Hibernate逍遥游记-第7章 Hibernate的检索策略和检索方式(<set lazy="false" fetch="join">、left join fetch、FetchMode.JOIN、)

1.

 <?xml version="1.0"?>
 <!DOCTYPE hibernate-mapping
 PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 <hibernate-mapping >

    <class name="mypack.Monkey" table="MONKEYS">

       <id name="id" type="long" column="ID">
         <generator class="increment"/>
       </id>

       <property name="name" type="string" column="NAME" />

       <many-to-one
         name="team"
         column="TEAM_ID"
         class="mypack.Team"
         lazy="proxy"
        />

     </class>

 </hibernate-mapping>

2.

 package mypack;

 public class Monkey{

     private Long id;
     private String name;
     private Team team;

     public Monkey(String name, Team team) {
         this.name = name;
         this.team = team;
     }

     public Monkey() {
     }

     public Long getId() {
         return this.id;
     }

     public void setId(Long id) {
         this.id = id;
     }

     public String getName() {
         return this.name;
     }

     public void setName(String name) {
         this.name = name;
     }

     public Team getTeam() {
         return this.team;
     }

     public void setTeam(Team team) {
         this.team = team;
     }
 }

3.

 <?xml version="1.0"?>
 <!DOCTYPE hibernate-mapping
 PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 <hibernate-mapping >

   <class name="mypack.Team" table="TEAMS" >
     <id name="id" type="long" column="ID">
       <generator class="increment"/>
     </id>

     <property name="name" type="string" column="NAME"  />

    <set
         name="monkeys"
         inverse="true"
         lazy="true">

         <key column="TEAM_ID" />
         <one-to-many class="mypack.Monkey" />
      </set>   

   </class>
 </hibernate-mapping>

4.

 package mypack;

 import java.util.Set;
 import java.util.HashSet;

 public class Team {

     private Long id;
     private String name;
     private Set monkeys=new HashSet();

     public Team(String name, Set monkeys) {
         this.name = name;
         this.monkeys = monkeys;
     }

     public Team() {
     }

     public Team(Set monkeys) {
         this.monkeys = monkeys;
     }

     public Long getId() {
         return this.id;
     }

     public void setId(Long id) {
         this.id = id;
     }

     public String getName() {
         return this.name;
     }

     public void setName(String name) {
         this.name = name;
     }

     public Set getMonkeys() {
         return this.monkeys;
     }

     public void setMonkeys(Set monkeys) {
         this.monkeys = monkeys;
     }

 }

5.

 package mypack;

 import org.hibernate.*;
 import org.hibernate.cfg.Configuration;
 import java.util.*;

 public class BusinessService{
   public static SessionFactory sessionFactory;
   static{
      try{
       // Create a configuration based on the properties file we've put
        Configuration config = new Configuration();
       //load hibernate.cfg.xml
        config.configure();
       // Get the session factory we can use for persistence
       sessionFactory = config.buildSessionFactory();
     }catch(RuntimeException e){e.printStackTrace();throw e;}
   }

   public void findAllTeams(){
     Session session = sessionFactory.openSession();
     Transaction tx = null;
     try {
       tx = session.beginTransaction();

       System.out.println("findAllTeams():executing session.createQuery().list()");
       List teamLists=session.createQuery("from Team as m").list();

       System.out.println("findAllTeams():executing teamLists.iterator()");
       Iterator teamIterator=teamLists.iterator();

       System.out.println("findAllTeams():iterating team1");
       Team team1=(Team)teamIterator.next();

       System.out.println("findAllTeams():iterating team2");
       Team team2=(Team)teamIterator.next();

       System.out.println("findAllTeams():iterating team3");
       Team team3=(Team)teamIterator.next();

       System.out.println("findAllTeams():iterating team4");
       Team team4=(Team)teamIterator.next();

       System.out.println("findAllTeams():executing team1.getMonkeys().iterator()");
       Iterator monkeyIterator1=team1.getMonkeys().iterator();

       System.out.println("findAllTeams():executing team2.getMonkeys().iterator()");
       Iterator monkeyIterator2=team2.getMonkeys().iterator();

