java 处理mysql获取树形的数据 带级别和子集数量

要求：

获取数据生成树形数据后，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 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 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 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 areaList = initData();
        // 构建树形
        List treeModels = parseTreeModel(areaList);
        System.out.println("result: "+ JSON.toJSONString(treeModels));
    }

    private static List parseTreeModel(List treeModels) {
        if (CollectionUtils.isEmpty(treeModels)) {
            return Collections.emptyList();
        }
        Map> 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 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 result = map.getOrDefault("-1", new ArrayList<>());
        parseChildrenTreeModel(0, map, result);
        return result;
    }

    private static void parseChildrenTreeModel(int level, Map> map, List treeModels) {
        level++;
        for (TreeModel x : treeModels) {
            List 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 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 areaList = initData();
        // 构建树形
        List 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 treeModels){
        level++;
        for (TreeModel treeModel : ListUtils.emptyIfNull(treeModels)) {
            treeModel.setLevel(level);
            List children = treeModel.getChildren();
            treeModel.setChildCount(children.size());
            if(CollectionUtils.isNotEmpty(children)){
                addLevel(level, children);
            }
        }
    }

    private static List parseTreeModel(List treeModels) {
        if (CollectionUtils.isEmpty(treeModels)) {
            return Collections.emptyList();
        }
        Map> 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 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 result = map.getOrDefault("-1", new ArrayList<>());
        parseChildrenTreeModel(map, result);
        return result;
    }

    private static void parseChildrenTreeModel(Map> map, List treeModels) {
        treeModels.forEach(x -> {
            x.setChildren(map.getOrDefault(x.getCode(), new ArrayList<>()));
            if (!CollectionUtils.isEmpty(x.getChildren())) {
                parseChildrenTreeModel(map, x.getChildren());
            }
        });
    }

    private static List 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）