Java 数据库查询结果的list转树

谁借莪１个温暖的怀抱￠ 2024-04-18 19:25 27阅读 0赞

package com.example.dataStructure.collectionToTree;
    
    import com.alibaba.fastjson.JSON;
    import org.springframework.util.StringUtils;
    
    import java.util.*;
    
    public class KypCodeMappingTree {
    
        Node[] heads;
    
        public KypCodeMappingTree(List<Map<String,String>> list) {
            this.heads = this.initHeads(list);
            this.treeIfy(list);
        }
    
        /**
         * 初始化头节点
         * @param list
         * @return
         */
        private Node[] initHeads(List<Map<String,String>> list){
            List<Node> headList = new ArrayList<Node>();
            if(list == null || list.isEmpty()){
                return null;
            }
            for (Map<String,String> map:list
                 ) {
                if(StringUtils.isEmpty(this.mapPreWords(map))){
                    Node node = new Node();
                    node.setKey(this.mapWords(map));
                    headList.add(node);
                }
            }
            Node[] heads = new Node[headList.size()];
            return headList.toArray(heads);
        }
    
        public String mapWords(Map map){
            return map.get("columnName")+","+map.get("valueCode");
        }
    
        public String mapPreWords(Map map){
            if(StringUtils.isEmpty(map.get("preColumnName")) || StringUtils.isEmpty(map.get("preValueCode"))){
                return null;
            }
            return map.get("preColumnName")+","+map.get("preValueCode");
        }
    
        /**
         * 树化
         * @param list
         */
        protected void treeIfy(List<Map<String,String>> list){
            // 将list转换成父(key)子(value)的map
            Map<String,List<String>> map = reverse(list);
            if(this.heads != null && heads.length>0){
                for (Node head:heads
                 ) {
                    this.addChildren(head,map);
                }
            }
        }
    
        /**
         * 添加子节点
         * @param head
         * @param map
         */
        protected void addChildren(Node head,Map<String,List<String>> map){
            if(head==null){
                return;
            }
            Queue<Node> q=new LinkedList<>();
            q.add(head);
            while (!q.isEmpty()){
                Node curr = q.poll();
                List<String> childList = map.get(curr.getKey());
                if(childList != null && !childList.isEmpty()){
                    for (String childKey:childList
                         ) {
                        Node child = new Node();
                        child.setKey(childKey);
                        curr.getChildren().add(child);
                        q.add(child);
                    }
    
                }
            }
        }
    
        /**
         * 将list转成含有父子节点层级关系的map，key代表父节点，map中的value值是list集合，代表子节点列表
         * @param list
         * @return
         */
        protected Map<String,List<String>> reverse(List<Map<String,String>> list){
            if(list == null || list.isEmpty()){
                return null;
            }
            Map<String,List<String>> map = new HashMap<>();
            for (Map<String,String> m:list
                 ) {
                if(!map.containsKey(this.mapWords(m))){
                    List<String> mapL = new ArrayList<>();
                    mapL.addAll(this.findChildren(list,m));
                    map.put(this.mapWords(m),mapL);
                }
            }
            return map;
        }
    
        /**
         * 获取节点map的value，即子节点的key的list
         * @param list
         * @param map
         * @return
         */
        public List<String> findChildren(List<Map<String,String>> list,Map<String,String> map){
            List<String> children = new ArrayList<>();
            for (Map<String,String> m:list
                 ) {
                if(this.mapWords(map).equals(this.mapPreWords(m))){
                    children.add(this.mapWords(m));
                }
            }
            return children;
        }
    
        public Node[] getHeads() {
            return heads;
        }
    
        public void setHeads(Node[] heads) {
            this.heads = heads;
        }
    
        static class Node {
            String key;
            List<Node> children = new ArrayList<>();
    
            public String getKey() {
                return key;
            }
    
            public void setKey(String key) {
                this.key = key;
            }
    
            public List<Node> getChildren() {
                return children;
            }
    
            public void setChildren(List<Node> children) {
                this.children = children;
            }
        }
    
        public static void main(String[] args) {
            List<Map<String,String>> list = initData();
            KypCodeMappingTree tree = new KypCodeMappingTree(list);
            System.out.println(JSON.toJSONString(tree));
        }
    
