Hibernate实战——集合属性的元素为组件

待我称王封你为后i 2021-07-24 20:45 415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
    {
        @Id @Column(name="person_id")
        @GeneratedValue(strategy=GenerationType.IDENTITY)
        private Integer id;
        private int age;
        // Map集合元素是组件
        @ElementCollection(targetClass=Score.class)
        @CollectionTable(name="score_inf",
            joinColumns=@JoinColumn(name="person_id" , nullable=false))
        @MapKeyColumn(name="subject_name")
        @MapKeyClass(String.class)
        private Map<String , Score> scores
            = new HashMap<>();
        // List集合元素是组件
        @ElementCollection(targetClass=Name.class)
        @CollectionTable(name="nick_inf",
            joinColumns=@JoinColumn(name="person_id" , nullable=false))
        @OrderColumn(name="list_order")
        private List<Name> nicks
            = new ArrayList<>();
    
        // 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;
        }
    
        // nicks的setter和getter方法
        public void setNicks(List<Name> nicks)
        {
            this.nicks = nicks;
        }
        public List<Name> getNicks()
        {
            return this.nicks;
        }
    
        // scores的setter和getter方法
        public void setScores(Map<String , Score> scores)
        {
            this.scores = scores;
        }
        public Map<String , Score> getScores()
        {
            return this.scores;
        }
    }

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;
        }
    
    }

3 Score

package org.crazyit.app.domain;
    
    import javax.persistence.*;
    import org.hibernate.annotations.Parent;
    
    @Embeddable
    public class Score
    {
        // 定义first成员变量
        @Column(name="score_level")
        private String level;
        // 定义last成员变量
        @Column(name="score_mark")
        private Integer mark;
        // 引用拥有该Name的Person对象
        @Parent
        private Person owner;
    
        // 无参数的构造器
        public Score()
        {
        }
        // 初始化全部成员变量的构造器
        public Score(String level , Integer mark)
        {
            this.level = level;
            this.mark = mark;
        }
    
        // level的setter和getter方法
        public void setLevel(String level)
        {
            this.level = level;
        }
        public String getLevel()
        {
            return this.level;
        }
    
        // mark的setter和getter方法
        public void setMark(Integer mark)
        {
            this.mark = mark;
        }
        public Integer getMark()
        {
            return this.mark;
        }
    
        // owner的setter和getter方法
        public void setOwner(Person owner)
        {
            this.owner = owner;
        }
        public Person getOwner()
        {
            return this.owner;
        }
    
    }

**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();
            //为Person对象设置属性
            person.setAge(29);
            //创建一个Map集合
            Map<String , Name> nicks =
                new HashMap<String , Name>();
            // 向List集合里放入Name对象
            person.getNicks().add(new Name("Wawa" , "Wawa"));
            person.getNicks().add(new Name("Yeeku" , "Lee"));
            // 向List集合里放入Score对象
            person.getScores().put("语文" , new Score("良好" , 85));
            person.getScores().put("数学" , new Score("优秀" , 92));
            session.save(person);
            tx.commit();
            HibernateUtil.closeSession();
        }
    }

**四 测试结果**

Hibernate:
        insert
        into
            person_inf
            (age)
        values
            (?)
    Hibernate:
        insert
        into
            nick_inf
            (person_id, list_order, person_firstname,  person_lastname)
        values
            (?, ?, ?, ?)
    Hibernate:
        insert
        into
            nick_inf
            (person_id, list_order, person_firstname,  person_lastname)
        values
            (?, ?, ?, ?)
    Hibernate:
        insert
        into
            score_inf
            (person_id, subject_name, score_level, score_mark)
        values
            (?, ?, ?, ?)
    Hibernate:
        insert
        into
            score_inf
            (person_id, subject_name, score_level, score_mark)
        values
            (?, ?, ?, ?)

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