目录

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- 
方法说明
- 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
     
      > data = new ArrayList<>();   Map
      
        map = new HashMap<>();   map.put("id",1);   map.put("pid",0);   map.put("name","甘肃省");   data.add(map);   Map
       
         map2 = new HashMap<>();   map2.put("id",2);   map2.put("pid",1);   map2.put("name","天水市");   data.add(map2);   Map
        
          map3 = new HashMap<>();   map3.put("id",3);   map3.put("pid",2);   map3.put("name","秦州区");   data.add(map3);   Map
         
           map4 = new HashMap<>(); map4.put("id",4); map4.put("pid",0); map4.put("name","北京市"); data.add(map4); Map
          
            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@NoArgsConstructorpublic 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@NoArgsConstructorpublic class TreeMenuNode implements Serializable {    private String id;    private String parentId;    private String name;    private Integer sort;    private List
    
      children;    private Boolean isAble;    /**20180929zhw添加 树的额外属性(至少含有父节点ID:"parentId")**/    private Map
     
       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
    
     > collect, TreeMenuNode treeMenuNode) {        List
     
       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
      
        zhFields = new ArrayList<>();        List
       
         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
        
         > 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);    }}