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.