商品与评论关系的一对多

表结构设计

t_goods:

商品表

t_comment：

评论表

商品(一的一方）

package com.project.bean;

import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;

/**
 * 商品与评论的一对多关系
 * @author wqj24
 *
 */

@Entity
@Table(name="t_goods")
public class GoodsBean {
    
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    @Column(name="g_id")
    private int id;
    @Column(name="g_name")
    private String name;
    @Column(name="g_price")
    private double price;
    @Column(name="g_type")
    private String type;
    
    /*
     * mappedBy：在一对多关系中，一的一方写，表示有对方维护关联关系，值应该为对方的对象变量
     * cascade：开启级联
     */
    @OneToMany(mappedBy="goods", cascade=CascadeType.ALL)
    private Set<CommentBean> comSet;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public Set<CommentBean> getComSet() {
        return comSet;
    }

    public void setComSet(Set<CommentBean> comSet) {
        this.comSet = comSet;
    }

    @Override
    public String toString() {
        return "GoodsBean [id=" + id + ", name=" + name + ", price=" + price + ", type=" + type + ", comSet=" + comSet
                + "]";
    }

}

商品的评论（多的一方)

package com.project.bean;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

@Entity
@Table(name="t_stu")
public class StudentBean {

    private int id;
    private String name;
    private ClassBean cla = new ClassBean();;
    
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="s_id")
    public int getId() {
        return id;
    }

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

    public void setName(String name) {
        this.name = name;
    }
    
    @ManyToOne(fetch=FetchType.LAZY,cascade=CascadeType.ALL)
    //指定外键的名称
    @JoinColumn(name="o_u_id")
    public ClassBean getCla() {
        return cla;
    }

    public void setCla(ClassBean cla) {
        this.cla = cla;
    }

    @Override
    public String toString() {
        return "StudentBean [id=" + id + ", name=" + name + "]";
    }

}