映射关系级别注解

映射关系级别注解

一对一单向外键

@OneToOne(cascade=CascadeType.ALL)

@JoinColumn(name="pid",unique=true)

注意：保存时应该先保存外键对象，在保存主表对象
实例：将环境配置好，所需要的包前边已经提到过，

学生实体类：

package com.oto;

import java.util.Date;

import javax.persistence.CascadeType;
import javax.persistence.Entity;//JPA注解
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;

/*
* 学生实体类
*/
@Entity
public class Students {
private int sid; //学号
private IdCard card;//身份证
private String gender;//性别
private Date birthday;//出生日期
private String major;//专业

public Students(){

}

public Students(IdCard card,  String gender,
Date date, String major) {
//			super();
this.card = card;
this.gender = gender;
this.birthday = date;
this.major = major;
}
@Id
@GeneratedValue
public int getSid() {
return sid;
}

public void setSid(int sid) {
this.sid = sid;
}

public String getGender() {
return gender;
}

public void setGender(String gender) {
this.gender = gender;
}

public Date getBirthday() {
return birthday;
}

public void setBirthday(Date birthday) {
this.birthday = birthday;
}

public String getMajor() {
return major;
}

public void setMajor(String major) {
this.major = major;
}

@OneToOne(cascade=CascadeType.ALL)
@JoinColumn(name="pid",unique=true)
public IdCard getCard() {
return card;
}

public void setCard(IdCard card) {
this.card = card;
}

}

身份证实体类：

package com.oto;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

import org.hibernate.annotations.GenericGenerator;

@Entity
public class IdCard {
@Id
@GeneratedValue(generator="pid")
@GenericGenerator(name="pid",strategy="assigned")
@Column(length=18)
private String pid; //身份证号
private String sname;//姓名

public IdCard(){

}

public IdCard(String pid, String sname) {
this.pid = pid;
this.sname = sname;
}

public String getPid() {
return pid;
}
public void setPid(String pid) {
this.pid = pid;
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}

}

测试类：

package com.oto;

import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Test;

public class TestStudents {
@Test
public void testShemaExport(){
//创建hibernate配置对象
Configuration config = new Configuration().configure();
//创建服务注册对象
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//生成SessionFactory
SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
SchemaExport export = new SchemaExport(config);
export.create(true,true);
}
//往数据库中添加学生数据
@Test
public void addStudents(){
//创建hibernate配置对象
Configuration config = new Configuration().configure();
//创建服务注册对象
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//生成SessionFactory
SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
//创建会话
Session session = sessionFactory.getCurrentSession();
//创建事务
Transaction tx = session.beginTransaction();
IdCard card = new IdCard("123456789012345678","猪八戒");
Students stu = new Students(card,"男",new Date(),"计算机");
session.save(card);
session.save(stu);
tx.commit();
}
}

hibernate.cfg.xml中的配置：下面的使用的是同一个配置，下边的代码中不再列举，

<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
<session-factory>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<!--
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql:///hibernate_struts_stumanager</property>
-->
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/mypage</property>

<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password">root</property>
<property name="hibernate.show_sql">false</property>
<property name="hibernate.hbm2ddl.auto">create</property>
<property name="current_session_context_class">thread</property>
<!-- <mapping class="com.oto.Students"/>
<mapping class="com.oto.IdCard"/> --><!-- 一对一单向外键关联 -->

<!-- <mapping class="com.oto_11.Students"/>
<mapping class="com.oto_11.IdCard"/>  -->        <!--一对一双向外键关联  -->

<!-- <mapping class="com.mto.Students"/>
<mapping class="com.mto.ClassRoom"/> --><!--  多对一单向外键关联-->

<!-- <mapping class="com.otm.Students"/>
<mapping class="com.otm.ClassRoom"/> --><!-- 一对多单向外键关联 -->

<!-- <mapping class="com.otm_11.Students"/>
<mapping class="com.otm_11.ClassRoom"/> --><!-- 一对多双向外键 -->

