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 */@Entitypublic 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;@Entitypublic 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@Testpublic 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 */@Entitypublic 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;@Entitypublic 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);    }@Testpublic 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 */@Entitypublic 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@Entitypublic 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@Testpublic 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 */@Entitypublic 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@Entitypublic 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);    }@Testpublic 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 */@Entitypublic 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@Entitypublic 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);    }@Testpublic 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 */@Entitypublic 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@Entitypublic 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);    }@Testpublic 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 */@Entitypublic 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@Entitypublic 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);    }@Testpublic 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~~~~