【Redis】GEO(地理坐标)数据结构

1. GEO简介

GEO就是Geolocation的简写形式代表地理坐标。Redis在3.2版本中加入了对GEO的支持允许存储地理坐标信息帮助我们根据经纬度来检索数据。

1.1 GEO常用命令

常见的命令有

GEOADD添加一个地理空间信息包含经度longitude、纬度latitude、值member

GEODIST计算指定的两个点之间的距离并返回

GEOHASH将指定member的坐标转为hash字符串形式并返回

GEOPOS返回指定member的坐标

GEORADIUS指定圆心、半径找到该圆内包含的所有member并按照与圆心之间的距离排序后返回。6.2以后已废弃

GEOSEARCH在指定范围内搜索member并按照与指定点之间的距离排序后返回。范围可以是圆形或矩形。6.2.新功能

GEOSEARCHSTORE与GEOSEARCH功能一致不过可以把结果存储到一个指定的key。 6.2.新功能

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2. 实战示例

2.1 场景介绍

一个点评平台有多个频道每个频道都有很多个店铺。

我们按照频道类型做分组相同频道的店铺作为同一组以频道id为key存入同一个GEO集合中即可。如下图所示

其中Value值存储店铺的id。

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2.2 实战

2.2.1 将店铺数据导入Redis

在项目中编写一个测试方法将店铺数据导入Redis中

@Test
void loadShopData() {
    //1.查询店铺信息
    List<Shop> list = shopService.list();
    //2.把店铺分组按照typeId分组id一致的放到一个集合
    Map<Long, List<Shop>> map = list.stream().collect(Collectors.groupingBy(Shop::getTypeId));
    //3.分批完成写入
    for (Map.Entry<Long, List<Shop>> entry : map.entrySet()) {
        //3.1.获取类型id
        Long typeId = entry.getKey();
        String key = "shop:geo:" + typeId;
        //3.2.获取同类型的店铺的集合
        List<Shop> value = entry.getValue();
        List<RedisGeoCommands.GeoLocation<String>> locations = new ArrayList<>(value.size());
        //3.3.写入reids GEOADD key 经度 维度 member
        for (Shop shop : value) {
            //stringRedisTemplate.opsForGeo().add(key, new Point(shop.getX(), shop.getY()), shop.getId().toString());
            locations.add(new RedisGeoCommands.GeoLocation<>(
                    shop.getId().toString(),
                    new Point(shop.getX(), shop.getY())
            ));
        }
        stringRedisTemplate.opsForGeo().add(key, locations);
    }
}

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2.2.2 根据地理坐标进行分页查询

前端传递如下参数

• typeId频道id
• current当前页
• x经度
• y维度

后端控制器代码如下

@GetMapping("/of/type")
public Result queryShopByType(
        @RequestParam("typeId") Integer typeId,
        @RequestParam(value = "current", defaultValue = "1") Integer current,
        @RequestParam(value = "x",required = false) Double x,
        @RequestParam(value = "y",required = false) Double y) {
    return shopService.queryShopByType(typeId,current,x,y);
}

业务代码如下

@Override
public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
    //1.判断是否需要根据坐标查询
    if (x == null || y == null) {
        //不需要坐标查询按数据库查询
        Page<Shop> page = lambdaQuery()
                .eq(Shop::getTypeId, typeId)
                .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
        //返回数据
        return Result.ok(page.getRecords());
    }

    //2.计算分页参数
    int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
    int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

    //3.查询redis 按照距离排序、分页。 结果shopId distance
    String key = SHOP_GEO_KEY + typeId;
    GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
            .search(
                    key,
                    GeoReference.fromCoordinate(x, y),
                    new Distance(5, Metrics.KILOMETERS),
                    RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
            );
    //4.解析出id
    if (results == null) {
        return Result.ok(Collections.emptyList());
    }
    List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
    if (list.size() <= from) {
        return Result.ok(Collections.emptyList());
    }
    //4.1.截取 from-end 部分
    List<Long> ids = new ArrayList<>(list.size());
    HashMap<String, Distance> distanceMap = new HashMap<>(list.size());
    list.stream().skip(from).forEach(result -> {
        //4.2.获取店铺id
        String shopIdStr = result.getContent().getName();
        ids.add(Long.valueOf(shopIdStr));
        Distance distance = result.getDistance();
        distanceMap.put(shopIdStr, distance);
    });
    //5.根据id查询shop
    String idStr = StrUtil.join(",", ids);
    List<Shop> shops = lambdaQuery().in(Shop::getId, ids)
            .last("ORDER BY FIELD(id," + idStr + ")")
            .list().stream().map(shop -> {
                shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
                return shop;
            }).collect(Collectors.toList());
    //6.返回
    return Result.ok(shops);
}