<!-- <mapping class="com.mtm.Students"/>
<mapping class="com.mtm.Teachers"/>  --> <!-- 多对多单向外键关联 -->

<mapping class="com.mtm_11.Students"/>
<mapping class="com.mtm_11.Teachers"/>   <!-- 多对多双向外键关联 -->
</session-factory>
</hibernate-configuration>

一对一双向外键关联

主控方的配置同一对一单向外键关联

@OneToOne(mappedBy="card")//被控方

双向关联，必须设置mappedBy属性。因为双向关联只能交给一方去控制，不可能在双方

都设置外键保存关联关系，否则双方都无法保存

实例：
学生实体类

package com.oto_11;

import java.util.Date;

import javax.persistence.CascadeType;
import javax.persistence.Entity;//JPA注解
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;

/*
* 学生实体类
*/
@Entity
public class Students {
private int sid; //学号
private IdCard card;//身份证
private String gender;//性别
private Date birthday;//出生日期
private String major;//专业

public Students(){

}

public Students(IdCard card,  String gender,
Date date, String major) {
//			super();
this.card = card;
this.gender = gender;
this.birthday = date;
this.major = major;
}
@Id
@GeneratedValue
public int getSid() {
return sid;
}

public void setSid(int sid) {
this.sid = sid;
}

public String getGender() {
return gender;
}

public void setGender(String gender) {
this.gender = gender;
}

public Date getBirthday() {
return birthday;
}

public void setBirthday(Date birthday) {
this.birthday = birthday;
}

public String getMajor() {
return major;
}

public void setMajor(String major) {
this.major = major;
}

@OneToOne(cascade=CascadeType.ALL)
@JoinColumn(name="pid",unique=true)
public IdCard getCard() {
return card;
}

public void setCard(IdCard card) {
this.card = card;
}

}

身份证实体类：

package com.oto_11;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;

import org.hibernate.annotations.GenericGenerator;

@Entity
public class IdCard {
@Id
@GeneratedValue(generator="pid")
@GenericGenerator(name="pid",strategy="assigned")
@Column(length=18)
private String pid; //身份证号
private String sname;//姓名

@OneToOne(mappedBy="card")
private Students stu;

public IdCard(){

}

public IdCard(String pid, String sname) {
this.pid = pid;
this.sname = sname;
}

public Students getStu() {
return stu;
}

public void setStu(Students stu) {
this.stu = stu;
}

public String getPid() {
return pid;
}
public void setPid(String pid) {
this.pid = pid;
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}

}

测试类：

package com.oto_11;

import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Test;

public class TestStudents {
@Test
public void testShemaExport(){
//创建hibernate配置对象
Configuration config = new Configuration().configure();
//创建服务注册对象
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//生成SessionFactory
SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
SchemaExport export = new SchemaExport(config);
export.create(true,true);
}
@Test
public void addStudents(){
//创建hibernate配置对象
Configuration config = new Configuration().configure();
//创建服务注册对象
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//生成SessionFactory
SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
//创建会话
Session session = sessionFactory.getCurrentSession();
//创建事务
Transaction tx = session.beginTransaction();
IdCard card = new IdCard("123456789012345678","猪八戒");
Students stu = new Students(card,"男",new Date(),"计算机");
session.save(card);
session.save(stu);
tx.commit();
}
}

一对一单向外键联合主键

一对一双向外键联合主键

创建主键类

主键类必须实现serializable接口，重写hashCode()和equals()方法。

主键类

@Embeddable

实体类

@EmbeddedId

多对一单向外键关联

多方持有一方的引用

@ManyToOne(cascade={CascadeType.ALL},

fetch=FetchType.EAGER)

@JoinColumn(name="cid",referencedColumnName="CID")
学生实体类：

package com.mto;

import java.util.Date;

import javax.persistence.CascadeType;
import javax.persistence.Entity;//JPA注解
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToOne;

