java将list转为树形结构

目录

• 1、通过转化成json封装数据
• 2、通过java8 stream转换

 

1、通过转化成json封装数据

原始数据如下

[
    {
        "name":"甘肃省",
        "pid":0,
        "id":1
    },
    {
        "name":"天水市",
        "pid":1,
        "id":2
    },
    {
        "name":"秦州区",
        "pid":2,
        "id":3
    },
    {
        "name":"北京市",
        "pid":0,
        "id":4
    },
    {
        "name":"昌平区",
        "pid":4,
        "id":5
    }
]

现需要是使用java将以上数据转为树形结构，转化后下的结构如下

[
    {
        "children":[
            {
                "children":[
                    {
                        "name":"秦州区",
                        "pid":2,
                        "id":3
                    }
                ],
                "name":"天水市",
                "pid":1,
                "id":2
            }
        ],
        "name":"甘肃省",
        "pid":0,
        "id":1
    },
    {
        "children":[
            {
                "name":"昌平区",
                "pid":4,
                "id":5
            }
        ],
        "name":"北京市",
        "pid":0,
        "id":4
    }
]

代码如下

/**

- listToTree
- <p>方法说明<p>
- 将JSONArray数组转为树状结构
- @param arr 需要转化的数据
- @param id 数据唯一的标识键值
- @param pid 父id唯一标识键值
- @param child 子节点键值
- @return JSONArray
*/
public static JSONArray listToTree(JSONArray arr,String id,String pid,String child){
   JSONArray r = new JSONArray();
   JSONObject hash = new JSONObject();
   //将数组转为Object的形式，key为数组中的id
   for(int i=0;i<arr.size();i++){
  JSONObject json = (JSONObject) arr.get(i);
  hash.put(json.getString(id), json);
   }
   //遍历结果集
   for(int j=0;j<arr.size();j++){
  //单条记录
  JSONObject aVal = (JSONObject) arr.get(j);
  //在hash中取出key为单条记录中pid的值
  JSONObject hashVP = (JSONObject) hash.get(aVal.get(pid).toString());
  //如果记录的pid存在，则说明它有父节点，将她添加到孩子节点的集合中
  if(hashVP!=null){
     //检查是否有child属性
     if(hashVP.get(child)!=null){
        JSONArray ch = (JSONArray) hashVP.get(child);
        ch.add(aVal);
        hashVP.put(child, ch);
     }else{
        JSONArray ch = new JSONArray();
        ch.add(aVal);
        hashVP.put(child, ch);
     }
  }else{
     r.add(aVal);
  }
   }
   return r;
}
测试代码如下
public static void main(String[] args){
   List<Map<String,Object>> data = new ArrayList<>();
   Map<String,Object> map = new HashMap<>();
   map.put("id",1);
   map.put("pid",0);
   map.put("name","甘肃省");
   data.add(map);
   Map<String,Object> map2 = new HashMap<>();
   map2.put("id",2);
   map2.put("pid",1);
   map2.put("name","天水市");
   data.add(map2);
   Map<String,Object> map3 = new HashMap<>();
   map3.put("id",3);
   map3.put("pid",2);
   map3.put("name","秦州区");
   data.add(map3);
   Map<String,Object> map4 = new HashMap<>();
   map4.put("id",4);
   map4.put("pid",0);
   map4.put("name","北京市");
   data.add(map4);
   Map<String,Object> map5 = new HashMap<>();
   map5.put("id",5);
   map5.put("pid",4);
   map5.put("name","昌平区");
   data.add(map5);
   System.out.println(JSON.toJSONString(data));
   JSONArray result = listToTree(JSONArray.parseArray(JSON.toJSONString(data)),"id","pid","children");
   System.out.println(JSON.toJSONString(result));
}

2、通过java8 stream转换

我在网上找了很多方法，自己写的这个思路清晰，代码量少，希望能找到志同道合的朋友，看看还有没有优化的地方。

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
@Data
@AllArgsConstructor
@NoArgsConstructor
public class ZhField {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private String id;

