java递归

实体类：

public class Entry {
    private Integer id;
    private String fullName;
    private String levelName;
    private Integer level;

    public Entry(Integer id, String fullName, String levelName, Integer level) {
        this.id = id;
        this.fullName = fullName;
        this.levelName = levelName;
        this.level = level;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getFullName() {
        return fullName;
    }

    public void setFullName(String fullName) {
        this.fullName = fullName;
    }

    public String getLevelName() {
        return levelName;
    }

    public void setLevelName(String levelName) {
        this.levelName = levelName;
    }

    public Integer getLevel() {
        return level;
    }

    public void setLevel(Integer level) {
        this.level = level;
    }
}

 Main主方法：

import com.alibaba.fastjson.JSONObject;

import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class Main {
    public static void main(String[] args) {
        Map> map = new HashMap<>();
        String firstKey = null;
        for (Entry test : testList()) {
            if (test.getLevel() == 1){
                firstKey = test.getLevelName();
                System.out.println(firstKey+"===========");
                List list = new ArrayList<>();
                map.put(test.getLevelName(),list);
            }else {
                String key = test.getLevelName().substring(0,test.getLevelName().lastIndexOf('.'));
                if (map.containsKey(key)){
                    map.get(key).add(test);
                }else {
                    List list = new ArrayList<>();
                    list.add(test);
                    map.put(key,list);
                }
            }
        }
        Map result = new HashMap<>();
        result.put(firstKey, cycle(map,firstKey));
        System.out.println(JSONObject.toJSONString(result));
    }

    private static List cycle(Map> map, String key){
        if (map.containsKey(key)){
            List list = new ArrayList();
            map.get(key).forEach(entry->{
                List testResult = cycle(map, entry.getLevelName());
                if (testResult == null){
                    list.add(entry.getFullName());
                }else {
                    Map map1 = new HashMap();
                    map1.put(entry.getFullName(),testResult);
                    list.add(map1);
                }
            });
            return list;
        }
        return null;
    }

    static private List testList(){
        List list = new ArrayList<>();
        list.add(new Entry(1, "1_xxx", "1", 1));
        list.add(new Entry(2, "1.1_xxx", "1.1", 2));
        list.add(new Entry(3, "1.2_xxx", "1.2", 2));
        list.add(new Entry(4, "1.3_xxx", "1.3", 2));
        list.add(new Entry(5, "1.1.1_xxx", "1.1.1", 3));
        list.add(new Entry(6, "1.1.2_xx", "1.1.2", 3));
        list.add(new Entry(7, "1.2.1_xxx", "1.2.1", 3));
        list.add(new Entry(8, "1.3.1_xxx", "1.3.1", 3));
        list.add(new Entry(9, "1.3.2_xxx", "1.3.2", 3));
        list.add(new Entry(10, "1.1.1.1_xxx", "1.1.1.1", 4));
        list.add(new Entry(11, "2_xxx", "2", 1));
        list.add(new Entry(12, "2.1_xxx", "2.1", 2));
        list.add(new Entry(13, "2.2_xxx", "2.2", 2));
        list.add(new Entry(14, "2.3_xxx", "2.3", 2));
        list.add(new Entry(15, "2.1.1_xxx", "2.1.1", 3));
        list.add(new Entry(16, "2.1.2_xx", "2.1.2", 3));
        list.add(new Entry(17, "2.2.1_xxx", "2.2.1", 3));
        list.add(new Entry(18, "2.3.1_xxx", "2.3.1", 3));
        list.add(new Entry(19, "2.3.2_xxx", "2.3.2", 3));
        list.add(new Entry(20, "2.1.1.1_xxx", "2.1.1.1", 4));
        return list;
    }
}