/*
* 学生实体类
*/
@Entity
public class Students {
private int sid; //学号
private String gender;//性别
private Date birthday;//出生日期
private String major;//专业
private ClassRoom classroom;
private String sname;

public Students(){

}

public Students(String sname,  String gender,
Date date, String major) {
//			super();
this.sname = sname;
this.gender = gender;
this.birthday = date;
this.major = major;
}
@Id
@GeneratedValue
public int getSid() {
return sid;
}

public void setSid(int sid) {
this.sid = sid;
}

public String getSname() {
return sname;
}

public void setSname(String sname) {
this.sname = sname;
}

public String getGender() {
return gender;
}

public void setGender(String gender) {
this.gender = gender;
}

public Date getBirthday() {
return birthday;
}

public void setBirthday(Date birthday) {
this.birthday = birthday;
}

public String getMajor() {
return major;
}

public void setMajor(String major) {
this.major = major;
}
@ManyToOne(cascade={CascadeType.ALL},fetch=FetchType.EAGER)
@JoinColumn(name="cid",referencedColumnName="CID")
public ClassRoom getClassroom() {
return classroom;
}

public void setClassroom(ClassRoom classroom) {
this.classroom = classroom;
}

}

班级实体类：

package com.mto;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

import org.hibernate.annotations.GenericGenerator;

//班级实体类
@Entity
public class ClassRoom {
@Id
@GeneratedValue(generator="cid")
@GenericGenerator(name="cid",strategy="assigned")
@Column(length=4)
private String cid;//班级的编号
private String cname;//班级的名字

public ClassRoom(){

}

public ClassRoom(String cid, String cname) {
this.cid = cid;
this.cname = cname;
}

public String getCid() {
return cid;
}
public void setCid(String cid) {
this.cid = cid;
}
public String getCname() {
return cname;
}
public void setCname(String cname) {
this.cname = cname;
}

}

测试类：

package com.mto;

import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Test;

public class TestStudents {
@Test
public void testShemaExport(){
//创建hibernate配置对象
Configuration config = new Configuration().configure();
//创建服务注册对象
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//生成SessionFactory
SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
SchemaExport export = new SchemaExport(config);
export.create(true,true);
}
//往数据库中添加学生数据
@Test
public void addStudents(){
//创建hibernate配置对象
Configuration config = new Configuration().configure();
//创建服务注册对象
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//生成SessionFactory
SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
//创建会话
Session session = sessionFactory.getCurrentSession();
//创建事务
Transaction tx = session.beginTransaction();
//创建班级对象
ClassRoom c1 = new ClassRoom("0001","软件工程");
ClassRoom c2 = new ClassRoom("0002","通信工程");
//创建学生对象
Students s1 = new Students("小王","男",new Date(),"计算机");
Students s2 = new Students("小黄","男",new Date(),"计算机");
Students s3 = new Students("小花","女",new Date(),"计算机");
Students s4 = new Students("小红","女",new Date(),"计算机");

s1.setClassroom(c1);
s2.setClassroom(c1);

s3.setClassroom(c2);
s4.setClassroom(c2);

session.save(c1);
session.save(c2);
session.save(s1);
session.save(s2);
session.save(s3);
session.save(s4);
tx.commit();
}
}

一对多单向外键关联

一方持有多方的集合

@OneToMany(cascade={cascadeType.ALL},fetch=FetchType.LAZY)

@JoinColumn(name="cid")

实例：
学生实体类：

package com.otm;

import java.util.Date;

import javax.persistence.CascadeType;
import javax.persistence.Entity;//JPA注解
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToOne;

