Java树形结构

表结构

create table common_tree
(
    id            bigint       not null comment '主键' primary key,
    p_id          bigint       null comment '父节点id',
    tree_code     varchar(100) null comment '树形区分',
    tree_describe varchar(255) null comment '树形描述',
    node_name     varchar(200) null comment '节点名称',
    node_value    varchar(100) null comment '节点值',
    node_index    int          null comment '排序'
)
    comment '树形结构表';

代码

import org.springframework.stereotype.Service;
import tk.mybatis.mapper.entity.Example;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.List;

/**
 * 
 *
 * @author : mc
 * @date : 2023-03-15 10:20
 */
@Service
public class CommonTreeBiz {

    @Resource
    private UCommonTreeMapper treeMapper;

    public List<UCommonTree> buildTree(CommonTreeCodeEnum treeCodeEnum) {
        List<UCommonTree> treeList = new ArrayList<>();

        List<UCommonTree> trees = selectTree(treeCodeEnum);
        for (UCommonTree tree : this.getRootNode(trees)) {
            this.buildChilTree(tree, trees);
            treeList.add(tree);
        }
        return treeList;
    }

    private List<UCommonTree> selectTree(CommonTreeCodeEnum treeCodeEnum) {
        Example example = new Example(UCommonTree.class);
        Example.Criteria criteria = example.createCriteria();
        criteria.andEqualTo("treeCode", treeCodeEnum.getCode());
        criteria.andEqualTo("disableFlag", "1");
        example.setOrderByClause("node_index asc");
        return treeMapper.selectByExample(example);
    }

    private List<UCommonTree> getRootNode(List<UCommonTree> trees) {
        List<UCommonTree> rootList = new ArrayList<>();
        for (UCommonTree tree : trees) {
            if (tree.getPId().equals("0")) {
                rootList.add(tree);
            }
        }
        return rootList;
    }

    private UCommonTree buildChilTree(UCommonTree tree, List<UCommonTree> list) {
        List<UCommonTree> treeList = new ArrayList<>();
        for (UCommonTree t : list) {
            if (t.getPId().equals(tree.getId())) {
                treeList.add(this.buildChilTree(t, list));
            }
        }
        tree.setChildren(treeList);
        return tree;
    }
}