标签：hello ssi 菜单 在线 getchild map 完成 charset equals
//查询所有分类
List<SugClassificationParam> queryAllList = counterQueryAllclsMapper.queryAllList();
// 组装分类
List<SugClassificationParam> returnList = new ArrayList<>();
// 2.2 提供Map进行缓存，子分类可以快速找到父分类
Map<Integer,SugClassificationParam> cacheMap = new HashMap<>();
for (SugClassificationParam sugClassificationParam : queryAllList){
if(sugClassificationParam.getParentId() == 0){
returnList.add( sugClassificationParam );
}
//将自己添加到map缓存中，方便子分类查找自己
cacheMap.put(sugClassificationParam.getId(), sugClassificationParam);
//子分类从缓存map获取父分类
SugClassificationParam parentList = cacheMap.get(sugClassificationParam.getParentId());
if(parentList != null) {
parentList.getChildren().add(sugClassificationParam);
}
}
递归生成一个如图的菜单，编写两个类数据模型Menu、和创建树形的MenuTree。通过以下过程实现：
1.首先从菜单数据中获取所有根节点。
2.为根节点建立次级子树并拼接上。
3.递归为子节点建立次级子树并接上，直至为末端节点拼接上空的“树”。
首先，编写数据模型Menu。每条菜单有自己的id、父节点parentId、菜单名称text、菜单还拥有次级菜单children。（注意建库时的数据类型要统一）
-- 创建级联分类表
DROP TABLE IF EXISTS `t_counter_type`;
CREATE TABLE `t_counter_type` (
`id` int(32) NOT NULL AUTO_INCREMENT COMMENT ‘分类id‘,
`cls_name` varchar(32) DEFAULT NULL COMMENT ‘分类名称‘,
`cls_descrption` varchar(128) DEFAULT NULL COMMENT ‘分类说明‘,
`parent_id` int(32) DEFAULT NULL COMMENT ‘父级id‘,
`is_praent` int(32) DEFAULT NULL COMMENT ‘创建者‘,
`createTime` datetime DEFAULT NULL COMMENT ‘创建时间‘,
`updateUser` varchar(32) DEFAULT NULL COMMENT ‘修改人‘,
`updateTime` datetime DEFAULT NULL COMMENT ‘修改时间‘,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT=‘建议三级分类表‘;
1 import java.util.List;
2
3 public class Menu {
4 private String id;
5 private String parentId;
6 private String text;
7 private String url;
8 private String yxbz;
9 private List<Menu> children;
10 public Menu(String id,String parentId,String text,String url,String yxbz) {
11 this.id=id;
12 this.parentId=parentId;
13 this.text=text;
14 this.url=url;
15 this.yxbz=yxbz;
16 }
17 /*省略get\set*/
18 }
创建树形结构的类MenuTree。方法getRootNode获取所有根节点，方法builTree将根节点汇总创建树形结构，buildChilTree为节点建立次级树并拼接上当前树，递归调用buildChilTree不断为当前树开枝散叶直至找不到新的子树。完成递归，获取树形结构。
1 import java.util.ArrayList;
2 import java.util.List;
3
4 public class MenuTree {
5 private List<Menu> menuList = new ArrayList<Menu>();
6 public MenuTree(List<Menu> menuList) {
7 this.menuList=menuList;
8 }
9
10 //建立树形结构
11 public List<Menu> builTree(){
12 List<Menu> treeMenus =new ArrayList<Menu>();
13 for(Menu menuNode : getRootNode()) {
14 menuNode=buildChilTree(menuNode);
15 treeMenus.add(menuNode);
16 }
17 return treeMenus;
18 }
19
20 //递归，建立子树形结构
21 private Menu buildChilTree(Menu pNode){
22 List<Menu> chilMenus =new ArrayList<Menu>();
23 for(Menu menuNode : menuList) {
24 if(menuNode.getParentId().equals(pNode.getId())) {
25 chilMenus.add(buildChilTree(menuNode));
26 }
27 }
28 pNode.setChildren(chilMenus);
29 return pNode;
30 }
31
32 //获取根节点
33 private List<Menu> getRootNode() {
34 List<Menu> rootMenuLists =new ArrayList<Menu>();
35 for(Menu menuNode : menuList) {
36 if(menuNode.getParentId().equals("0")) {
37 rootMenuLists.add(menuNode);
38 }
39 }
40 return rootMenuLists;
41 }
42 }
最后，插入一些数据试试效果。得到的json就可以生成图一菜单了。
1 import java.util.ArrayList;
2 import java.util.List;
3 import com.alibaba.fastjson.JSON;
4
5 public class Hello {
6 public static void main(String []args) {
7 List<Menu> menuList= new ArrayList<Menu>();
8 /*插入一些数据*/
9 menuList.add(new Menu("GN001D000","0","系统管理","/admin","Y"));
10 menuList.add(new Menu("GN001D100","GN001D000","权限管理","/admin","Y"));
11 menuList.add(new Menu("GN001D110","GN001D100","密码修改","/admin","Y"));
12 menuList.add(new Menu("GN001D120","GN001D100","新加用户","/admin","Y"));
13 menuList.add(new Menu("GN001D200","GN001D000","系统监控","/admin","Y"));
14 menuList.add(new Menu("GN001D210","GN001D200","在线用户","/admin","Y"));
15 menuList.add(new Menu("GN002D000","0","订阅区","/admin","Y"));
16 menuList.add(new Menu("GN003D000","0","未知领域","/admin","Y"));
17 /*让我们创建树*/
18 MenuTree menuTree =new MenuTree(menuList);
19 menuList=menuTree.builTree();
20 /*转为json看看效果*/
21 String jsonOutput= JSON.toJSONString(menuList);
22 System.out.println(jsonOutput);
23 }
24 }
数据库访问数据的形式
@Service
@Transactional
public class CounterQueryAllclsServiceImpl implements CounterQueryAllclsService {
private static final Logger logger = LoggerFactory.getLogger(CounterQueryAllclsServiceImpl.class);
@Autowired
CounterQueryAllclsMapper counterQueryAllclsMapper;
@Override
public List<SugClassificationParam> queryAllList() {
//第二种方式递归循环
List<SugClassificationParam> clsList = new ArrayList<>();
//查询所有分类
List<SugClassificationParam> queryAllList = counterQueryAllclsMapper.queryAllList();
//创建树
ClsTree clsTree = new ClsTree(queryAllList);
clsList=clsTree.builTree();
//打印json
logger.info("返回结果>>>>" + JSON.toJSONString(clsList));
return clsList;
}
标签：hello ssi 菜单 在线 getchild map 完成 charset equals
原文地址：https://www.cnblogs.com/ibuyco/p/14507316.html