       System.out.println("findAllTeams():executing team3.getMonkeys().iterator()");
       Iterator monkeyIterator3=team3.getMonkeys().iterator();

       System.out.println("findAllTeams():executing team4.getMonkeys().iterator()");
       Iterator monkeyIterator4=team4.getMonkeys().iterator();

       tx.commit();

     }catch (RuntimeException e) {
       if (tx != null) {
          tx.rollback();
       }
       throw e;
     } finally {
        session.close();
     }
   }

   public void loadTeam(){

     Session session = sessionFactory.openSession();
     Transaction tx = null;
     Team team=null;
     try {
       tx = session.beginTransaction();

       System.out.println("loadTeam():executing session.load()");
       team=(Team)session.load(Team.class,new Long(1));

       System.out.println("loadTeam():executing team.getName()");
       team.getName();

       System.out.println("loadTeam():executing team.getMonkeys().iterator()");
       Iterator monkeyIterator=team.getMonkeys().iterator();

       tx.commit();

     }catch (RuntimeException e) {
       if (tx != null) {
         tx.rollback();
       }
       throw e;
     } finally {
       session.close();
     }
   }

   public void getTeam(){
     Session session = sessionFactory.openSession();
     Transaction tx = null;
     try {
       tx = session.beginTransaction();
       System.out.println("getTeam():executing session.get()");
       Team team=(Team)session.get(Team.class,new Long(1));

       System.out.println("getTeam():executing team.getName()");
       team.getName();

       System.out.println("getTeam():executing team.getMonkeys().iterator()");
       Iterator monkeyIterator=team.getMonkeys().iterator();

       tx.commit();

     }catch (RuntimeException e) {
       if (tx != null) {
         tx.rollback();
       }
       throw e;
     } finally {
       session.close();
     }
   }

   public void getMonkey(){
     Session session = sessionFactory.openSession();
     Transaction tx = null;
     try {
       tx = session.beginTransaction();
       System.out.println("getMonkey():executing session.get()");
       Monkey monkey=(Monkey)session.get(Monkey.class,new Long(1));

       System.out.println("getMonkey():executing monkey.getName()");
       monkey.getName();

       System.out.println("getMonkey():executing monkey.getTeam()");
       Team team=monkey.getTeam();

       System.out.println("getMonkey():executing team.getName()");
       team.getName();

       tx.commit();

     }catch (RuntimeException e) {
       if (tx != null) {
         tx.rollback();
       }
       throw e;
     } finally {
       session.close();
     }
   }

   public void loadMonkey(){
     Session session = sessionFactory.openSession();
     Transaction tx = null;
     try {
       tx = session.beginTransaction();
       System.out.println("loadMonkey():executing session.load()");
       Monkey monkey=(Monkey)session.load(Monkey.class,new Long(1));

       System.out.println("loadMonkey():executing monkey.getName()");
       monkey.getName();

       System.out.println("loadMonkey():executing monkey.getTeam()");
       Team team=monkey.getTeam();

       System.out.println("loadMonkey():executing team.getName()");
       team.getName();

       tx.commit();

     }catch (RuntimeException e) {
       if (tx != null) {
         tx.rollback();
       }
       throw e;
     } finally {
       session.close();
     }
   }

   public void findAllMonkeys(){
     Session session = sessionFactory.openSession();
     Transaction tx = null;
     try {
       tx = session.beginTransaction();

       System.out.println("findAllMonkeys():executing session.createQuery().list()");
       List monkeyLists=session.createQuery("from Monkey as m ").list();

       System.out.println("findAllMonkeys():executing monkeyLists.iterator()");
       Iterator monkeyIterator=monkeyLists.iterator();

       System.out.println("findAllMonkeys():iterating monkey1");
       Monkey monkey1=(Monkey)monkeyIterator.next();

       System.out.println("findAllMonkeys():iterating monkey2");
       Monkey monkey2=(Monkey)monkeyIterator.next();

       System.out.println("findAllMonkeys():iterating monkey3");
       Monkey monkey3=(Monkey)monkeyIterator.next();

