java List转tree

最新推荐文章于 2024-04-24 09:14:49 发布

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最新推荐文章于 2024-04-24 09:14:49 发布

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文章标签： java

本文链接：https://blog.youkuaiyun.com/weixin_42502300/article/details/117216250

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本文介绍了如何使用Spring Boot的MyBatis Plus框架，通过Java代码实现数据库中机构树结构的遍历和构建，包括实体类定义、listToTree方法的循环构建以及getRootParent和createChildren辅助函数。

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1、数据库实体类：



import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;

import java.util.ArrayList;
import java.util.List;

@Data
@ApiModel(value="机构树结构", description="机构树结构")
public class OrganizationTree {

    private Long id;
    /**
     * 机构编码
     */
    @ApiModelProperty(value = "机构编码")
    private String orgCode;
    /**
     * 机构名称
     */
    @ApiModelProperty(value = "机构名称")
    private String orgName;
    /**
     * 父机构id
     */
    @ApiModelProperty(value = "子机构")
    private List<OrganizationTree> children=new ArrayList<>();
}

2、树实体类：



import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;

import java.util.ArrayList;
import java.util.List;

@Data
@ApiModel(value="机构树结构", description="机构树结构")
public class OrganizationTree {

    private Long id;
    /**
     * 机构编码
     */
    @ApiModelProperty(value = "机构编码")
    private String orgCode;
    /**
     * 机构名称
     */
    @ApiModelProperty(value = "机构名称")
    private String orgName;
    /**
     * 父机构id
     */
    @ApiModelProperty(value = "子机构")
    private List<OrganizationTree> children=new ArrayList<>();
}

3、循环构建树

     /**
     * 根据pid将列表转成树结构
     * @param organizationEntityList
     * @return
     */
    private List<OrganizationTree> listToTree(List<OrganizationEntity> organizationEntityList){
        List<OrganizationEntity> rootList=getRootParent(organizationEntityList,-1L);
        List<OrganizationTree> organizationTreeList=new ArrayList<>();
        ListUtil.copyList(rootList,organizationTreeList,OrganizationTree.class);
        return createChildren(organizationTreeList,organizationEntityList);
    }

    /**
     * 循环构建children
     * @param organizationTreeList
     */
    private List<OrganizationTree> createChildren(List<OrganizationTree> organizationTreeList,List<OrganizationEntity> rootList){
        for(OrganizationTree tree:organizationTreeList){
            List<OrganizationEntity> organizationEntityList=getRootParent(rootList,tree.getId());
            if(organizationEntityList!=null&&organizationEntityList.size()>0){
                List<OrganizationTree> organizationTrees=new ArrayList<>();
                ListUtil.copyList(organizationEntityList,organizationTrees,OrganizationTree.class);
                tree.setChildren(organizationTrees);
                createChildren(tree.getChildren(),rootList);
            }
        }
        return organizationTreeList;
    }

    /**
     * 找到列表中所有的顶级节点
     * @param organizationEntityList
     * @return
     */
    private List<OrganizationEntity> getRootParent(List<OrganizationEntity> organizationEntityList,Long pid){
        List<OrganizationEntity> list=new ArrayList<>();
        for(OrganizationEntity organizationEntity:organizationEntityList){
            if(pid==organizationEntity.getPid()){
                list.add(organizationEntity);
            }
        }
        organizationEntityList.removeAll(list);
        return list;
    }