/*
* 学生实体类
*/
@Entity
public class Students {
private int sid; //学号
private String gender;//性别
private Date birthday;//出生日期
private String major;//专业
private String sname;

public Students(){

}

public Students(String sname,  String gender,
Date date, String major) {
//			super();
this.sname = sname;
this.gender = gender;
this.birthday = date;
this.major = major;
}
@Id
@GeneratedValue
public int getSid() {
return sid;
}

public void setSid(int sid) {
this.sid = sid;
}

public String getSname() {
return sname;
}

public void setSname(String sname) {
this.sname = sname;
}

public String getGender() {
return gender;
}

public void setGender(String gender) {
this.gender = gender;
}

public Date getBirthday() {
return birthday;
}

public void setBirthday(Date birthday) {
this.birthday = birthday;
}

public String getMajor() {
return major;
}

public void setMajor(String major) {
this.major = major;
}

}

班级实体类：

package com.otm;

import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;

import org.hibernate.annotations.GenericGenerator;

//班级实体类
@Entity
public class ClassRoom {
@Id
@GeneratedValue(generator="cid")
@GenericGenerator(name="cid",strategy="assigned")
@Column(length=4)
private String cid;//班级的编号
private String cname;//班级的名字

@OneToMany(cascade={CascadeType.ALL},fetch=FetchType.LAZY)
@JoinColumn(name="cid")
private Set<Students> stus;//一方持有多方的集合
public ClassRoom(){

}

public ClassRoom(String cid, String cname) {
this.cid = cid;
this.cname = cname;
}

public String getCid() {
return cid;
}
public void setCid(String cid) {
this.cid = cid;
}
public String getCname() {
return cname;
}
public void setCname(String cname) {
this.cname = cname;
}

public Set<Students> getStus() {
return stus;
}

public void setStus(Set<Students> stus) {
this.stus = stus;
}

}

测试类：

package com.otm;

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

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Test;

public class TestStudents {
@Test
public void testShemaExport(){
//创建hibernate配置对象
Configuration config = new Configuration().configure();
//创建服务注册对象
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//生成SessionFactory
SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
SchemaExport export = new SchemaExport(config);
export.create(true,true);
}
@Test
public void addStudents(){
//创建hibernate配置对象
Configuration config = new Configuration().configure();
//创建服务注册对象
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//生成SessionFactory
SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
//创建会话
Session session = sessionFactory.getCurrentSession();
//创建事务
Transaction tx = session.beginTransaction();
//创建班级对象
ClassRoom c1 = new ClassRoom("0001","软件工程");
ClassRoom c2 = new ClassRoom("0002","通信工程");
//创建学生对象
Students s1 = new Students("小王","男",new Date(),"计算机");
Students s2 = new Students("小黄","男",new Date(),"计算机");
Students s3 = new Students("小花","女",new Date(),"计算机");
Students s4 = new Students("小红","女",new Date(),"计算机");

Set<Students> set1 = new HashSet<Students>();
set1.add(s1);
set1.add(s2);

Set<Students> set2 = new HashSet<Students>();
set2.add(s3);
set2.add(s4);

session.save(s1);
session.save(s2);
session.save(s3);
session.save(s4);

session.save(c1);
session.save(c2);
tx.commit();
}
}

一对多双向外键关联

多方：多方持有一方的引用

@ManyToOne(cascade={CascadeType.ALL},fetch=FetchType.EAGER)

@JoinColumn(name="cid")

一方：一方持有多方的集合

@OneToMany(cascade={CascadeType.ALL},fetch=FetchType.LAZY)

@JoinColumn(name="cid")

实例：

package com.otm_11;

import java.util.Date;

import javax.persistence.CascadeType;
import javax.persistence.Entity;//JPA注解
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToOne;

/*
* 学生实体类
*/
@Entity
public class Students {
private int sid; //学号
private String gender;//性别
private Date birthday;//出生日期
private String major;//专业
private String sname;//姓名
private ClassRoom classroom;
public Students(){

