java 处理mysql获取树形的数据带级别和子集数量

r囧r小猫 2024-03-17 20:58 9阅读 0赞

### 要求： ###

[获取数据生成树形数据][Link 1]后，要求返回返回层级（level）和子集(childCount)的个数，便于前端处理。

### 处理： ###

1，在遍历的时候，进行处理。 （适合内部调用）

2，在生产树形后，再遍历处理。（适合外部调用，获取的数据已经是树形了，不好改引用的接口）

#### 添加属性： ####

import java.util.ArrayList;
    import java.util.List;
    
    public class TreeModel {
        private String name;
        private String code;
        private String parentCode;
        private int level;
        private int childCount;
        private List<TreeModel> children;
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public String getCode() {
            return code;
        }
    
        public void setCode(String code) {
            this.code = code;
        }
    
        public String getParentCode() {
            return parentCode;
        }
    
        public void setParentCode(String parentCode) {
            this.parentCode = parentCode;
        }
    
        public List<TreeModel> getChildren() {
            return children;
        }
    
        public int getLevel() {
            return level;
        }
    
        public void setLevel(int level) {
            this.level = level;
        }
    
        public int getChildCount() {
            return childCount;
        }
    
        public void setChildCount(int childCount) {
            this.childCount = childCount;
        }
    
        public void setChildren(List<TreeModel> children) {
            if (children.size() == 0) {
                this.children = new ArrayList<>();
            } else {
                this.children = children;
    
            }
        }
    
        @Override
        public String toString() {
            return "{"
                    + "\"name\":\""
                    + name + '\"'
                    + ",\"code\":\""
                    + code + '\"'
                    + ",\"parentCode\":\""
                    + parentCode + '\"'
                    + ",\"level\":"
                    + level
                    + ",\"childCount\":"
                    + childCount
                    + ",\"children\":"
                    + children
                    + "}";
        }
    }

#### 遍历的时候添加 ####

import com.alibaba.fastjson.JSON;
    import com.alibaba.fastjson.JSONArray;
    import com.alibaba.fastjson.JSONObject;
    import com.yan.web.util.treeNode.listMap1.TreeModel;
    import org.apache.commons.collections4.CollectionUtils;
    import org.apache.commons.collections4.ListUtils;
    import org.apache.commons.lang3.StringUtils;
    
    import java.util.*;
    import java.util.stream.Collectors;
    
    public class TreeModelWithLevel {
    
        public static void main(String[] args){
            List<TreeModel> areaList = initData();
            // 构建树形
            List<TreeModel> treeModels = parseTreeModel(areaList);
            System.out.println("result: "+ JSON.toJSONString(treeModels));
        }
    
        private static List<TreeModel> parseTreeModel(List<TreeModel> treeModels) {
            if (CollectionUtils.isEmpty(treeModels)) {
                return Collections.emptyList();
            }
            Map<String, List<TreeModel>> map = new HashMap<>();
            treeModels.forEach(x -> {
                String parentCode = x.getParentCode();
                if (StringUtils.isBlank(parentCode)) {
                    parentCode = "-1";
                }
                // 如果 parentCode 没有值，生成空数组，
                List<TreeModel> list = map.computeIfAbsent(parentCode, k -> new ArrayList<>());
                // 如果有值，就把值取出来，相同的parentCode 放到一起
                list.add(x);
            });
            // 从-1开始遍历
            List<TreeModel> result = map.getOrDefault("-1", new ArrayList<>());
            parseChildrenTreeModel(0, map, result);
            return result;
        }
    
        private static void parseChildrenTreeModel(int level, Map<String, List<TreeModel>> map, List<TreeModel> treeModels) {
            level++;
            for (TreeModel x : treeModels) {
                List<TreeModel> orDefault = map.getOrDefault(x.getCode(), new ArrayList<>());
                x.setChildren(orDefault);
                x.setLevel(level);
                x.setChildCount(orDefault.size());
                if (!CollectionUtils.isEmpty(x.getChildren())) {
                    parseChildrenTreeModel(level, map, x.getChildren());
                }
            }
        }
    
