吴裕雄--天生自然轻量级JAVA EE企业应用开发Struts2Sping4Hibernate整合开发学习笔记：Hibernate_implicit_join

<?xml version="1.0" encoding="GBK"?>
<project name="hibernate" basedir="." default="">
    <property name="src" value="src"/>
    <property name="dest" value="classes"/>

    <path id="classpath">
        <fileset dir="../../lib">
            <include name="**/*.jar"/>
        </fileset>
        <pathelement path="${dest}"/>
    </path>

    <target name="compile" description="Compile all source code">
        <delete dir="${dest}"/>
        <mkdir dir="${dest}"/>
        <copy todir="${dest}">
            <fileset dir="${src}">
                <exclude name="**/*.java"/>
            </fileset>        
        </copy>
        <javac destdir="${dest}" debug="true" includeantruntime="yes"
            deprecation="false" optimize="false" failonerror="true">
            <src path="${src}"/>
            <classpath refid="classpath"/>
            <compilerarg value="-Xlint:deprecation"/>
        </javac>
    </target>

    <target name="run" description="Run the main class" depends="compile">
        <java classname="lee.HqlQuery" fork="yes" failonerror="true">
            <classpath refid="classpath"/>
        </java>
    </target>

</project>

drop database if exists hibernate;

create database hibernate;

use hibernate;

CREATE TABLE event_inf (
  event_id int(11) NOT NULL auto_increment,
  happenDate date default NULL,
  title varchar(255) default NULL,
  PRIMARY KEY  (event_id)
);

INSERT INTO event_inf VALUES
(1,'2004-10-03','很高兴的事情'),
(2,'2005-10-03','很普通的事情'),
(3,'2004-10-04','疯狂Java筹备中'),
(4,'2005-10-05','疯狂Java开始培训');

CREATE TABLE person_inf (
  person_id int(11) NOT NULL auto_increment,
  name varchar(255) default NULL,
  age int(11) default NULL,
  event_id int(11),
  PRIMARY KEY (person_id),
  FOREIGN KEY (event_id) REFERENCES event_inf(event_id)
);


INSERT INTO person_inf VALUES
(1,'crazyit.org',30 , 1),
(2,'老朱',30 , 1);


CREATE TABLE person_email (
  person_id int(11) NOT NULL,
  email varchar(255) default NULL,
  KEY FKECD3B632CC53FFDC (person_id),
  FOREIGN KEY (person_id) REFERENCES person_inf (person_id)
);

INSERT INTO person_email VALUES 
(1,'crazyit@crazyit.org'),
(1,'crazyit@fkit.com'),
(2,'dddd@163.com'),
(2,'vvvvvv@163.com');

<?xml version="1.0" encoding="GBK"?>
<!-- 指定Hibernate配置文件的DTD信息 -->
<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<!-- hibernate-configuration是配置文件的根元素 -->
<hibernate-configuration>
    <session-factory>
        <!-- 指定连接数据库所用的驱动 -->
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <!-- 指定连接数据库的url，其中hibernate是本应用连接的数据库名 -->
        <property name="connection.url">jdbc:mysql://localhost/hibernate</property>
        <!-- 指定连接数据库的用户名 -->
        <property name="connection.username">root</property>
        <!-- 指定连接数据库的密码 -->
        <property name="connection.password">32147</property>
        <!-- 指定连接池里最大连接数 -->
        <property name="hibernate.c3p0.max_size">20</property>
        <!-- 指定连接池里最小连接数 -->
        <property name="hibernate.c3p0.min_size">1</property>
        <!-- 指定连接池里连接的超时时长 -->
        <property name="hibernate.c3p0.timeout">5000</property>
        <!-- 指定连接池里最大缓存多少个Statement对象 -->
        <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>
        <!-- 指定数据库方言 -->
        <property name="dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
        <!-- 根据需要自动创建数据库 -->
        <property name="hbm2ddl.auto">update</property>
        <!-- 显示Hibernate持久化操作所生成的SQL -->
        <property name="show_sql">true</property>
        <!-- 将SQL脚本进行格式化后再输出 -->
        <property name="hibernate.format_sql">true</property>
        <!-- 罗列所有持久化类的类名 -->
        <mapping class="org.crazyit.app.domain.Person"/>
        <mapping class="org.crazyit.app.domain.MyEvent"/>
    </session-factory>
</hibernate-configuration>

package org.crazyit.app.domain;

import java.util.*;

import javax.persistence.*;
/**
 * Description:
 * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
 * <br/>Copyright (C), 2001-2016, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee kongyeeku@163.com
 * @version  1.0
 */
@Entity
@Table(name="event_inf")
public class MyEvent
{
    // 定义标识属性
    @Id @Column(name="event_id")
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer id;
    // 定义事件名称的成员变量
    private String title;
    // 定义事件发生时间的成员变量
    private Date happenDate;
    // 定义该MyEvent实体关联的所有Person实体
    @ManyToMany(targetEntity=Person.class , mappedBy="myEvent")
    private Set<Person> actors
        = new HashSet<>();

    // id的setter和getter方法
    public void setId(Integer id)
    {
        this.id = id;
    }
    public Integer getId()
    {
        return this.id;
    }

    // title的setter和getter方法
    public void setTitle(String title)
    {
        this.title = title;
    }
    public String getTitle()
    {
        return this.title;
    }

    // happenDate的setter和getter方法
    public void setHappenDate(Date happenDate)
    {
        this.happenDate = happenDate;
    }
    public Date getHappenDate()
    {
        return this.happenDate;
    }