}

public Students(String sname,  String gender,
Date date, String major) {
//			super();
this.sname = sname;
this.gender = gender;
this.birthday = date;
this.major = major;
}
@Id
@GeneratedValue
public int getSid() {
return sid;
}

public void setSid(int sid) {
this.sid = sid;
}

public String getSname() {
return sname;
}

public void setSname(String sname) {
this.sname = sname;
}

public String getGender() {
return gender;
}

public void setGender(String gender) {
this.gender = gender;
}

public Date getBirthday() {
return birthday;
}

public void setBirthday(Date birthday) {
this.birthday = birthday;
}

public String getMajor() {
return major;
}

public void setMajor(String major) {
this.major = major;
}
@ManyToOne(cascade={CascadeType.ALL},fetch=FetchType.EAGER)
@JoinColumn(name="cid")
public ClassRoom getClassroom() {
return classroom;
}

public void setClassroom(ClassRoom classroom) {
this.classroom = classroom;
}

}

班级实体类：

package com.otm_11;

import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;

import org.hibernate.annotations.GenericGenerator;

//班级实体类
@Entity
public class ClassRoom {
@Id
@GeneratedValue(generator="cid")
@GenericGenerator(name="cid",strategy="assigned")
@Column(length=4)
private String cid;//班级的编号
private String cname;//班级的名字

@OneToMany(cascade={CascadeType.ALL},fetch=FetchType.LAZY)
@JoinColumn(name="cid")
private Set<Students> stus;//一方持有多方的集合
public ClassRoom(){

}

public ClassRoom(String cid, String cname) {
this.cid = cid;
this.cname = cname;
}

public String getCid() {
return cid;
}
public void setCid(String cid) {
this.cid = cid;
}
public String getCname() {
return cname;
}
public void setCname(String cname) {
this.cname = cname;
}

public Set<Students> getStus() {
return stus;
}

public void setStus(Set<Students> stus) {
this.stus = stus;
}

}

测试类：

package com.mto_11;

import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Test;

import com.otm_11.ClassRoom;
import com.otm_11.Students;

public class TestStudents {
@Test
public void testShemaExport(){
//创建hibernate配置对象
Configuration config = new Configuration().configure();
//创建服务注册对象
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//生成SessionFactory
SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
SchemaExport export = new SchemaExport(config);
export.create(true,true);
}
@Test
public void addStudents(){
//创建hibernate配置对象
Configuration config = new Configuration().configure();
//创建服务注册对象
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//生成SessionFactory
SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
//创建会话
Session session = sessionFactory.getCurrentSession();
//创建事务
Transaction tx = session.beginTransaction();
//创建班级对象
ClassRoom c1 = new ClassRoom("0001","软件工程");
ClassRoom c2 = new ClassRoom("0002","通信工程");
//创建学生对象
Students s1 = new Students("小王","男",new Date(),"计算机");
Students s2 = new Students("小黄","男",new Date(),"计算机");
Students s3 = new Students("小花","女",new Date(),"计算机");
Students s4 = new Students("小红","女",new Date(),"计算机");

s1.setClassroom(c1);
s2.setClassroom(c1);

s3.setClassroom(c2);
s4.setClassroom(c2);

session.save(c1);
session.save(c2);
session.save(s1);
session.save(s2);
session.save(s3);
session.save(s4);
tx.commit();
}
}

多对多单向外键关联

其中一个多方持有另一个多方的集合对象

创建中间表

@MantToMany

@JoinTable(

name="teachers_students",

joinColumns={@JoinColumn(name="sid")},inverseJoinColumns={@JoinColumn(name="tid")}

)

实例：
学生实体类：

package com.mtm;

import java.util.Date;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Entity;//JPA注解
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.ManyToOne;
import javax.persistence.OneToOne;

