HIbernate Y映射 Map、list、set

1.总

• set:不允许重复、无序
• list:有序、重复
• map:key-value对形式

2.map与set标签中的element子标签映射的是原子类型（string、data、int、long...），即就是能够直接映射到数据库表字段上的类型，而one-to-many映射的则是实体类型，指的是无法映射到表的某个字段，而是要映射到整张表的类型。

3.map

（1）原子类型

public class Team
{
    private String id;
    private String name;
    private Map students = new HashMap();
}

<hibernate-mapping>
    <class name="com.liule.hibernate.Team" table="team">
        <id name="id" column="id" type="string">
            <generator class="uuid"></generator>
        </id>
        
        <property name="name"  type="string">
            <column name="name" length="50"></column>
        </property>
    
        <map name="students" table="team_student"> <!-- table：存放map内的key-value对的值 -->
            <key column="team_id"></key> <!-- 在team_student表内靠team_id联系到team表 -->
            <index column="name" type="string"></index> <!-- 在map内key的值 -->
            <element column="description" type="string" ></element> <!-- map内value的值 -->
        
        </map>
    </class>
</hibernate-mapping>

public static void main(String[] args)
    {
        //生成表
        SchemaExport export = new SchemaExport(new Configuration().configure());
        export.create(true,true);
    }

Team team = new Team();
        
        team.setName("team");
    
        
        Map map = team.getStudents();
        map.put("zhangsan","sdas");
        map.put("lisi","sadasd");
        
        Session session = sf.openSession();
        Transaction ts = null;
        try
        {
            ts = session.beginTransaction();
            session.save(team);
            ts.commit();
        }
        catch(Exception ex)
        {
            if(null != ts)
            {
                ts.rollback();
            }
        }
        finally
        {
            session.close();
        }

（2）实体类型

public class Team
{
    private String id;
    private String name;
    private Map students = new HashMap();
}

public class Student
{
    private String id;
    private String name;
    private String cardId;
    private int age;
    private Team team;
}

<hibernate-mapping>
    <class name="com.liule.hibernate.Team" table="team">
    
        <id name="id" column="id" type="string">
            <generator class="uuid"></generator>
        </id>
        
        <property name="name"  type="string">
            <column name="name" length="50"></column>
        </property>
    
        <map name="students" table="team_student" cascade="all"> <!-- table：存放map内的key-value对的值 -->
            <key column="team_id"></key> <!-- 在team_student表内靠team_id联系到team表 -->
            <index column="card_id" type="string"></index> <!-- 在map内key的值 -->
            <one-to-many class="com.liule.hibernate.Student"/><!-- map内value的值 -->
        
        </map>
    </class>
</hibernate-mapping>

<hibernate-mapping>
    <class name="com.liule.hibernate.Student" table="Student">
        <id name="id" column="id" type="string">
            <generator class="uuid"></generator>
        </id>
        
        <property name="name"  type="string">
            <column name="name" length="50"></column>
        </property>
        <property name="cardId" column="card_id" type="string"></property><!-- key -->
        <property name="age" column="age" type="int"></property>
        
        <many-to-one name="team" column="team_id" class="com.liule.hibernate.Team"></many-to-one>
    </class>
</hibernate-mapping>

public static void main(String[] args)
    {
        Team team = new Team();
        team.setName("team1");
    
        Student student = new Student();
        student.setAge(12);
        student.setName("liule");
    
        student.setTeam(team);
        
        team.getStudents().put("123456",student);
        
        Session session = sf.openSession();
        Transaction ts = null;
        try
        {
            session.save(team);
            ts = session.beginTransaction();
            ts.commit();
        }
        catch(Exception ex)
        {
            ex.printStackTrace();
            if(null != ts)
            {
                ts.rollback();
            }
        }
        finally
        {
            session.close();
        }
    }

4.set

public class Team
{
    private String id;
    private String name;
    private Set students = new HashSet();
}

<hibernate-mapping>
    <class name="com.liule.hibernate.Team" table="team">
    
        <id name="id" column="id" type="string">
            <generator class="uuid"></generator>
        </id>
        
        <property name="name"  type="string">
            <column name="name" length="50"></column>
        </property>
    
        <set name="students" table="student" cascade="all"> <!-- 将set内容，设置在team_table表 -->
            <key column="team_id"></key> 
            <element column="name" type="string"></element><!-- column映射到name这一列 -->
        
        </set>
    </class>
</hibernate-mapping>

public static void main(String[] args)
    {
        Team team = new Team();
        team.setName("team1");
        
        team.getStudents().add("zhangsan");
        
        
        Session session = sf.openSession();
        Transaction ts = null;
        try
        {
            session.save(team);
            ts = session.beginTransaction();
            ts.commit();
        }
        catch(Exception ex)
        {
            ex.printStackTrace();
            if(null != ts)
            {
                ts.rollback();
            }
        }
        finally
        {
            session.close();
        }
    }

5.list

public class Team
{
    private String id;
    private String name;
    private List students = new ArrayList();
}

public class Student
{
    private String id;
    private String name;
    private String cardId;
    private int age;
    private Team team;

<hibernate-mapping>
    <class name="com.liule.hibernate.Team" table="team">
    
        <id name="id" column="id" type="string">
            <generator class="uuid"></generator>
        </id>
        
        <property name="name"  type="string">
            <column name="name" length="50"></column>
        </property>
    
        <list name="students" table="student" cascade="all">
            <key column="team_id"></key>
            <index column="index_"></index><!-- 所存放的是索引的位置 -->
            <one-to-many class="com.liule.hibernate.Student"/>
        </list>
    </class>
</hibernate-mapping>

<hibernate-mapping>
    <class name="com.liule.hibernate.Student" table="Student">
        <id name="id" column="id" type="string">
            <generator class="uuid"></generator>
        </id>
        
        <property name="name"  type="string">
            <column name="name" length="50"></column>
        </property>
        <property name="cardId" column="card_id" type="string"></property><!-- key -->
        <property name="age" column="age" type="int"></property>
        
        <many-to-one name="team" column="team_id" class="com.liule.hibernate.Team"></many-to-one>
    </class>
</hibernate-mapping>

public static void main(String[] args)
    {
        Team team = new Team();
        team.setName("team1");
        
        Student student1 = new Student();
        Student student2 = new Student();
        Student student3 = new Student();
        
        student1.setAge(10);
        student1.setCardId("asd");
        student1.setName("zhangsan");
        student1.setTeam(team);
        
        student2.setAge(11);
        student2.setCardId("asdsa");
        student2.setName("lisi");
        student2.setTeam(team);
        
        student3.setAge(12);
        student3.setCardId("asasad");
        student3.setName("wangwu");
        student3.setTeam(team);
        
        team.getStudents().add(student1);
        team.getStudents().add(student2);
        team.getStudents().add(student3);
        
    
        
        Session session = sf.openSession();
        session.save(team);
        Transaction ts = null;
        try
        {
            session.save(team);
            ts = session.beginTransaction();
            ts.commit();
        }
        catch(Exception ex)
        {
            ex.printStackTrace();
            if(null != ts)
            {
                ts.rollback();
            }
        }
        finally
        {
            session.close();
        }
    }