hibernate学习（设计多对多 关系 映射）

//
package org.crazy.app.domain;
import java.util.HashSet;
import java.util.Set;

import javax.persistence.*;
@Entity
@Table(name="person_inf")
public class Person {
    @Id
    @Column(name="person_id")
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer id;
    private String name;
    private int age;
    @ManyToMany(targetEntity=Address.class)
    @JoinTable(name="person_address",
    joinColumns=@JoinColumn(name="person_id",referencedColumnName="person_id"),
    inverseJoinColumns=@JoinColumn(name="address_id",referencedColumnName="address_id"))
    private Set<Address> address=new HashSet<Address>();
    
    public Person() {
    
    }
    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }
    //
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public Set<Address> getAddress() {
        return address;
    }
    public void setAddress(Set<Address> address) {
        this.address = address;
    }
    
    
    
}
//**************************************
package org.crazy.app.domain;

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

import javax.persistence.*;

@Entity
@Table(name="address_inf")
public class Address {
    @Id
    @Column(name="address_id")
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer addressId;
    private String addressDetail;
    @ManyToMany(targetEntity=Person.class)
    @JoinTable(name="person_address",
    joinColumns=@JoinColumn(name="address_id",referencedColumnName="address_id"),
    inverseJoinColumns=@JoinColumn(name="person_id",referencedColumnName="person_id"))
    private Set<Person> persons=new HashSet<Person>();
    public String getAddressDetail() {
        return addressDetail;
    }
    public void setAddressDetail(String addressDetail) {
        this.addressDetail = addressDetail;
    }
    public Set<Person> getPersons() {
        return persons;
    }
    public void setPersons(Set<Person> persons) {
        this.persons = persons;
    }
    public Address(String addressDetail) {
        this.addressDetail = addressDetail;
    }
    public Address() {
    
    }
    
    
    
}

        Person p = new Person();
        // 设置Person的name为crazyit
        p.setName("crazyit");
        p.setAge(20);
        // 持久化Person对象(对应于插入主表记录)
        session.save(p);
        // 创建一个瞬态的Address对象
        Address a = new Address("广州天河");
        // 先设置Person和Address之间的关联关系
        a.getPersons().add(p);
        // 再持久化Address对象
        session.persist(a);
        // 创建一个瞬态的Address对象
        Address a2 = new Address("上海虹口");
        // 先设置Person和Address之间的关联关系
        a2.getPersons().add(p);
        // 再持久化Address对象(对应于插入从表记录)
        session.persist(a2);

        Person p2 = new Person();
        p2.setName("fkit");
        p2.setAge(29);
        p2.getAddress().add(a2);
        session.save(p2);