/*
* 学生实体类
*/
@Entity
public class Students {
private int sid; //学号
private String gender;//性别
private Date birthday;//出生日期
private String major;//专业
private String sname;//学生姓名
private Set<Teachers> teachers; //学生持有教师的集合

public Students(){

}

public Students(String sname,  String gender,
Date date, String major) {
//			super();
this.sname = sname;
this.gender = gender;
this.birthday = date;
this.major = major;
}
@Id
@GeneratedValue
public int getSid() {
return sid;
}

public void setSid(int sid) {
this.sid = sid;
}

public String getSname() {
return sname;
}

public void setSname(String sname) {
this.sname = sname;
}

public String getGender() {
return gender;
}

public void setGender(String gender) {
this.gender = gender;
}

public Date getBirthday() {
return birthday;
}

public void setBirthday(Date birthday) {
this.birthday = birthday;
}

public String getMajor() {
return major;
}

public void setMajor(String major) {
this.major = major;
}
@ManyToMany
@JoinTable(
name="teachers_students",
joinColumns={@JoinColumn(name="sid")},
inverseJoinColumns={@JoinColumn(name="tid")}
)
public Set<Teachers> getTeachers() {
return teachers;
}

public void setTeachers(Set<Teachers> teachers) {
this.teachers = teachers;
}

}

老师实体类：

package com.mtm;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

import org.hibernate.annotations.GenericGenerator;

//教师实体类
@Entity
public class Teachers {
@Id
@GeneratedValue(generator="tid")
@GenericGenerator(name="tid",strategy="assigned")
@Column(length=4)
private String tid;//教师id
private String tname;//教师名字

public Teachers(){

}

public Teachers(String tid, String tname) {
//			super();
this.tid = tid;
this.tname = tname;
}

public String getTid() {
return tid;
}
public void setTid(String tid) {
this.tid = tid;
}
public String getTname() {
return tname;
}
public void setTname(String tname) {
this.tname = tname;
}

}

测试类：

package com.mtm;

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

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Test;

public class TestStudents {
@Test
public void testShemaExport(){
//创建hibernate配置对象
Configuration config = new Configuration().configure();
//创建服务注册对象
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//生成SessionFactory
SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
SchemaExport export = new SchemaExport(config);
export.create(true,true);
}
@Test
public void addStudents(){
//创建hibernate配置对象
Configuration config = new Configuration().configure();
//创建服务注册对象
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//生成SessionFactory
SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
Session session = sessionFactory.getCurrentSession();
Transaction tx = session.beginTransaction();

//创建教师对象
Teachers t1 = new Teachers("0001","张老师");
Teachers t2 = new Teachers("0002","黄老师");
Teachers t3 = new Teachers("0003","李老师");
Teachers t4 = new Teachers("0004","王老师");

Students s1 = new Students("张三","男",new Date(),"计算机");
Students s2 = new Students("李四","男",new Date(),"计算机");
Students s3 = new Students("王五","女",new Date(),"通信");
Students s4 = new Students("赵六","女",new Date(),"通信");

Set<Teachers> set1 = new HashSet<Teachers>();
set1.add(t1);
set1.add(t2);

Set<Teachers> set2 = new HashSet<Teachers>();
set2.add(t3);
set2.add(t4);

Set<Teachers> set3 = new HashSet<Teachers>();
set3.add(t1);
set3.add(t3);
set3.add(t4);

Set<Teachers> set4 = new HashSet<Teachers>();
set4.add(t2);
set4.add(t3);
set4.add(t4);

s1.setTeachers(set1);
s2.setTeachers(set2);
s3.setTeachers(set3);
s4.setTeachers(set4);

session.save(t1);
session.save(t2);
session.save(t3);
session.save(t4);

session.save(s1);
session.save(s2);
session.save(s3);
session.save(s4);

tx.commit();
}
}

多对多双向外键关联

双方持有对方的集合对象，其中一方设置

//教师类

@ManyToMany(mappedBy="teachers")

另一方

//学生类

@ManyToMany

@JoinTable(

name="teachers_students",

joinColumns={@JoinColumn(name="sid")},

inverseJoinColumns={@JoinColumn(name="tid")}

)

实例：
学生实体类：

package com.mtm_11;

import java.util.Date;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Entity;//JPA注解
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.ManyToOne;
import javax.persistence.OneToOne;