        public static List<Map<String,String>> initData(){
            Map k1 = (new KypCodeMapping("kyp_level1", "B2C", null, null)).objectToMap();
            Map k3 = (new KypCodeMapping("kyp_level2", "B2C固收类", "kyp_level1", "B2C")).objectToMap();
            Map k4 = (new KypCodeMapping("kyp_level2", "B2C宝宝类", "kyp_level1", "B2C")).objectToMap();
            Map k5 = (new KypCodeMapping("kyp_level2", "B2C跨境类", "kyp_level1", "B2C")).objectToMap();
            Map k6 = (new KypCodeMapping("kyp_level1", "爱理财", null, null)).objectToMap();
            Map k14 = (new KypCodeMapping("kyp_level2", "爱理财", "kyp_level1", "爱理财")).objectToMap();
            Map k15 = (new KypCodeMapping("kyp_level3", "爱理财", "kyp_level2", "爱理财")).objectToMap();
            Map k16 = (new KypCodeMapping("kyp_level4", "爱理财", "kyp_level3", "爱理财")).objectToMap();
            Map k7 = (new KypCodeMapping("kyp_level1", "投股票", null, null)).objectToMap();
            Map k9 = (new KypCodeMapping("kyp_level2", "爱理财1号", "kyp_level1", "爱理财")).objectToMap();
            Map k2 = (new KypCodeMapping("kyp_level2", "爱理财2号", "kyp_level1", "爱理财")).objectToMap();
            Map k8 = (new KypCodeMapping("kyp_level2", "爱理财3号", "kyp_level1", "爱理财")).objectToMap();
            Map k10 = (new KypCodeMapping("kyp_level3", "爱理财1号1类", "kyp_level2", "爱理财1号")).objectToMap();
            Map k11 = (new KypCodeMapping("kyp_level3", "爱理财1号2类", "kyp_level2", "爱理财1号")).objectToMap();
            Map k12 = (new KypCodeMapping("kyp_level4", "爱理财1号1类a", "kyp_level3", "爱理财1号1类")).objectToMap();
            Map k13 = (new KypCodeMapping("kyp_level4", "爱理财1号1类b", "kyp_level3", "爱理财1号1类")).objectToMap();
            List<Map<String,String>> list = new ArrayList<>();
            list.add(k1);list.add(k2);list.add(k3);list.add(k4);list.add(k5);list.add(k6);list.add(k7);
            list.add(k8);list.add(k9);list.add(k10);list.add(k11);list.add(k12);list.add(k13);list.add(k14);
            list.add(k15);list.add(k16);
            return list;
        }
    }

结果：\{"heads":\[\{"children":\[\{"children":\[\],"key":"kyp\_level2,B2C固收类"\},\{"children":\[\],"key":"kyp\_level2,B2C宝宝类"\},\{"children":\[\],"key":"kyp\_level2,B2C跨境类"\}\],"key":"kyp\_level1,B2C"\},\{"children":\[\{"children":\[\],"key":"kyp\_level2,爱理财2号"\},\{"children":\[\],"key":"kyp\_level2,爱理财3号"\},\{"children":\[\{"children":\[\{"children":\[\],"key":"kyp\_level4,爱理财1号1类a"\},\{"children":\[\],"key":"kyp\_level4,爱理财1号1类b"\}\],"key":"kyp\_level3,爱理财1号1类"\},\{"children":\[\],"key":"kyp\_level3,爱理财1号2类"\}\],"key":"kyp\_level2,爱理财1号"\},\{"children":\[\{"children":\[\{"children":\[\],"key":"kyp\_level4,爱理财"\}\],"key":"kyp\_level3,爱理财"\}\],"key":"kyp\_level2,爱理财"\}\],"key":"kyp\_level1,爱理财"\},\{"children":\[\],"key":"kyp\_level1,投股票"\}\]\}

\{  
    "heads":\[  
        \{  
            "children":\[  
                \{  
                    "children":\[  
  
                    \],  
                    "key":"kyp\_level2,B2C固收类"  
                \},  
                \{  
                    "children":\[  
  
                    \],  
                    "key":"kyp\_level2,B2C宝宝类"  
                \},  
                \{  
                    "children":\[  
  
                    \],  
                    "key":"kyp\_level2,B2C跨境类"  
                \}  
            \],  
            "key":"kyp\_level1,B2C"  
        \},  
        \{  
            "children":\[  
                \{  
                    "children":\[  
  
                    \],  
                    "key":"kyp\_level2,爱理财2号"  
                \},  
                \{  
                    "children":\[  
  
                    \],  
                    "key":"kyp\_level2,爱理财3号"  
                \},  
                \{  
                    "children":\[  
                        \{  
                            "children":\[  
                                \{  
                                    "children":\[  
  
                                    \],  
                                    "key":"kyp\_level4,爱理财1号1类a"  
                                \},  
                                \{  
                                    "children":\[  
  
                                    \],  
                                    "key":"kyp\_level4,爱理财1号1类b"  
                                \}  
                            \],  
                            "key":"kyp\_level3,爱理财1号1类"  
                        \},  
                        \{  
                            "children":\[  
  
                            \],  
                            "key":"kyp\_level3,爱理财1号2类"  
                        \}  
                    \],  
                    "key":"kyp\_level2,爱理财1号"  
                \},  
                \{  
                    "children":\[  
                        \{  
                            "children":\[  
                                \{  
                                    "children":\[  
  
                                    \],  
                                    "key":"kyp\_level4,爱理财"  
                                \}  
                            \],  
                            "key":"kyp\_level3,爱理财"  
                        \}  
                    \],  
                    "key":"kyp\_level2,爱理财"  
                \}  
            \],  
            "key":"kyp\_level1,爱理财"  
        \},  
        \{  
            "children":\[  
  
            \],  
            "key":"kyp\_level1,投股票"  
        \}  
    \]  
\}