    /**
     * 上级领域id
     */
    @Column(name = "parent_id")
    private String parentId;

    /**
     * 领域名称
     */
    private String name;

    /**
     * 排序
     */
    private Integer sort;

}

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.io.Serializable;
import java.util.List;
import java.util.Map;


@Data
@AllArgsConstructor
@NoArgsConstructor
public class TreeMenuNode implements Serializable {
	private String id;
	private String parentId;
	private String name;
	private Integer sort;
	private List<TreeMenuNode> children;
	private Boolean isAble;

	/**20180929zhw添加 树的额外属性(至少含有父节点ID:"parentId")**/
	private Map<String,Object> attributes;
}

package com.egaoqi.service.impl.company;

import com.egaoqi.entity.ZhField;
import com.egaoqi.util.TreeMenuNode;

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

/**
 * @author zhizhao
 * @description
 * @create 2018-11-14 9:07
 */
public class toModel {

    private static void forEach(Map<String, List<TreeMenuNode>> collect, TreeMenuNode treeMenuNode) {
        List<TreeMenuNode> treeMenuNodes = collect.get(treeMenuNode.getId());
        if(collect.get(treeMenuNode.getId())!=null){
            //排序
            treeMenuNodes.sort((u1, u2) -> u1.getSort().compareTo(u2.getSort()));
            treeMenuNodes.stream().sorted(Comparator.comparing(TreeMenuNode::getSort)).collect(Collectors.toList());
            treeMenuNode.setChildren(treeMenuNodes);
            treeMenuNode.getChildren().forEach(t->{
                forEach(collect,t);
            });
        }
    }

    public static void main(String[] args) {
        List<ZhField> zhFields = new ArrayList<>();
        List<TreeMenuNode> treeNodeList = new ArrayList<>();
        //转换数据,这个是前端需要的格式。
        zhFields.forEach(t->{
            TreeMenuNode treeMenuNode = new TreeMenuNode();
            treeMenuNode.setId(t.getId());
            treeMenuNode.setParentId(t.getParentId());
            treeMenuNode.setName(t.getName());
            treeMenuNode.setSort(t.getSort());
            treeNodeList.add(treeMenuNode);
        });
        //分组
        Map<String, List<TreeMenuNode>> collect = treeNodeList.stream().collect(Collectors.groupingBy(TreeMenuNode::getParentId));
        //树形结构 肯定有一个根部，我的这个根部的就是parentId.euqal("0"),而且只有一个就get（"0"）
        TreeMenuNode treeMenuNode = collect.get("0").get(0);
        //拼接数据
        forEach(collect, treeMenuNode);
    }
}



my

package com.hainei.service.impl.wp.jgzz;

import com.hainei.common.constants.BaseConstant;
import com.hainei.common.enums.YesOrNo;
import com.hainei.common.token.JwtTokenUtil;
import com.hainei.common.tree.TreeObject;
import com.hainei.common.tree.TreeService;
import com.hainei.common.tree.myTree.ToModel;
import com.hainei.common.tree.myTree.TreeMenuNode;
import com.hainei.common.tree.myTree.ZhField;
import com.hainei.mapper.base.BaseUserMapper;
import com.hainei.mapper.wp.jgzz.WpJgzzAqglwlMapper;
import com.hainei.mapper.wp.sbgl.WpYfbyjlMapper;
import com.hainei.pojo.bo.wp.jgzz.WpJgzzAqglwlBO;
import com.hainei.pojo.bo.wp.sbgl.WpYfbyBO;
import com.hainei.pojo.model.wp.jgzz.WpJgzzAqglwl;
import com.hainei.pojo.model.wp.sbgl.WpYfby;
import com.hainei.pojo.model.wp.sbgl.WpYfbyjl;
import com.hainei.pojo.vo.base.BaseTreeOrganizationWithRolesVO;
import com.hainei.pojo.vo.wp.jgzz.WpAqglwlVO;
import com.hainei.pojo.vo.wp.sbgl.WpYfbyVO;
import com.hainei.service.base.BaseDataTableService;
import com.hainei.service.base.BaseOrganizationService;
import com.hainei.service.wp.jgzz.WpAqglwlService;
import com.hainei.service.wp.zyaqgl.WpZypNumService;
import org.apache.commons.collections.CollectionUtils;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.servlet.http.HttpServletRequest;
import java.util.*;
import java.util.stream.Collectors;