/*
* 学生实体类
*/
@Entity
public class Students {
private int sid; //学号
private String gender;//性别
private Date birthday;//出生日期
private String major;//专业
private String sname;//学生姓名
private Set<Teachers> teachers; //学生持有教师的集合

public Students(){

}

public Students(String sname,  String gender,
Date date, String major) {
//			super();
this.sname = sname;
this.gender = gender;
this.birthday = date;
this.major = major;
}
@Id
@GeneratedValue
public int getSid() {
return sid;
}

public void setSid(int sid) {
this.sid = sid;
}

public String getSname() {
return sname;
}

public void setSname(String sname) {
this.sname = sname;
}

public String getGender() {
return gender;
}

public void setGender(String gender) {
this.gender = gender;
}

public Date getBirthday() {
return birthday;
}

public void setBirthday(Date birthday) {
this.birthday = birthday;
}

public String getMajor() {
return major;
}

public void setMajor(String major) {
this.major = major;
}
@ManyToMany
@JoinTable(
name="teachers_students",
joinColumns={@JoinColumn(name="sid")},
inverseJoinColumns={@JoinColumn(name="tid")}
)
public Set<Teachers> getTeachers() {
return teachers;
}

public void setTeachers(Set<Teachers> teachers) {
this.teachers = teachers;
}

}

老师实体类：

package com.mtm_11;

import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.ManyToMany;

import org.hibernate.annotations.GenericGenerator;

//教师实体类
@Entity
public class Teachers {
@Id
@GeneratedValue(generator="tid")
@GenericGenerator(name="tid",strategy="assigned")
@Column(length=4)
private String tid;//教师id
private String tname;//教师名字

@ManyToMany(mappedBy="teachers")
private Set<Students> stus;//教师持有学生的集合

public Teachers(){

}

public Teachers(String tid, String tname) {
//			super();
this.tid = tid;
this.tname = tname;
}

public String getTid() {
return tid;
}
public void setTid(String tid) {
this.tid = tid;
}
public String getTname() {
return tname;
}
public void setTname(String tname) {
this.tname = tname;
}

}

测试类：

package com.mtm_11;

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

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Test;

public class TestStudents {
@Test
public void testShemaExport(){
//创建hibernate配置对象
Configuration config = new Configuration().configure();
//创建服务注册对象
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//生成SessionFactory
SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
SchemaExport export = new SchemaExport(config);
export.create(true,true);
}
@Test
public void addStudents(){
//创建hibernate配置对象
Configuration config = new Configuration().configure();
//创建服务注册对象
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//生成SessionFactory
SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
Session session = sessionFactory.getCurrentSession();
Transaction tx = session.beginTransaction();

//创建教师对象
Teachers t1 = new Teachers("0001","张老师");
Teachers t2 = new Teachers("0002","黄老师");
Teachers t3 = new Teachers("0003","李老师");
Teachers t4 = new Teachers("0004","王老师");

Students s1 = new Students("张三","男",new Date(),"计算机");
Students s2 = new Students("李四","男",new Date(),"计算机");
Students s3 = new Students("王五","女",new Date(),"通信");
Students s4 = new Students("赵六","女",new Date(),"通信");

Set<Teachers> set1 = new HashSet<Teachers>();
set1.add(t1);
set1.add(t2);

Set<Teachers> set2 = new HashSet<Teachers>();
set2.add(t3);
set2.add(t4);

Set<Teachers> set3 = new HashSet<Teachers>();
set3.add(t1);
set3.add(t3);
set3.add(t4);

Set<Teachers> set4 = new HashSet<Teachers>();
set4.add(t2);
set4.add(t3);
set4.add(t4);

s1.setTeachers(set1);
s2.setTeachers(set2);
s3.setTeachers(set3);
s4.setTeachers(set4);

session.save(t1);
session.save(t2);
session.save(t3);
session.save(t4);

session.save(s1);
session.save(s2);
session.save(s3);
session.save(s4);

tx.commit();
}
}

这里列举了几个简单的例子，大神直接略过啊~~~~