最近的工作有遇到此需求,如權(quán)限樹狀結(jié)構(gòu)。因?yàn)閿?shù)據(jù)庫(kù)采用的MySQL，其在語義層面對(duì)于樹狀結(jié)構(gòu)的查詢支持偏弱早芭。查詢了諸多資料，個(gè)人感覺靠譜的不多遂萌生了自己寫一個(gè)的想法诅蝶。話不多說啊退个，直接貼代碼：

package tree;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

import org.apache.commons.lang3.builder.EqualsBuilder;

import com.alibaba.fastjson.JSON;

import lombok.Getter;
import lombok.Setter;
import lombok.ToString;

/**
 * 樹形結(jié)構(gòu)解析
 * 
 * @author gewx
 **/
public final class Tree {

    /**
     * 解析數(shù)據(jù)結(jié)構(gòu)
     * 
     * @author gewx
     * @param nodeList 數(shù)據(jù)節(jié)點(diǎn)集合
     * @return 解析完成后的樹狀結(jié)果
     **/
    public static List<Node> parse(List<Node> nodeList) {
        List<Node> resultList = new ArrayList<>(64);
        nodeList.stream().filter(val -> !hasChild(nodeList, val.getMenuId())).collect(Collectors.toList())
                .forEach(val -> {
                    reverseRecursion(val, nodeList, resultList);
                });

        Set<Node> set = new HashSet<>(32);
        set.addAll(resultList);

        resultList.clear();
        set.stream().forEach(val -> {
            resultList.add(val);
            recursion(val, nodeList);
        });

        return resultList;
    }

    /**
     * 取出某個(gè)節(jié)點(diǎn)直至末尾葉子節(jié)點(diǎn)的數(shù)據(jù)
     * 
     * @author gewx
     * @param node     葉子節(jié)點(diǎn)
     * @param nodeList 數(shù)據(jù)節(jié)點(diǎn)集合
     * @return 解析完成后的樹狀結(jié)果
     **/
    public static void getNodeJson(Node node, List<Node> nodeList) {
        recursion(node, nodeList);
    }

    /**
     * 倒序遞歸檢索所有父節(jié)點(diǎn),由下往上直到所有根節(jié)點(diǎn)
     * 
     * @author gewx
     * @param node       末尾葉子節(jié)點(diǎn)
     * @param nodeList   數(shù)據(jù)節(jié)點(diǎn)集合
     * @param resultList 根節(jié)點(diǎn)集合
     * @return void
     **/
    private static void reverseRecursion(Node node, List<Node> nodeList, List<Node> resultList) {
        List<Node> parentNodeList = nodeList.stream().filter(val -> val.getMenuId().equals(node.getParentId()))
                .collect(Collectors.toList());
        if (parentNodeList.size() != 0) {
            Node parentNode = parentNodeList.get(0);
            reverseRecursion(parentNode, nodeList, resultList);
        } else {
            resultList.add(node);
        }
    }

    /**
     * 遞歸檢索所有子節(jié)點(diǎn)
     * 
     * @author gewx
     * @param node     根節(jié)點(diǎn)
     * @param nodeList 數(shù)據(jù)節(jié)點(diǎn)集合
     * @return void
     **/
    private static void recursion(Node node, List<Node> nodeList) {
        List<Node> childNodeList = nodeList.stream().filter(val -> val.getParentId().equals(node.getMenuId()))
                .collect(Collectors.toList());
        if (childNodeList.size() != 0) {
            node.setChildren(childNodeList);
            childNodeList.stream().forEach(val -> {
                recursion(val, nodeList);
            });
        }
    }

    /**
     * 是否還存在父級(jí)元素,找出末尾葉子節(jié)點(diǎn)
     * 
     * @author gewx
     * 
     * @param node   葉子節(jié)點(diǎn)
     * @param menuId 節(jié)點(diǎn)標(biāo)記
     * @return boolean true 存在, false 不存在
     **/
    private static boolean hasChild(List<Node> node, String menuId) {
        return node.stream().anyMatch(val -> val.getParentId().equals(menuId));
    }

    /**
     * 葉子節(jié)點(diǎn)數(shù)據(jù)結(jié)構(gòu),可與庫(kù)表做一一映射僅需要保持menuId與parentId映射關(guān)系即可
     **/
    @Getter
    @Setter
    @ToString
    public static class Node {

        /**
         * 菜單Id
         **/
        private String menuId;

        /**
         * 菜單名稱
         **/
        private String menuName;

        /**
         * 菜單類型
         **/
        private String menuType;

        /**
         * 菜單編碼
         **/
        private String menuCode;

        /**
         * 菜單URL
         **/
        private String url;

        /**
         * 菜單父級(jí)Id
         **/
        public String parentId;

        /**
         * 排序
         **/
        private Integer sortNum;