        private static List<TreeModel> initData(){
            String areaInfo = "[{\n" +
                    "\t\t\"code\": 59,\n" +
                    "\t\t\"parentCode\": -1,\n" +
                    "\t\t\"name\": \"福建\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 591,\n" +
                    "\t\t\"parentCode\": 59,\n" +
                    "\t\t\"name\": \"福州\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59101,\n" +
                    "\t\t\"parentCode\": 591,\n" +
                    "\t\t\"name\": \"鼓楼区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59195,\n" +
                    "\t\t\"parentCode\": 591,\n" +
                    "\t\t\"name\": \"晋安区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59196,\n" +
                    "\t\t\"parentCode\": 591,\n" +
                    "\t\t\"name\": \"马尾区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59197,\n" +
                    "\t\t\"parentCode\": 591,\n" +
                    "\t\t\"name\": \"台江区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59198,\n" +
                    "\t\t\"parentCode\": 591,\n" +
                    "\t\t\"name\": \"金山区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 592,\n" +
                    "\t\t\"parentCode\": 59,\n" +
                    "\t\t\"name\": \"厦门\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59201,\n" +
                    "\t\t\"parentCode\": 592,\n" +
                    "\t\t\"name\": \"思明区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59202,\n" +
                    "\t\t\"parentCode\": 592,\n" +
                    "\t\t\"name\": \"同安\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59203,\n" +
                    "\t\t\"parentCode\": 592,\n" +
                    "\t\t\"name\": \"杏林\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59204,\n" +
                    "\t\t\"parentCode\": 592,\n" +
                    "\t\t\"name\": \"海沧区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59205,\n" +
                    "\t\t\"parentCode\": 592,\n" +
                    "\t\t\"name\": \"同安区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59206,\n" +
                    "\t\t\"parentCode\": 592,\n" +
                    "\t\t\"name\": \"翔安区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 593,\n" +
                    "\t\t\"parentCode\": 59,\n" +
                    "\t\t\"name\": \"宁德\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59301,\n" +
                    "\t\t\"parentCode\": 593,\n" +
                    "\t\t\"name\": \"宁德\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59302,\n" +
                    "\t\t\"parentCode\": 593,\n" +
                    "\t\t\"name\": \"古田\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59303,\n" +
                    "\t\t\"parentCode\": 593,\n" +
                    "\t\t\"name\": \"屏南\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59304,\n" +
                    "\t\t\"parentCode\": 593,\n" +
                    "\t\t\"name\": \"寿宁\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59305,\n" +
                    "\t\t\"parentCode\": 593,\n" +
                    "\t\t\"name\": \"周宁\"\n" +
                    "\t}]";
            JSONArray areaArr = JSONArray.parseArray(areaInfo);
            return ListUtils.emptyIfNull(areaArr).stream().map(e -> (JSONObject) e)
                    .map(e -> JSONObject.parseObject(e.toString(), TreeModel.class)).collect(Collectors.toList());
        }
    }

#### 遍历树形数据添加 ####

import com.alibaba.fastjson.JSON;
    import com.alibaba.fastjson.JSONArray;
    import com.alibaba.fastjson.JSONObject;
    import com.yan.web.util.treeNode.listMap1.TreeModel;
    import org.apache.commons.collections4.CollectionUtils;
    import org.apache.commons.collections4.ListUtils;
    import org.apache.commons.lang3.StringUtils;
    
    import java.util.*;
    import java.util.stream.Collectors;
    
    public class TreeModelAddLevel {
    
        public static void main(String[] args){
            List<TreeModel> areaList = initData();
            // 构建树形
            List<TreeModel> treeModels = parseTreeModel(areaList);
            System.out.println("result: "+ JSON.toJSONString(treeModels));
            addLevel(0, treeModels);
            System.out.println("result2: "+ JSON.toJSONString(treeModels));
    
        }
    
        private static void addLevel(int level, List<TreeModel> treeModels){
            level++;
            for (TreeModel treeModel : ListUtils.emptyIfNull(treeModels)) {
                treeModel.setLevel(level);
                List<TreeModel> children = treeModel.getChildren();
                treeModel.setChildCount(children.size());
                if(CollectionUtils.isNotEmpty(children)){
                    addLevel(level, children);
                }
            }
        }
    
