一、前言
中国省市区还是不少的，省有34个，市有391个，区有1101个，这是以小编的库里的，可能不是最新的，但是个数也差不了多少。
当一次返回所有的数据，并且还要组装成一个三级树，一般的for，会循环34*391*1101次。这样就是千万级的，加上与数据库交互，你跑半天也跑不完。
最后的处理是组长提供的思路，果然很快。
二、思路
首先：小编的省市区是三张表
第一：我们通过三次IO从数据库中查询出所有省市区的数据，下面在进行for循环组装树形效率就很快了！
第二：为了减少IO交互，我们把刚刚取出来的市和区构建为map<provinceCode,List<City>>，map<districtCode,List<District>>，这样效率就上来了！
三、数据库表设计
1. 省
CREATE TABLE `address_province` (
`id` int(11) NOT NULL AUTO_INCREMENT COMMENT 'ID',
`code` char(6) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`name` varchar(16) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`short_name` varchar(16) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`new_code` char(6) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`is_latest` tinyint(3) NULL DEFAULT 1 COMMENT '是否是最新地址，0否1是',
`remarks` varchar(50) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`created_at` datetime(0) NULL DEFAULT NULL COMMENT '创建时间',
`created_by` varchar(16) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`updated_at` datetime(0) NULL DEFAULT NULL COMMENT '更新时间',
`updated_by` varchar(16) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`is_deleted` tinyint(3) UNSIGNED NOT NULL DEFAULT 0 COMMENT '删除标记，0：正常；1：删除',
PRIMARY KEY (`id`) USING BTREE,
UNIQUE INDEX `uk_code`(`code`) USING BTREE,
INDEX `idx_address_province_name`(`name`) USING BTREE,
INDEX `idx_address_province_short_name`(`short_name`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 35 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci COMMENT = '地址省' ROW_FORMAT = Dynamic;
2. 市：
CREATE TABLE `address_city` (
`id` int(11) UNSIGNED NOT NULL AUTO_INCREMENT COMMENT 'ID',
`code` char(6) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`name` varchar(16) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`new_code` char(6) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`province_code` char(6) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`is_latest` tinyint(3) NULL DEFAULT 1 COMMENT '是否是最新地址，0否1是',
`remarks` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`created_at` datetime(0) NULL DEFAULT NULL COMMENT '创建时间',
`created_by` varchar(16) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`updated_at` datetime(0) NULL DEFAULT NULL COMMENT '更新时间',
`updated_by` varchar(16) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`is_deleted` tinyint(3) NULL DEFAULT 0 COMMENT '删除标记，0正常1删除',
PRIMARY KEY (`id`) USING BTREE,
UNIQUE INDEX `uk_code`(`code`) USING BTREE,
INDEX `idx_address_city_name`(`name`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 392 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci COMMENT = '地址市' ROW_FORMAT = Dynamic;
3. 区
CREATE TABLE `address_district` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`code` char(6) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`name` varchar(16) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`new_code` char(6) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`city_code` char(6) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`province_code` char(6) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`is_latest` tinyint(3) NULL DEFAULT 1 COMMENT '是否是最新地址，0否1是',
`remarks` varchar(50) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`created_at` datetime(0) NULL DEFAULT NULL COMMENT '创建时间',
`created_by` varchar(16) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`updated_at` datetime(0) NULL DEFAULT NULL COMMENT '更新时间',
`updated_by` varchar(16) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
`is_deleted` tinyint(3) NULL DEFAULT 0 COMMENT '删除标记，0正常1删除',
PRIMARY KEY (`id`) USING BTREE,
UNIQUE INDEX `uk_code`(`code`) USING BTREE,