        /**
         * 子菜單
         **/
        private List<Node> children = new ArrayList<>();

        public Node(String menuId, String menuName, String menuType, String menuCode, String url, String parentId,
                Integer sortNum) {
            this.menuId = menuId;
            this.menuName = menuName;
            this.menuType = menuType;
            this.menuCode = menuCode;
            this.url = url;
            this.parentId = parentId;
            this.sortNum = sortNum;
        }

        @Override
        public final boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }

            Node otherObject = (Node) obj;
            if (getClass() != otherObject.getClass()) {
                return false;
            }

            EqualsBuilder builder = new EqualsBuilder();
            builder.append(this.menuId, otherObject.getMenuId());
            return builder.isEquals();
        }

        @Override
        public final int hashCode() {
            return this.menuId.hashCode() * 31;
        }
    }

    public static void main(String[] args) {
        List<Node> array = new ArrayList<>();
        array.add(new Tree.Node("CODE_00", "用戶管理", "M", "0101", "#", "0", 0));
        array.add(new Tree.Node("CODE_01", "管理界面", "M", "0102", "#", "0", 0));
        array.add(new Tree.Node("CODE_02", "權(quán)限管理", "C", "010101", "http://www.baidu.com", "CODE_00", 0));
        array.add(new Tree.Node("CODE_03", "內(nèi)部管理", "C", "010201", "http://www.baidu.com", "CODE_01", 0));

        array.add(new Tree.Node("CODE_04", "內(nèi)部用戶權(quán)限", "C", "010201", "http://www.baidu.com", "CODE_02", 0));
        array.add(new Tree.Node("CODE_05", "外部用戶權(quán)限", "C", "010201", "http://www.baidu.com", "CODE_02", 0));
        array.add(new Tree.Node("CODE_06", "子權(quán)限", "C", "010201", "http://www.baidu.com", "CODE_04", 0));
        array.add(new Tree.Node("CODE_07", "子系統(tǒng)內(nèi)部管理", "C", "010201", "http://www.baidu.com", "CODE_03", 0));

        List<Node> list = Tree.parse(array);
        String val = JSON.toJSONString(list);
        System.out.println(val);

        // 取出當(dāng)下節(jié)點(diǎn)下所有數(shù)據(jù)
        Node node = new Tree.Node("CODE_01x", "系統(tǒng)管理員", "M", "0101", "#", "0", 0);
        Tree.getNodeJson(node, array);
        System.out.println(JSON.toJSONString(node));
    }
}

解析結(jié)果:

[
    {
        "children": [
            {
                "children": [
                    {
                        "children": [],
                        "menuCode": "010201",
                        "menuId": "CODE_07",
                        "menuName": "子系統(tǒng)內(nèi)部管理",
                        "menuType": "C",
                        "parentId": "CODE_03",
                        "sortNum": 0,
                        "url": "http://www.baidu.com"
                    }
                ],
                "menuCode": "010201",
                "menuId": "CODE_03",
                "menuName": "內(nèi)部管理",
                "menuType": "C",
                "parentId": "CODE_01",
                "sortNum": 0,
                "url": "http://www.baidu.com"
            }
        ],
        "menuCode": "0102",
        "menuId": "CODE_01",
        "menuName": "管理界面",
        "menuType": "M",
        "parentId": "0",
        "sortNum": 0,
        "url": "#"
    },
    {
        "children": [
            {
                "children": [
                    {
                        "children": [
                            {
                                "children": [],
                                "menuCode": "010201",
                                "menuId": "CODE_06",
                                "menuName": "子權(quán)限",
                                "menuType": "C",
                                "parentId": "CODE_04",
                                "sortNum": 0,
                                "url": "http://www.baidu.com"
                            }
                        ],
                        "menuCode": "010201",
                        "menuId": "CODE_04",
                        "menuName": "內(nèi)部用戶權(quán)限",
                        "menuType": "C",
                        "parentId": "CODE_02",
                        "sortNum": 0,
                        "url": "http://www.baidu.com"
                    },
                    {
                        "children": [],
                        "menuCode": "010201",
                        "menuId": "CODE_05",
                        "menuName": "外部用戶權(quán)限",
                        "menuType": "C",
                        "parentId": "CODE_02",
                        "sortNum": 0,
                        "url": "http://www.baidu.com"
                    }
                ],
                "menuCode": "010101",
                "menuId": "CODE_02",
                "menuName": "權(quán)限管理",
                "menuType": "C",
                "parentId": "CODE_00",
                "sortNum": 0,
                "url": "http://www.baidu.com"
            }
        ],
        "menuCode": "0101",
        "menuId": "CODE_00",
        "menuName": "用戶管理",
        "menuType": "M",
        "parentId": "0",
        "sortNum": 0,
        "url": "#"
    }
]

支持無限級(jí)聯(lián)樹，僅需要保證數(shù)據(jù)結(jié)構(gòu)中menuId與parentId需要存在級(jí)聯(lián)關(guān)系即可调炬。個(gè)人簡(jiǎn)單測(cè)試過语盈，小伙伴有需要可以再度驗(yàn)證下。