    // actors的setter和getter方法
    public void setActors(Set<Person> actors)
    {
        this.actors = actors;
    }
    public Set<Person> getActors()
    {
        return this.actors;
    }
}

package org.crazyit.app.domain;

import java.util.*;

import javax.persistence.*;
/**
 * Description:
 * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
 * <br/>Copyright (C), 2001-2016, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee kongyeeku@163.com
 * @version  1.0
 */
@Entity
@Table(name = "person_inf")
public class Person
{
    // 定义标识属性
    @Id @Column(name = "person_id")
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer id;
    // 定义Person实例的name成员变量
    private String name;
    // 定义Person实例的age成员变量
    private int age;
    // 定义该Person实体关联的MyEvent实体
    @ManyToOne(targetEntity=MyEvent.class)
    @JoinColumn(name = "event_id" , referencedColumnName="event_id")
    private MyEvent myEvent;
    // 定义一个集合属性
    // 集合属性，保留该对象关联的学校
    @ElementCollection(targetClass=String.class)
    @CollectionTable(name="person_email_inf",
        joinColumns=@JoinColumn(name="person_id" , nullable=false))
    @Column(name="email_detail" , nullable=false)
    private Set<String> emails
        = new HashSet<>();

    // id的setter和getter方法
    public void setId(Integer id)
    {
        this.id = id;
    }
    public Integer getId()
    {
        return this.id;
    }

    // name的setter和getter方法
    public void setName(String name)
    {
        this.name = name;
    }
    public String getName()
    {
        return this.name;
    }

    // age的setter和getter方法
    public void setAge(int age)
    {
        this.age = age;
    }
    public int getAge()
    {
        return this.age;
    }

    // myEvent的setter和getter方法
    public void setMyEvent(MyEvent myEvent)
    {
        this.myEvent = myEvent;
    }
    public MyEvent getMyEvent()
    {
        return this.myEvent;
    }

    // emails的setter和getter方法
    public void setEmails(Set<String> emails)
    {
        this.emails = emails;
    }
    public Set<String> getEmails()
    {
        return this.emails;
    }

}

package lee;

import org.hibernate.*;
import org.hibernate.cfg.*;
import org.hibernate.service.*;
import org.hibernate.boot.registry.*;
/**
 * Description:
 * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
 * <br/>Copyright (C), 2001-2016, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee kongyeeku@163.com
 * @version  1.0
 */
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);
    }
}

package lee;

import org.hibernate.Transaction;
import org.hibernate.Session;

import java.text.DateFormat;
import java.text.SimpleDateFormat;

import java.util.*;

import org.crazyit.app.domain.*;
/**
 * Description:
 * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
 * <br/>Copyright (C), 2001-2016, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee kongyeeku@163.com
 * @version  1.0
 */
public class HqlQuery
{
    public static void main(String[] args)
        throws Exception
    {
        HqlQuery mgr = new HqlQuery();
        // 调用查询方法
        mgr.findPersons();
        // 调用第二个查询方法
        mgr.findPersonsByHappenDate();
        mgr.findPersonsFetchMyEvent();
    }

    //c第一个查询方法
    private void findPersons()
    {
        // 获得Hibernate Session
        Session sess = HibernateUtil.currentSession();
        // 开始事务
        Transaction tx = sess.beginTransaction();
        // 以HQL语句创建Query对象,HQL语句使用隐式连接
        List pl = sess.createQuery("from Person p where p.myEvent.title > :title")
            // 执行setString()方法为HQL语句的参数赋值
            .setString("title", " ")
            //Query调用list()方法访问查询的全部实例
            .list();
        // 遍历查询的全部结果
        for (Object ele : pl)
        {
            Person p = (Person)ele;
            System.out.println(p.getName());
        }
        // 提交事务
        tx.commit();
        HibernateUtil.closeSession();
    }
    // 第二个查询方法
    private void findPersonsByHappenDate()throws Exception
    {
        // 获得Hibernate Session对象
        Session sess = HibernateUtil.currentSession();
        Transaction tx = sess.beginTransaction();
        System.out.println("====开始通过日期查找人====");
        // 以HQL语句创建Query对象,HQL语句使用显式连接
        // 因为没有使用fetch关键字，所以返回List集合元素是被查询实体
        List pl = sess.createQuery("select p from Person p left join "
            + "p.myEvent event where event.happenDate < :endDate")
            .setDate("endDate",new Date())
            .list();
        // 遍历结果集
        for (Object ele : pl)
        {
            Person p = (Person)ele;
            System.out.println(p.getName());
            // 因为执行HQL时没有使用fetch，
            // 所以只能在Session没有关闭时访问Person关联实体的属性
            System.out.println(p.getMyEvent().getTitle());
        }
        tx.commit();
        HibernateUtil.closeSession();
    }

    // 第三个查询方法，测试fetch关键字
    private void findPersonsFetchMyEvent()throws Exception
    {
        // 获得Hibernate Session对象
        Session sess = HibernateUtil.currentSession();
        Transaction tx = sess.beginTransaction();
        System.out.println("====测试fetch查询====");
        // 以HQL语句创建Query对象,HQL语句使用显式连接
        // 因为使用了fetch关键字，所以返回结果中已有包含关联实体
        List pl = sess.createQuery("from Person p left join fetch "
            + "p.myEvent event where event.happenDate < :endDate")
            .setDate("endDate",new Date())
            .list();
        tx.commit();
        HibernateUtil.closeSession();
        // 遍历结果集
        for (Object ele : pl)
        {
            Person p = (Person)ele;
            System.out.println(p.getName());
            // 因为HQL语句中使用了fecth关键字
            // 所以可以在Session关闭后访问Person关联实体的属性
            System.out.println(p.getMyEvent().getTitle());
        }
    }
}