JPA修改树结构的关联关系

JPA修改树结构的关联关系：
JAP默认是以主键和parent字段自动形成树结构，当添加children属性后，查询时自动会将父节点下的子节点组装到children属性中，
但是如果是非主键字段和parent字段形成树结构的话，需要手动去指定其关系eg:

　　　　@OneToMany(fetch = FetchType.EAGER)
        @JoinColumn(name = "parent_id",referencedColumnName = "id")
        @JoinColumn(name = "station_code",referencedColumnName = "station_code")
        private Set<myTree> children;

其中@JoinColumn注解用来指定与所操作实体相关联的数据库表中的列字段；
@OneToMany用来建立一对多的关系映射，用于指定与之关联的多个实体；
id为非主键字段，并且不同的station_code对应的id会重复，所以又添加了station_code关联字段。

package com.cars.ict.rbpsems.entity.controlpisled;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import lombok.Data;
import org.hibernate.annotations.GenericGenerator;
import javax.persistence.*;
import java.io.Serializable;
import java.util.Set;

@Entity
@Table(name = "my_tree")
@JsonIgnoreProperties(value = {"hibernateLazyInitializer", "handler", "fieldHandler"})
public class myTree implements Serializable {

        @Id
        @Column(length = 50, name = "ids")
        private String ids;

        //id不再为主键
        @Column(length = 50, name = "id")
        private String id;

        @Column(length = 50, name = "rela_tree_id")
        private String relaTreeId;

        /**
         * 上級
         */
    //    @JsonIgnore
    //    @ManyToOne(fetch = FetchType.LAZY)
        @Column(name = "parent_id")
        private String parent;

----------------------------旧的写法--------------------------------

      //@OneToMany(fetch = FetchType.EAGER, mappedBy = "parent")
      //@OrderBy(value = "code asc")
      //private Set<StationRegionTree> children;

---------------------------------------------------------------------

//==========================绑定新的关系，以id和station_code为关联条件=================
        @OneToMany(fetch = FetchType.EAGER)
        @JoinColumn(name = "parent_id",referencedColumnName = "id")
        @JoinColumn(name = "station_code",referencedColumnName = "station_code")
        //@OrderBy(value = "code asc")
        private Set<myTree> children;

//======================================================================================

        /**
         * 基础信息值
         */
        @Column(length = 20, name = "inf_value")
        private String infValue;
        /**
         * 基础信息编码(简称)
         */
        @Column(length = 500, name = "inf_code")
        private String infCode;
        /**
         * 基础信息类型
         */
        @Column(length = 2, name = "inf_type")
        private String infType;
        /**
         * 基础信息名称
         */
        @Column(length = 20, name = "inf_name")
        private String infName;
        /**
         * 名称
         */
        @Column(length = 20, name = "station_name")
        private String stationName;
        /**
         * 基础信息标示
         */
        @Column(length = 100, name = "inf_mark")
        private String infMark;
        /**
         * 信息状态　
         */
        @Column(length = 1, name = "rela_tree_state")
        private String relaTreeState;

        /**
         * 车编码　
         */
        @Column(length = 20, name = "station_code")
        private String stationCode;

        /**
         * 区域是否被监控管理
         */
        @Column(name = "s_ismonitored")
        private String ismonitored;