通过序列号生成树形结构数据、代码实现

通过下面的序列号生成有层级关系的树形结构：

代码实现

import com.alibaba.fastjson.JSON;
import lombok.Data;
import org.apache.commons.collections4.CollectionUtils;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

@Data
public class TreeNode {

    String id;

    String parentId;

    List treeNodeList;

    public static void main(String[] args) {
        List data = new ArrayList<>();
        data.add("1");
        data.add("1.1");
        data.add("1.2");
        data.add("1.3");
        data.add("1.4");
        data.add("1.1.1");
        data.add("1.2.1");
        data.add("1.3.1");
        data.add("1.3.1");

        data.add("2");
        data.add("2.1");
        data.add("2.2");
        data.add("2.3");
        data.add("2.4");

        List tree = new ArrayList<>();

        //过滤根节点
        List list = data.stream().filter(value -> !value.contains(".")).collect(Collectors.toList());

        for (String id : list) {
            TreeNode treeNode = new TreeNode();
            treeNode.setId(id);
            treeNode.setParentId("0");

            List tempChild = list.stream()
                    .filter(value -> value.split("\.")[0].equals(id))
                    .collect(Collectors.toList());

            forTree(tempChild, treeNode);

            tree.add(treeNode);
        }

        System.out.println(JSON.toJSONString(tree));
    }

    static void forTree(List data, TreeNode treeNode) {
        String id = treeNode.getId();

        List child = new ArrayList<>();

        for (String datum : data) {
            add(datum, id, child);
        }

        //无后代退出
        if (CollectionUtils.isEmpty(child)) {
            return;
        }

        treeNode.setTreeNodeList(child);

        for (TreeNode node : child) {
            forTree(data, node);
        }
    }

    static void add(String id, String parentId, List child) {

        int length = id.split("\.").length;
        StringBuilder stringBuilder = new StringBuilder();
        for (int i = 0; i <= length - 2; i++) {
            stringBuilder.append(id.split("\.")[i]);
        }

        StringBuilder parentIdBuilder = new StringBuilder();
        if (parentId.contains(".")) {
            for (String tempId :
                    Arrays.stream(parentId.split("\."))
                            .collect(Collectors.toList())) {
                parentIdBuilder.append(tempId);
            }
        } else {
            parentIdBuilder.append(parentId);
        }

        if (parentIdBuilder.toString().equals(stringBuilder.toString())) {
            TreeNode tempTreeNode = new TreeNode();
            tempTreeNode.setParentId(parentId);
            tempTreeNode.setId(id);
            child.add(tempTreeNode);
        }
    }

}