INDEX `idx_address_district_name`(`name`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 3110 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci COMMENT = '地址县/区' ROW_FORMAT = Dynamic;
数据量太大了，就不给大家了！
四、具体实现
省市区的实体类就不展示了，大家根据自己公司的设计稍微改动即可使用！
1. 树形VO
/**
* 地址业务父子
*
* @author wangzhenjun
* @date 2022/9/2 16:26
*/
@Data
public class AddressVO implements Serializable {
/**
* ID
*/
@ApiModelProperty(value = "ID")
private Integer id;
/**
* 编码
*/
@ApiModelProperty(value = "")
private String code;
/**
* 名称
*/
@ApiModelProperty(value = "")
private String name;
/**
* 父编码
*/
private String parentCode;
/**
* 市区
*/
private List<AddressVO> children;
}
2. 具体实现
@Override
public Result address() {
long l = System.currentTimeMillis();
// 获取省市区
List<AddressProvince> provinceList = addressProvinceMapper.selectList(Wrappers.<AddressProvince>lambdaQuery().eq(AddressProvince::getIsDeleted, 0).eq(AddressProvince::getIsLatest, 1));
List<AddressCity> cityList = addressCityMapper.selectList(Wrappers.<AddressCity>lambdaQuery().eq(AddressCity::getIsDeleted, 0).eq(AddressCity::getIsLatest, 1));
List<AddressDistrict> districtList = addressDistrictMapper.selectList(Wrappers.<AddressDistrict>lambdaQuery().eq(AddressDistrict::getIsDeleted, 0).eq(AddressDistrict::getIsLatest, 1));
// 按照省code进行分组
Map<String, List<AddressCity>> cityMap = cityList.stream().collect(Collectors.groupingBy(AddressCity::getProvinceCode));
// 按照市code进行分组
Map<String, List<AddressDistrict>> districtMap = districtList.stream().collect(Collectors.groupingBy(AddressDistrict::getCityCode));
List<AddressVO> result = new ArrayList<>();
for (AddressProvince province : provinceList) {
// 获取某个省下的所有市
List<AddressCity> addressCityList = cityMap.get(province.getCode());
// 给树形对象赋省的数据
AddressVO addressProvinceVO = new AddressVO();
addressProvinceVO.setId(province.getId());
addressProvinceVO.setCode(province.getCode());
addressProvinceVO.setName(province.getName());
List<AddressVO> cityResult = new ArrayList<>();
for (AddressCity addressCity : addressCityList) {
// 获取某个市下的所有区
List<AddressDistrict> addressDistrictList = districtMap.get(addressCity.getCode());
// 给树形对象赋市的数据
AddressVO addressCityVO = new AddressVO();
addressCityVO.setId(addressCity.getId());
addressCityVO.setCode(addressCity.getCode());
addressCityVO.setName(addressCity.getName());
addressCityVO.setParentCode(province.getCode());
List<AddressVO> districtResult = new ArrayList<>();
// 便利每个市下面的所有区
for (AddressDistrict addressDistrict : addressDistrictList) {
// 给树形对象赋区的数据
AddressVO addressDistrictVO = new AddressVO();
addressDistrictVO.setId(addressDistrict.getId());
addressDistrictVO.setCode(addressDistrict.getCode());
addressDistrictVO.setName(addressDistrict.getName());
addressDistrictVO.setParentCode(addressCity.getCode());
districtResult.add(addressDistrictVO);
}
addressCityVO.setChildren(districtResult);
cityResult.add(addressCityVO);
}
addressProvinceVO.setChildren(cityResult);
result.add(addressProvinceVO);
}
System.out.println(System.currentTimeMillis() - l);
return Result.success(result);
}
4. 计算时长
我们可以看到，一共297毫秒，小编的机器比较卡，支持cpu在60%情况下，200ms应该问题不大，可以放到redis缓存起来，这样减少IO交互，减少数据库的压力！！
五、前端vue
此时address为数组，按序放了选择的value，
props:可以指定显示和选择的名称，默认是value和label
<el-cascader
v-model="addReceiverForm.address"
placeholder="请选择收货人地址"
:options="options"
:props="{checkStrictly: true,value:'code',label:'name'}"></el-cascader>
========data：============
addReceiverForm:{
address:[]
}
options: [],
========method：============
// 获取省市区
initAddress() {
listAddressAndChild().then(data => {
this.options = data.data
}).catch(() => {
});
},
六、总结
如果大家有比小编更加快的方式，欢迎留言交流哈！
如果觉得有用，还请动动大家的发财小手点点关注哈！！谢谢大家了！！
有缘人才可以看得到的哦！！！欢迎大家关注小编的微信公众号，谢谢大家！