量
        @Column(name="person_lastname")
        private String last;
        // 引用拥有该Name的Person对象
        @Parent
        private Person owner;
    
        // 无参数的构造器
        public Name()
        {
        }
        // 初始化全部成员变量的构造器
        public Name(String first , String last)
        {
            this.first = first;
            this.last = last;
        }
    
        // first的setter和getter方法
        public void setFirst(String first)
        {
            this.first = first;
        }
        public String getFirst()
        {
            return this.first;
        }
    
        // last的setter和getter方法
        public void setLast(String last)
        {
            this.last = last;
        }
        public String getLast()
        {
            return this.last;
        }
    
        // owner的setter和getter方法
        public void setOwner(Person owner)
        {
            this.owner = owner;
        }
        public Person getOwner()
        {
            return this.owner;
        }
        // 重写equals()方法，根据first、last进行判断
        public boolean equals(Object obj)
        {
            if (this == obj)
            {
                return true;
            }
            if (obj != null && obj.getClass() == Name.class)
            {
                Name target = (Name)obj;
                return target.getFirst().equals(getFirst())
                    && target.getLast().equals(getLast());
            }
            return false;
        }
        // 重写hashCode方法，根据first、last计算hashCode值
        public int hashCode()
        {
            return getFirst().hashCode() * 31
                + getLast().hashCode();
        }
    }

**三 测试**

1 工具类

package lee;
    
    import org.hibernate.*;
    import org.hibernate.cfg.*;
    import org.hibernate.service.*;
    import org.hibernate.boot.registry.*;
    
    public class HibernateUtil
    {
        public static final SessionFactory sessionFactory;
    
        static
        {
            try
            {
                // 使用默认的hibernate.cfg.xml配置文件创建Configuration实例
                Configuration cfg = new Configuration()
                    .configure();
                // 以Configuration实例来创建SessionFactory实例
                ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
                    .applySettings(cfg.getProperties()).build();
                sessionFactory = cfg.buildSessionFactory(serviceRegistry);
            }
            catch (Throwable ex)
            {
                System.err.println("Initial SessionFactory creation failed." + ex);
                throw new ExceptionInInitializerError(ex);
            }
        }
    
        // ThreadLocal可以隔离多个线程的数据共享，因此不再需要对线程同步
        public static final ThreadLocal<Session> session
            = new ThreadLocal<Session>();
    
        public static Session currentSession()
            throws HibernateException
        {
            Session s = session.get();
            // 如果该线程还没有Session,则创建一个新的Session
            if (s == null)
            {
                s = sessionFactory.openSession();
                // 将获得的Session变量存储在ThreadLocal变量session里
                session.set(s);
            }
            return s;
        }
    
        public static void closeSession()
            throws HibernateException
        {
            Session s = session.get();
            if (s != null)
                s.close();
            session.set(null);
        }
    }

2 测试类

package lee;
    
    import org.hibernate.Transaction;
    import org.hibernate.Session;
    
    import java.util.*;
    
    import org.crazyit.app.domain.*;
    
    
    public class PersonManager
    {
        public static void main(String[] args)
        {
            PersonManager mgr = new PersonManager();
            mgr.createAndStorePerson();
            HibernateUtil.sessionFactory.close();
        }
        private void createAndStorePerson()
        {
            Session session = HibernateUtil.currentSession();
            Transaction tx = session.beginTransaction();
            // 创建Person对象
            Person person = new Person();
            person.setAge(21);
            // 向Map集合里放入Name对象
            person.getNickPower().put(new Name("Wawa" , "Wawa") , 92);
            person.getNickPower().put(new Name("crazyit.org" , "疯狂Java联盟") , 96);
            session.save(person);
            tx.commit();
            HibernateUtil.closeSession();
        }
    }

**四 测试效果**

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70 1]: /images/20210724/39df3bc6077e4e76a1377ffaf1f7791c.png