/**
 * Created with IntelliJ IDEA.
 * User：wq
 * Date：2021/1/8
 * Time: 15:53
 * Description: 目标职责
 */
@Service
@Transactional
public class WpAqglwlServiceImpl implements WpAqglwlService {
    @Autowired
    private WpJgzzAqglwlMapper jgzzAqglwlMapper;
    @Autowired
    private WpYfbyjlMapper wpYfbyjlMapper;
    @Autowired
    private HttpServletRequest request;
    @Autowired
    private BaseOrganizationService organizationService;
    @Autowired
    private BaseDataTableService dataTableService;
    @Autowired
    private WpZypNumService zypNumService;
    @Autowired
    private BaseUserMapper userMapper;

    @Override
    public void addRecord(WpJgzzAqglwlBO wpJgzzAqglwlBO) {
        String token = request.getHeader(BaseConstant.ACCESS_TOKEN);
        String userId = JwtTokenUtil.getUserId(token);
        String id = UUID.randomUUID().toString().replaceAll("-", "");
        WpJgzzAqglwl wpJgzzAqglwl = new WpJgzzAqglwl();
        BeanUtils.copyProperties(wpJgzzAqglwlBO, wpJgzzAqglwl);
        wpJgzzAqglwl.setId(id);
        //wpYfby.setFileNum(zypNumService.getZypNum("AQWJ"));
        wpJgzzAqglwl.setIsDeleted(YesOrNo.NO.type);
        wpJgzzAqglwl.setGmtCreatedOn(new Date());
        wpJgzzAqglwl.setGmtCreatedBy(userId);
        //添加数据权限表
        Set<String> organizationIdsByUserId = organizationService.getOrganizationIdsByUserId(userId);
        //3.插入数据权限
        dataTableService.insert(organizationIdsByUserId, id);
        jgzzAqglwlMapper.insertSelective(wpJgzzAqglwl);
    }

    @Override
    public void deleteByIds(List<String> ids) {
        for (String id :
                ids) {
            WpJgzzAqglwl wpJgzzAqglwl = new WpJgzzAqglwl();
            wpJgzzAqglwl.setId(id);
            wpJgzzAqglwl.setIsDeleted(YesOrNo.YES.type);
            jgzzAqglwlMapper.updateByPrimaryKeySelective(wpJgzzAqglwl);
        }
    }

    @Override
    public void updateRecord(WpJgzzAqglwlBO wpJgzzAqglwlBO) {
        String token = request.getHeader(BaseConstant.ACCESS_TOKEN);
        String userId = JwtTokenUtil.getUserId(token);
        WpJgzzAqglwl wpJgzzAqglwl = new WpJgzzAqglwl();
        wpJgzzAqglwl.setGmtUpdatedBy(userId);
        BeanUtils.copyProperties(wpJgzzAqglwlBO, wpJgzzAqglwl);
        jgzzAqglwlMapper.updateByPrimaryKeySelective(wpJgzzAqglwl);
    }

    @Override
    public Map<String,Object> getById(String id) {
        Map byId = jgzzAqglwlMapper.getById(id);
       // putWfValue(byId);
        return byId;
    }

