个人技术分享

1.TreeNode类

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.util.List;

@Data
@NoArgsConstructor
@AllArgsConstructor
public class TreeNode {
    Integer id;
    String value;
    /** 子节点信息 */
    List<TreeNode> childrens;
    /** 父节点信息,根节点的父Id是0 */
    Integer parentId;

    public TreeNode(Integer id, String value, Integer parentId) {
        this.id = id;
        this.value = value;
        this.parentId = parentId;
    }
}

2.测试类

import cn.hutool.json.JSON;
import cn.hutool.json.JSONUtil;
import java.util.Arrays;
import java.util.List;
import java.util.Objects;
import java.util.stream.Collectors;

public class TreeNodeAssemble {
    public static void main(String[] args) {
        List<TreeNode> list = createList();
        //根据parentId=0获取根节点
        List<TreeNode> collect = list.stream().filter(m -> m.parentId == 0).map(
                (x) -> {x.childrens = getChildren(x, list);
                        return x;
                        }
        ).collect(Collectors.toList());
        JSON json = JSONUtil.parse(collect);
        System.out.println(json);
    }

    /**
     * 递归查询子节点
     * @param root
     * @param listAll
     * @return
     */
    private static List<TreeNode> getChildren(TreeNode root, List<TreeNode> listAll) {
        List<TreeNode> children = listAll.stream().filter(x-> Objects.equals(x.parentId, root.id))
                .map(y->{
                    y.childrens = getChildren(y,listAll);
                    return y;})
                .collect(Collectors.toList());
        return children;
    }

    private static List<TreeNode> createList() {
        List<TreeNode> list = Arrays.asList(
                new TreeNode(1,"跟节点",0),
                new TreeNode(2,"韦德-狗1",1),
                new TreeNode(3,"韦德-猪1",1),
                new TreeNode(4,"韦德-狗1-2",2),
                new TreeNode(5,"韦德-狗1-3",2),
                new TreeNode(6,"韦德-猪1-2",3),
                new TreeNode(7,"韦德-狗1-2-4",4),
                new TreeNode(8,"韦德-狗1-2-5",4),
                new TreeNode(9,"韦德-猪2-3",6),
                new TreeNode(10,"韦德-猪2-4",6)
        );
        return list;
    }

}

3.结果