        private static List<TreeModel> parseTreeModel(List<TreeModel> treeModels) {
            if (CollectionUtils.isEmpty(treeModels)) {
                return Collections.emptyList();
            }
            Map<String, List<TreeModel>> map = new HashMap<>();
            treeModels.forEach(x -> {
                String parentCode = x.getParentCode();
                if (StringUtils.isBlank(parentCode)) {
                    parentCode = "-1";
                }
                // 如果 parentCode 没有值，生成空数组，
                List<TreeModel> list = map.computeIfAbsent(parentCode, k -> new ArrayList<>());
                // 如果有值，就把值取出来，相同的parentCode 放到一起
                list.add(x);
            });
            // 从-1开始遍历
            List<TreeModel> result = map.getOrDefault("-1", new ArrayList<>());
            parseChildrenTreeModel(map, result);
            return result;
        }
    
        private static void parseChildrenTreeModel(Map<String, List<TreeModel>> map, List<TreeModel> treeModels) {
            treeModels.forEach(x -> {
                x.setChildren(map.getOrDefault(x.getCode(), new ArrayList<>()));
                if (!CollectionUtils.isEmpty(x.getChildren())) {
                    parseChildrenTreeModel(map, x.getChildren());
                }
            });
        }
    
        private static List<TreeModel> initData(){
            String areaInfo = "[{\n" +
                    "\t\t\"code\": 59,\n" +
                    "\t\t\"parentCode\": -1,\n" +
                    "\t\t\"name\": \"福建\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 591,\n" +
                    "\t\t\"parentCode\": 59,\n" +
                    "\t\t\"name\": \"福州\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59101,\n" +
                    "\t\t\"parentCode\": 591,\n" +
                    "\t\t\"name\": \"鼓楼区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59195,\n" +
                    "\t\t\"parentCode\": 591,\n" +
                    "\t\t\"name\": \"晋安区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59196,\n" +
                    "\t\t\"parentCode\": 591,\n" +
                    "\t\t\"name\": \"马尾区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59197,\n" +
                    "\t\t\"parentCode\": 591,\n" +
                    "\t\t\"name\": \"台江区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59198,\n" +
                    "\t\t\"parentCode\": 591,\n" +
                    "\t\t\"name\": \"金山区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 592,\n" +
                    "\t\t\"parentCode\": 59,\n" +
                    "\t\t\"name\": \"厦门\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59201,\n" +
                    "\t\t\"parentCode\": 592,\n" +
                    "\t\t\"name\": \"思明区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59202,\n" +
                    "\t\t\"parentCode\": 592,\n" +
                    "\t\t\"name\": \"同安\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59203,\n" +
                    "\t\t\"parentCode\": 592,\n" +
                    "\t\t\"name\": \"杏林\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59204,\n" +
                    "\t\t\"parentCode\": 592,\n" +
                    "\t\t\"name\": \"海沧区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59205,\n" +
                    "\t\t\"parentCode\": 592,\n" +
                    "\t\t\"name\": \"同安区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59206,\n" +
                    "\t\t\"parentCode\": 592,\n" +
                    "\t\t\"name\": \"翔安区\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 593,\n" +
                    "\t\t\"parentCode\": 59,\n" +
                    "\t\t\"name\": \"宁德\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59301,\n" +
                    "\t\t\"parentCode\": 593,\n" +
                    "\t\t\"name\": \"宁德\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59302,\n" +
                    "\t\t\"parentCode\": 593,\n" +
                    "\t\t\"name\": \"古田\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59303,\n" +
                    "\t\t\"parentCode\": 593,\n" +
                    "\t\t\"name\": \"屏南\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59304,\n" +
                    "\t\t\"parentCode\": 593,\n" +
                    "\t\t\"name\": \"寿宁\"\n" +
                    "\t},\n" +
                    "\t{\n" +
                    "\t\t\"code\": 59305,\n" +
                    "\t\t\"parentCode\": 593,\n" +
                    "\t\t\"name\": \"周宁\"\n" +
                    "\t}]";
            JSONArray areaArr = JSONArray.parseArray(areaInfo);
            return ListUtils.emptyIfNull(areaArr).stream().map(e -> (JSONObject) e)
                    .map(e -> JSONObject.parseObject(e.toString(), TreeModel.class)).collect(Collectors.toList());
        }
    
    }

### 总结： ###

在生成树形数据的时候，要添加层级和子集个数，可以

1，在遍历的时候，进行处理。 （适合内部调用）

2，在生产树形后，再遍历处理。（适合外部调用，获取的数据已经是树形了，不好改引用的接口）

[Link 1]: https://blog.csdn.net/qq_35461948/article/details/112665917