学步园

Map 的第一种结构 Map<Integer,String>

Team.java

package com.wansha.pojo;
/**
 *   一个班级team 由多个学生Map组成，map分为键（学号），值（学生姓名）
 */
import java.util.HashMap;
import java.util.Map;

public class Team {
	private int id;
	private String teamName;
	private Map<Integer,String> student = new HashMap<Integer,String>();
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getTeamName() {
		return teamName;
	}
	public void setTeamName(String teamName) {
		this.teamName = teamName;
	}
	public Map<Integer, String> getStudent() {
		return student;
	}
	public void setStudent(Map<Integer, String> student) {
		this.student = student;
	}
}

Team.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
 "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
  "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
<hibernate-mapping>
	<class name="com.wansha.pojo.Team" table="team">
		<id name="id" column="id" type="int">
			<generator class="identity"></generator>
		</id>
		<property name="teamName" column="teamName" type="string" />
		<map name="student" table="student">
			<key column="team_id" />
			<index column="student_num" type="int"/>
			<element column="student_name" type="string"></element>
		</map>
	</class>
</hibernate-mapping>  

Test.java

package com.wansha.util;

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

import com.wansha.pojo.Team;

public class Test {
	public static void main(String[] args) {
/*		Team team = new Team();
		team.setTeamName("team 1");
		team.getStudent().put(12, "sharp");
		team.getStudent().put(13, "hailie");
		team.getStudent().put(15, "dudu");
		Session session = HibernateUtil.getSession();
		Transaction ts = null;
		try{
			ts = session.beginTransaction();
			session.save(team);
			ts.commit();
		}catch(Exception ex){
			if(ts != null){
				ts.rollback();
			}
		}finally{
			HibernateUtil.close(session);
		}*/
		
		Session session = HibernateUtil.getSession();
		Transaction ts = null;
		try{
			ts = session.beginTransaction();
			Team team = (Team)session.get(Team.class,1);
			team.getStudent().remove(12);
			ts.commit();
		}catch(Exception ex){
			if(ts != null){
				ts.rollback();
			}
		}finally{
			HibernateUtil.close(session);
		}
	}
}

Map 的第二种结构 Map<Integer,Object>

Team.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
 "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
  "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
<hibernate-mapping>
	<class name="com.wansha.pojo.Team" table="team">
		<id name="id" column="id" type="int">
			<generator class="identity"></generator>
		</id>
		<property name="teamName" column="teamName" type="string" />
		<map name="student" table="student" cascade="all" inverse="true" > // lazy="false" 不加也可以通过entryset = map.entrySet();读取student
			<key column="team_id" />
			<index column="cardid" type="int"/>
			<one-to-many class="com.wansha.pojo.Student"/>
		</map>
	</class>
</hibernate-mapping>  

Student.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
 "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
  "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
<hibernate-mapping>
	<class name="com.wansha.pojo.Student" table="student">
		<id name="id" column="id" type="int">
			<generator class="identity"></generator>
		</id>
		<property name="name" column="name" type="string" />
		<property name="cardid" column="cardid" type="int" />
		<many-to-one name="team" class="com.wansha.pojo.Team" column="team_id"/>
	</class>
</hibernate-mapping>  

Test.java

package com.wansha.util;

import java.util.Map;
import java.util.Set;
import java.util.Map.Entry;

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

import com.wansha.pojo.Student;
import com.wansha.pojo.Team;

public class Test {
	public static void main(String[] args) {
/*		Team team = new Team();
		team.setTeamName("team 1");
		
		Student student1 = new Student();
		student1.setCardid(111);
		student1.setName("sharp");
		student1.setTeam(team);
		
		Student student2 = new Student();
		student2.setCardid(222);
		student2.setName("hailie");
		student2.setTeam(team);
		
		Student student3 = new Student();
		student3.setCardid(333);
		student3.setName("dudu");
		student3.setTeam(team);
		
		team.getStudent().put(student1.getCardid(), student1);
		team.getStudent().put(student2.getCardid(), student2);
		team.getStudent().put(student3.getCardid(), student3);
		
		Session session = HibernateUtil.getSession();
		Transaction ts = null;
		try{
			ts = session.beginTransaction();
			session.save(team);
			ts.commit();
		}catch(Exception ex){
			if(ts != null){
				ts.rollback();
			}
		}finally{
			HibernateUtil.close(session);
		}*/
		
		//--------------------------------------------------------------------------------
		
		Session session = HibernateUtil.getSession();
		Transaction ts = null;
		Set<Entry<Integer, Student>> entryset = null;
		try{
			ts = session.beginTransaction();
			Team team = (Team)session.get(Team.class,2);
			Map<Integer, Student> map = team.getStudent();
			entryset = map.entrySet();
			ts.commit();
		}catch(Exception ex){
			if(ts != null){
				ts.rollback();
			}
		}finally{
			HibernateUtil.close(session);
		}
		for(Entry<Integer, Student> entry: entryset){
			System.out.println(((Student)entry.getValue()).getName());
		}
	}
}