JPA OneToMany 映射问题

Question

          字段名          数据类型        数据长度
省表 tb_province
省编号 id         int         4
省名 provinceName varchar(8) 1
市表 tb_city
城市编号 id         int           4
城市名 cityName        varchar(8)      1
外键 provinceId         int         4这两天在学习JPA OneToMany 映射问题，可是在网上找了好多资料，也没有看明白，网上的示例又太少，所以弄了上面的两个关联表，希望有朋友可以给予一下指点，对这两个表在ELIPASE下写类进行OneToMany映射，在此先谢谢了。

Answer 1

package com.family168.domain;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;
@Entity
public class Child {
    private Long id;
    private String name;
    private Parent parent;    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    public Long getId() {
        return id;
    }    public void setId(Long id) {
        this.id = id;
    }    @Column
    public String getName() {
        return name;
    }    public void setName(String name) {
        this.name = name;
    }    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "PARENT_ID")
    public Parent getParent() {
        return parent;
    }    public void setParent(Parent parent) {
        this.parent = parent;
    }
}package com.family168.domain;import java.util.HashSet;
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.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.OrderBy;
@Entity
public class Parent {
    private Long id;
    private String name;
    private Set<Child> children = new HashSet<Child>(0);    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    public Long getId() {
        return id;
    }    public void setId(Long id) {
        this.id = id;
    }    @Column
    public String getName() {
        return name;
    }    public void setName(String name) {
        this.name = name;
    }    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "parent")
    @OrderBy("id asc")
    public Set<Child> getChildren() {
        return children;
    }    public void setChildren(Set<Child> children) {
        this.children = children;
    }
}