Hibernate框架中一对多的双向关系举例！

1.首先配置好Hibernate的运行环境-------hibernate jar 包，Mysql jar包；

2.编写两个实体类，分别是City ,Province，使用@Annotation声明两者一对多的关系：

3.配置hibernate.cfg.xml文件，包括 DataSource,方言等属性，ORM关系

package com.liyin.manytoone;

import javax.persistence.Column;

@Entity
@Table(name="tb_city")
public class City {
    
    private int id;
    private String name;
    private Province province;
    
    public City(){
        
    }
    @Id
    @GeneratedValue
    @Column(name="id")
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }
    @Column(name="name")
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
    @ManyToOne
    @JoinColumn(name="prov_id")
    public Province getProvince() {
        return province;
    }

    public void setProvince(Province province) {
        this.province = province;
    }
    
    

}

package com.liyin.manytoone;

import java.util.Set;
@Entity
@Table(name="tb_province")

public class Province {
    
    private int id;
    private String name;
    private Set<City>citys;
    
    public Province(){
        
    }
    @Id
    @GeneratedValue
    @Column(name="id")
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    @Column(name="name")
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @OneToMany(mappedBy="province")//声明一对多关系
    public Set<City> getCitys() {
        return citys;
    }
    public void setCitys(Set<City> citys) {
        this.citys = citys;
    }
}