Pid和id在同一张数据库表中，遍历获取树节点

深碍√TFBOYSˉ_ 2023-10-01 23:02 1阅读 0赞

#### Pid和id在同一表中，遍历获取树节点 ####

*  执行结果
 *  定义keyvalue对象
 *  定义tree结构对象
 *  模拟数据
 *  遍历首级菜单
 *  遍历子对象
 *  启动

## 执行结果 ##

![在这里插入图片描述][aa16d8b50fe148cbad79160d76d77ea0.png]

## 定义keyvalue对象 ##

// keyvalue对象
    @Data
    public class keyvalue {
        
    
        public keyvalue(String pid, String id) {
        
            this.pid = pid;
            this.id = id;
        }
    
        public String pid;
        public String id;
    }

## 定义tree结构对象 ##

@Data
    public class ProjectTree {
        
        private String id;
    
        private String name;
    
        private String childrenId;
    
        private List<ProjectTree> children;
    }

## 模拟数据 ##

public List<keyvalue> keyvalueList()
        {
        
            List<keyvalue> keyvalues = new ArrayList<>();
            keyvalues.add(new keyvalue("", "1001596232348864541"));//top 顶级菜单
            keyvalues.add(new keyvalue("", "1001596232348864542"));//top 顶级菜单
            keyvalues.add(new keyvalue("", "1001596232348864543"));//top 顶级菜单
    
            keyvalues.add(new keyvalue("1001596232348864513", "1001596232348864521"));//1
            keyvalues.add(new keyvalue("1001596232348864514", "1001596232348864522"));//2
            keyvalues.add(new keyvalue("1001596232348864515", "1001596232348864533"));//3
            keyvalues.add(new keyvalue("1001596232348864516", "1001596232348864534"));//4
            keyvalues.add(new keyvalue("1001596232348864517", "1001596232348864535"));//5
    
            keyvalues.add(new keyvalue("1001596232348864518", "1001596232348864513"));//6
            keyvalues.add(new keyvalue("1001596232348864519", "1001596232348864514"));//7
            keyvalues.add(new keyvalue("1001596232348864520", "1001596232348864515"));//8
    
            keyvalues.add(new keyvalue("1001596232348864521", "1001596232348864536"));//9
            keyvalues.add(new keyvalue("1001596232348864522", "1001596232348864537"));//10
            keyvalues.add(new keyvalue("1001596232348864533", "1001596232348864538"));//11
            keyvalues.add(new keyvalue("1001596232348864534", "1001596232348864539"));//12
            keyvalues.add(new keyvalue("1001596232348864535", "1001596232348864540"));//13
    
            keyvalues.add(new keyvalue("1001596232348864536", "1001596232348864546"));//14
            keyvalues.add(new keyvalue("1001596232348864537", "1001596232348864547"));//15
            keyvalues.add(new keyvalue("1001596232348864538", "1001596232348864548"));//16
            keyvalues.add(new keyvalue("1001596232348864539", "1001596232348864549"));//17
            keyvalues.add(new keyvalue("1001596232348864540", "1001596232348864550"));//18
    
            keyvalues.add(new keyvalue("1001596232348864541", "1001596232348864518"));//19
            keyvalues.add(new keyvalue("1001596232348864542", "1001596232348864519"));//20
            keyvalues.add(new keyvalue("1001596232348864543", "1001596232348864520"));//21
    
            return keyvalues;
        }

## 遍历首级菜单 ##

private static List<ProjectTree> getTree(List<ProjectTree> rootList, List<ProjectTree> bodyList) {
        
            if (bodyList != null && !bodyList.isEmpty()) {
        
                //声明一个map，用来过滤已操作过的数据
                Map<String, String> map = new Hashtable<>(bodyList.size());
                rootList.forEach(rootTree -> getChild(rootTree, map, bodyList));
                return rootList;
            } else if (rootList != null) {
        
                //当数据只有父节点
                return rootList;
            }
            return null;
        }

## 遍历子对象 ##

private static void getChild(ProjectTree treeDto, Map<String, String> map, List<ProjectTree> bodyList) {
        
            List<ProjectTree> childList = new ArrayList();
            bodyList.stream()
                    .filter(c -> !map.containsKey(c.getId()))
                    .filter(c -> c.getChildrenId().equals(treeDto.getId()))
                    .forEach(c -> {
        
                        map.put(c.getId(), c.getChildrenId());
                        getChild(c, map, bodyList);
                        childList.add(c);
                    });
            treeDto.setChildren(childList);//子数据集
        }

## 启动 ##

public static List<ProjectTree> startTest() {
        
            List<ProjectTree> rootList = new ArrayList<>(); //根节点对象存放到这里
            List<ProjectTree> bodyList = new ArrayList<>(); //其他节点存放到这里，可以包含根节点
            for (keyvalue keyvalue : keyvalueList()) {
        
                if (keyvalue.getPid().isEmpty()) {
        
                    ProjectTree pj = new ProjectTree();
                    pj.setId(keyvalue.id);
                    pj.setName("一级目录");
                    pj.setChildrenId("");
                    rootList.add(pj);
                } else {
        
                    ProjectTree pj = new ProjectTree();
                    pj.setId(keyvalue.id);
                    pj.setName("子集目录");
                    pj.setChildrenId(keyvalue.pid);
                    bodyList.add(pj);
                }
            }
            List<ProjectTree> stc = getTree(rootList, bodyList);//组装的树返给前端
            return stc;
        }

[aa16d8b50fe148cbad79160d76d77ea0.png]: https://img-blog.csdnimg.cn/aa16d8b50fe148cbad79160d76d77ea0.png