    @Override
    public List<TreeMenuNode> listAll(WpJgzzAqglwlBO wpJgzzAqglwlBO) {
        String token = request.getHeader(BaseConstant.ACCESS_TOKEN);
        String userId = JwtTokenUtil.getUserId(token);
        Collection<TreeObject<WpAqglwlVO>> treeRootList = null;
        WpAqglwlVO parent =null;
        TreeMenuNode treeMenuNode = new TreeMenuNode();
        wpJgzzAqglwlBO.setGmtCreatedBy(userId);
        List<WpAqglwlVO> wpAqglwlVOS = jgzzAqglwlMapper.listAll(wpJgzzAqglwlBO);
        WpAqglwlVO wpAqglwlVO = wpAqglwlVOS.stream().filter(p->p.getIsDeleted()==0).filter(p -> p.getParentId() == null||"".equals(p.getParentId())).collect(Collectors.toList()).get(0);
        BeanUtils.copyProperties(wpAqglwlVO,treeMenuNode);
        List<TreeMenuNode> stringListMap = transTree(treeMenuNode, wpAqglwlVOS);
        return stringListMap;
    }

    public List<TreeMenuNode> transTree(TreeMenuNode treeMenuNode1,List<WpAqglwlVO> wpAqglwlVOS) {
        List<TreeMenuNode> treeNodeList = new ArrayList<>();
        //转换数据,这个是前端需要的格式。
        wpAqglwlVOS.forEach(t->{
            TreeMenuNode treeMenuNode = new TreeMenuNode();
            treeMenuNode.setId(t.getId());
            treeMenuNode.setParentId(t.getParentId());
            treeMenuNode.setManageName(t.getName());
            treeMenuNode.setSortIndex(t.getSortIndex());
            treeMenuNode.setId(t.getId());
            treeMenuNode.setPrincipal(t.getPrincipal());
            treeMenuNode.setPrincipalPhone(t.getPrincipalPhone());
            treeMenuNode.setRemark(t.getRemark());
            treeMenuNode.setSafeDuty(t.getSafeDuty());
            treeNodeList.add(treeMenuNode);
        });
        //分组
        Map<String, List<TreeMenuNode>> collect = treeNodeList.stream().collect(Collectors.groupingBy(TreeMenuNode::getParentId));
        //树形结构 肯定有一个根部，我的这个根部的就是parentId.euqal("0"),而且只有一个就get（"0"）
        //TreeMenuNode treeMenuNode = collect.get("0").get(0);
        //拼接数据
        List<TreeMenuNode> treeMenuNodes = ToModel.forEach(collect, treeMenuNode1);
        return treeMenuNodes;
    }


}

TreeMenuNode

package com.hainei.common.tree.myTree;
import io.swagger.annotations.ApiModelProperty;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import javax.persistence.Column;
import javax.persistence.Id;
import java.io.Serializable;
import java.util.List;
import java.util.Map;


@Data
@AllArgsConstructor
@NoArgsConstructor
public class TreeMenuNode implements Serializable {
    @Id
    private String id;

    /**
     * 父节点id
     */
    @Column(name = "parent_id")
    @ApiModelProperty(value = "父节点id",example = "父节点id")
    private String parentId;

    /**
     * 子节点排序
     */
    @Column(name = "sort_index")
    @ApiModelProperty(value = "子节点排序",example = "子节点排序")
    private Integer sortIndex;

    /**
     * 名称
     */
    @Column(name = "manage_name")
    @ApiModelProperty(value = "名称",example = "名称")
    private String manageName;

    /**
     * 负责人
     */
    @ApiModelProperty(value = "负责人",example = "负责人")
    private String principal;

    /**
     * 负责人联系方式
     */
    @Column(name = "principal_phone")
    @ApiModelProperty(value = "负责人联系方式",example = "负责人联系方式")
    private String principalPhone;

    /**
     * 备注
     */
    @ApiModelProperty(value = "备注",example = "备注")
    private String remark;

    @ApiModelProperty(value = "安全职责",example = "安全职责")
    private String safeDuty;

//    private String name;
//    private Integer sort;
    private List<TreeMenuNode> children;
    private Boolean isAble;

    /**20180929zhw添加 树的额外属性(至少含有父节点ID:"parentId")**/
    private Map<String,Object> attributes;
}

 

每天进步一步步，坚持坚持坚持