JAVA递归实现树型结构

灰太狼 2022-10-29 06:28 124阅读 0赞

近期项目有个需求，需要将组织机构数据拼成树型结构返回至前端。我的做法如下：  
1.由于前端展示使用的组件需要特定的属性key，所以我定义了一个VO对象，代码如下：  
(本人使用了Lombok插件)

package top.yuxuange.vo;
    
    import lombok.Data;
    
    import java.util.List;
    
    @Data
    public class TreeVO {
    
        /**
         * id
         */
        private String id;
    
        /**
         * title
         */
        private String title;
    
        /**
         * 子级
         */
        private List<TreeVO> children;
    }

2.编写树型结构工具类：

这是我数据库中组织机构的根节点CODE的截图

![1][]

package top.yuxuange.util;
    
    import org.springframework.stereotype.Component;
    import top.yuxuange.model.SysDept;
    import top.yuxuange.vo.TreeVO;
    
    import java.util.LinkedList;
    import java.util.List;
    import java.util.stream.Collectors;
    
    /**
     * 获取组织机构树
     *
     * @author yuxuange
     * @Date 2021-02-03
     */
    @Component
    public class TreeUtil {
    
        /**
         * 组织机构表，根节点CODE
         */
        private static final String TREE_ROOT_CODE = "0";
    	
    	/**
    	 * 标准版
    	 */
        public static List<TreeVO> getTree(List<SysDept> record) {
            List<TreeVO> treeList = new LinkedList();
            for (SysDept sysDept : record) {
                if (TREE_ROOT_CODE.equals(sysDept.getParentId())) {
                    TreeVO treeVO = new TreeVO();
                    treeVO.setId(sysDept.getCode());
                    treeVO.setTitle(sysDept.getName());
                    treeVO.setChildren(getChild(sysDept.getCode(), record));
                    treeList.add(treeVO);
                }
            }
            return treeList;
        }
    
        private static List<TreeVO> getChild(String code, List<SysDept> record) {
            List<TreeVO> childrenList = new LinkedList();
            for (SysDept sysDept : record) {
                if (code.equals(sysDept.getParentId())) {
                    TreeVO treeVO = new TreeVO();
                    treeVO.setId(sysDept.getCode());
                    treeVO.setTitle(sysDept.getName());
                    treeVO.setChildren(getChild(sysDept.getCode(), record));
                    childrenList.add(treeVO);
                }
            }
            return childrenList;
        }
    	
    	/**
    	 * lamda表达式版
    	 */
        public static List<TreeVO> getTreeEX(List<SysDept> record){
            return record.stream().filter(sysDept -> {return TREE_ROOT_CODE.equals(sysDept.getParentId());}).map(sysDept -> {
                TreeVO treeVO = new TreeVO();
                treeVO.setId(sysDept.getCode());
                treeVO.setTitle(sysDept.getName());
                treeVO.setChildren(getChildEX(sysDept.getCode(),record));
                return treeVO;
            }).collect(Collectors.toList());
        }
    
    
        private static List<TreeVO> getChildEX(String code,List<SysDept> record){
            return record.stream().filter(sysDept -> {return code.equals(sysDept.getParentId());}).map(sysDept -> {
                TreeVO treeVO = new TreeVO();
                treeVO.setId(sysDept.getCode());
                treeVO.setTitle(sysDept.getName());
                treeVO.setChildren(getChildEX(sysDept.getCode(),record));
                return treeVO;
            }).collect(Collectors.toList());
        }
    }

3.查询数据，调用工具类，返回结果如下：  
![treeResult][]

[1]: /images/20221024/3633ed6f94c0411dac89a8871b74c2ad.png
[treeResult]: /images/20221024/6e99c9674d39413782ecf7462a2c2356.png