       System.out.println("findAllMonkeys():iterating monkey4");
       Monkey monkey4=(Monkey)monkeyIterator.next();

       System.out.println("findAllMonkeys():iterating monkey5");
       Monkey monkey5=(Monkey)monkeyIterator.next();

       System.out.println("findAllMonkeys():iterating monkey6");
       Monkey monkey6=(Monkey)monkeyIterator.next();

       System.out.println("findAllMonkeys():executing monkey1.getTeam()");
       Team team1=monkey1.getTeam();

       System.out.println("findAllMonkeys():executing team1.getName()");
       if(team1!=null) team1.getName();

       System.out.println("findAllMonkeys():executing monkey2.getTeam()");
       Team team2=monkey2.getTeam();

       System.out.println("findAllMonkeys():executing team2.getName()");
       if(team2!=null)team2.getName();

       System.out.println("findAllMonkeys():executing monkey3.getTeam()");
       Team team3=monkey3.getTeam();

       System.out.println("findAllMonkeys():executing team3.getName()");
       if(team3!=null)team3.getName();

       System.out.println("findAllMonkeys():executing monkey4.getTeam()");
       Team team4=monkey4.getTeam();

       System.out.println("findAllMonkeys():executing team4.getName()");
       if(team4!=null)team4.getName();

       System.out.println("findAllMonkeys():executing monkey5.getTeam()");
       Team team5=monkey5.getTeam();

       System.out.println("findAllMonkeys():executing team5.getName()");
       if(team5!=null)team5.getName();

       System.out.println("findAllMonkeys():executing monkey6.getTeam()");
       Team team6=monkey6.getTeam();

       System.out.println("findAllMonkeys():executing team6.getName()");
       if(team6!=null)team6.getName();

       tx.commit();

     }catch (RuntimeException e) {
       if (tx != null) {
         tx.rollback();
       }
       throw e;
     } finally {
       session.close();
     }
   }

   public void findTeamLeftJoinMonkey(){
     Session session = sessionFactory.openSession();
     Transaction tx = null;
     try {
       tx = session.beginTransaction();
       System.out.println("findTeamLeftJoinMonkey():executing session.createQuery().list()");
       List teamLists=session
        .createQuery("from Team as t left join fetch t.monkeys where t.id=1")
        .list();

       System.out.println("findTeamLeftJoinMonkey():executing teamLists.iterator()");
       Iterator teamIterator=teamLists.iterator();

       System.out.println("findTeamLeftJoinMonkey():iterating team");
       Team team=(Team)teamIterator.next();

       System.out.println("findTeamLeftJoinMonkey():executing team.getMonkeys().iterator()");
       Iterator monkeyIterator=team.getMonkeys().iterator();

       tx.commit();

     }catch (RuntimeException e) {
       if (tx != null) {
         tx.rollback();
       }
       throw e;
     } finally {
       session.close();
     }
   }

     public void test(){
       loadTeam();
       getTeam();
       findAllTeams();

       loadMonkey();
       getMonkey();
       findAllMonkeys();
       findTeamLeftJoinMonkey();
   }

   public static void main(String args[]) throws Exception {
     //new BusinessService().test();
     new BusinessService().loadTeam();
     sessionFactory.close();
   }
 }

6.

 <?xml version="1.0" encoding="utf-8" ?>
 <!DOCTYPE hibernate-configuration
  PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN"
  "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

 <hibernate-configuration>
     <session-factory>
         <property name="dialect">
             org.hibernate.dialect.MySQLDialect
         </property>
         <property name="connection.driver_class">
             com.mysql.jdbc.Driver
         </property>
         <property name="connection.url">
             jdbc:mysql://localhost:3306/sampledb
         </property>
         <property name="connection.username">
             root
         </property>
         <property name="connection.password">
             1234
         </property>

         <property name="show_sql">true</property>

         <mapping resource="mypack/Team.hbm.xml" />
         <mapping resource="mypack/Monkey.hbm.xml" />
     </session-factory>
 </hibernate-configuration>

7.