欢迎访问个人博客德鲁大叔撸代码

在前台页面很常见的一种需求是，以树形结构展示具有层级关系的数据。比如企业的部门信息、大部分管理系统的菜单、省市区信息等等。

具体如下图所示

一、表创建以及数据导入

执行下面创建表sql，创建sys_region存具体信息，表信息下载地址sys_region 行政区域表

CREATE TABLE `sys_region` (

`id` int(11) NOT NULL COMMENT '区域主键',

`name` varchar(40) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '区域名称',

`pid` int(11) NULL DEFAULT NULL COMMENT '区域上级标识',

`sname` varchar(40) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '地名简称',

`level` int(11) NULL DEFAULT NULL COMMENT '区域等级',

`citycode` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '区域编码',

`postcode` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '邮政编码',

`mername` varchar(100) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '组合名称',

`lng` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '经度',

`lat` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '纬度',

`pinyin` varchar(100) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '拼音',

`gmt_create` timestamp(0) NULL DEFAULT CURRENT_TIMESTAMP(0) ON UPDATE CURRENT_TIMESTAMP(0) COMMENT '创建时间',

`gmt_modified` timestamp(0) NULL DEFAULT CURRENT_TIMESTAMP(0) ON UPDATE CURRENT_TIMESTAMP(0) COMMENT '修改时间',

`status` char(1) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT '0' COMMENT '状态 0正常 1停用',

PRIMARY KEY (`id`) USING BTREE

) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

二、编写Region实体类(mybatis generator自动生成后增加子区域属性)

@Data

public class Region {

private Integer id;

private String name;

private Integer pid;

private String sname;

private Integer level;

private String citycode;

private String postcode;

private String mername;

private String lng;

private String lat;

private String pinyin;

private Date gmtCreate;

private Date gmtModified;

private String status;

/**

* 子区域

*/

private Listchildren = new ArrayList<>();

}

三、查询接口和mybatis映射文件(省略，只展示查询sql)

select

from sys_region

AND name like concat('%', #{name}, '%')

AND citycode = #{citycode}

order by id

四、组装树形菜单(根据步骤三查到的列表)

1、控制转发层

@RestController

@RequestMapping("/region")

public class RegionController {

@Autowired

private RegionService regionService;

@GetMapping("/list")

public AjaxResult list(Region region){

ListregionList = regionService.selectRegionList(region); // 根据步骤三查到的集合(region表的全部数据)

Listtree = regionService.buildAreaTree(regionList); // 组装一个菜单树

return AjaxResult.success(tree); // 响应返回给前端页面的数据

}

}

2、组装树形菜单入口

@Override

public ListbuildAreaTree(Listregions) {

Listtree = new ArrayList<>();

for(Iteratorit = regions.iterator();it.hasNext();){

Region region = (Region) it.next();

if(region.getPid() == 0){

recursionFn(regions, region); //递归列表

tree.add(region);

}

}

return tree;

3、递归列表

/**

* 递归列表

* @param list

* @param region

*/

private void recursionFn(Listlist, Region region){

// 得到子节点列表

ListchildList = getChildList(list, region);

region.setChildren(childList);

for(Region child : childList){

if(hasChild(list,child)){

//判断是否有子节点

Iteratorit = childList.iterator();

while (it.hasNext()){

Region n = (Region) it.next();

recursionFn(list, n);

}

}

}

}

4、得到子节点列表(得到下级区域)

/**

* 得到子节点列表

* @param list

* @param region

* @return

*/

private ListgetChildList(Listlist, Region region){

Listtlist = new ArrayList();

Iteratorit = list.iterator();

while (it.hasNext()){

Region region1 = (Region) it.next();

if(region1.getPid().longValue() == region.getId().longValue()){

tlist.add(region1);

}

}

return tlist;

}

5、判断是否有下级区域

/**

* 判断是否有子节点

* @param list

* @param region

* @return

*/

private boolean hasChild(Listlist, Region region)

{

return getChildList(list, region).size() > 0 ? true : false;

}

五、postman测试

以省/直辖市为根节点，组装结果35

以陕西省为例，展示具体的市级信息