PostgreSQL+GeoHash地图点位聚合如何实现代码

CREATE EXTENSION postgis;
CREATE EXTENSION postgis_topology;
CREATE EXTENSION postgis_geohash;

@Type(type="jts_geometry")
@Column(name="geometry",columnDefinition = "geometry(Point,4326)")
@JsonIgnore
private Geometry geometry; // 实体类的Geometry字段

String wkt = "POINT("+longitude+" "+latitude+")"; // longitude 经度，latitude纬度
WKTReader wktReader = new WKTReader();
Geometry geometry = wktReader.read(wkt); // Geometry对象
if(geometry!=null) {
    geometry.setSRID(4326);
}

import org.apache.commons.lang3.StringUtils;
import org.springframework.stereotype.Component;
import java.util.ArrayList;
import java.util.List;
@Component
public class GeoHashUtil {
    public final double Max_Lat = 90;
    public final double Min_Lat = -90;
    public final double Max_Lng = 180;
    public final double Min_Lng = -180;
    private final String[] base32Lookup = {
            "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "b", "c", "d", "e", "f", "g", "h", "j", "k",
            "m", "n", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"
    };
    /**
     * 根据geoHash串获取中心点经纬度
     * @param geoHashCode
     * @return  lng->x  lat->y
     */
    public double[] getSpaceCoordinate(String geoHashCode) {
        if(StringUtils.isBlank(geoHashCode)){
            return new double[2];
        }
        List<Integer> list = base32Decode(geoHashCode);
        String str = convertToIndex(list);
        GeoHashPoint geoHashPoint = splitLatAndLng(str);
        double y = revert(Min_Lat, Max_Lat, geoHashPoint.getLatList());
        double x = revert(Min_Lng, Max_Lng, geoHashPoint.getLngList());
        return new double[]{x, y};
    }
    /**
     * 根据精度获取GeoHash串
     * @param lng 经度 x
     * @param lat 纬度 y
     * @param precise 精度
     * @return
     */
    public String getGeoHash( double lng, double lat, int precise) {
        // 纬度二值串长度
        int latLength;
        //  经度二值串长度
        int lngLength;
        if (precise < 1 || precise > 12) {
            precise = 12;
        }
         latLength = (precise * 5) / 2;
        if (precise % 2 == 0) {
            lngLength = latLength;
        } else {
            lngLength = latLength + 1;
        }
        return encode(lat, lng, latLength, lngLength);
    }
    /**
     * 经纬度二值串合并：偶数位放经度，奇数位放纬度，把2串编码组合生成新串
     *
     */
    public String encode(double lat, double lng, int latLength, int lngLength) {
        if (latLength < 1 || lngLength < 1) {
            return StringUtils.EMPTY;
        }
        List<Character> latList = new ArrayList<>(latLength);
        List<Character> lngList = new ArrayList<>(lngLength);
        // 获取维度二值串
        convert(Min_Lat, Max_Lat, lat, latLength, latList);
        // 获取经度二值串
        convert(Min_Lng, Max_Lng, lng, lngLength, lngList);
        StringBuilder sb = new StringBuilder();
        for (int index = 0; index < latList.size(); index++) {
            sb.append(lngList.get(index)).append(latList.get(index));
        }
//        如果二者长度不一样，说明要求的精度为奇数，经度长度比纬度长度大1
        if (lngLength != latLength) {
            sb.append(lngList.get(lngList.size() - 1));
        }
        return base32Encode(sb.toString());
    }
    /**
     * 将合并的二值串转为base32串
     *
     * @param str 合并的二值串
     * @return base32串
     */
    private String base32Encode(final String str) {
        String unit = "";
        StringBuilder sb = new StringBuilder();
        for (int start = 0; start < str.length(); start = start + 5) {
            unit = str.substring(start, start + 5);
            sb.append(base32Lookup[convertToIndex(unit)]);
        }
        return sb.toString();
    }
    /**
     * 每五个一组将二进制转为十进制
     *
     * @param str 五个为一个unit
     * @return 十进制数
     */
    private int convertToIndex(String str) {
        int length = str.length();
        int result = 0;
        for (int index = 0; index < length; index++) {
            result += str.charAt(index) == '0' ? 0 : 1 << (length - 1 - index);
        }
        return result;
    }
    private void convert(double min, double max, double value, int count, List<Character> list) {
        if (list.size() > (count - 1)) {
            return;
        }
        double mid = (max + min) / 2;
        if (value < mid) {
            list.add('0');
            convert(min, mid, value, count, list);
        } else {
            list.add('1');
            convert(mid, max, value, count, list);
        }
    }
    /**
     * 将二值串转换为经纬度值
     *
     * @param min  区间最小值
     * @param max  区间最大值
     * @param list 二值串列表
     */
    private double revert(double min, double max, List<String> list) {
        double value = 0;
        double mid;
        if (list.size() <= 0) {
            return (max + min) / 2.0;
        }
        for (String flag : list) {
            mid = (max + min) / 2;
            if ("0".equals(flag)) {
                max = mid;
            }
            if ("1".equals(flag)) {
                min = mid;
            }
            value = (max + min) / 2;
        }
        return Double.parseDouble(String.format("%.6f", value));
    }
    /**
     * 分离经度与纬度串
     *
     * @param latAndLngStr 经纬度二值串
     */
    private GeoHashPoint splitLatAndLng(String latAndLngStr) {
        GeoHashPoint geoHashPoint = new GeoHashPoint();
        // 纬度二值串
        List<String> latList = new ArrayList<>();
       // 经度二值串
        List<String> lngList = new ArrayList<>();
        for (int i = 0; i < latAndLngStr.length(); i++) {
//            奇数位，纬度
            if (i % 2 == 1) {
                latList.add(String.valueOf(latAndLngStr.charAt(i)));
            } else {
//                偶数位，经度
                lngList.add(String.valueOf(latAndLngStr.charAt(i)));
            }
        }
        geoHashPoint.setLatList(latList);
        geoHashPoint.setLngList(lngList);
        return geoHashPoint;
    }
    /**
     * 将十进制数转为五个二进制数
     *
     * @param nums 十进制数
     * @return 五个二进制数
     */
    private String convertToIndex(List<Integer> nums) {
        StringBuilder str = new StringBuilder();
        for (Integer num : nums) {
            StringBuilder sb = new StringBuilder(Integer.toBinaryString(num));
            int length = sb.length();
            if (length < 5) {
                for (int i = 0; i < 5 - length; i++) {
                    sb.insert(0, "0");
                }
            }
            str.append(sb);
        }
        return str.toString();
    }
    /**
     * 将base32串转为合并的二值串
     *
     * @param str base32串
     * @return 合并的二值串
     */
    private List<Integer> base32Decode(String str) {
        List<Integer> list = new ArrayList<>();
        for (int i = 0; i < str.length(); i++) {
            String ch = String.valueOf(str.charAt(i));
            for (int j = 0; j < base32Lookup.length; j++) {
                if (base32Lookup[j].equals(ch)) {
                    list.add(j);
                }
            }
        }
        return list;
    }
    public static class GeoHashPoint{
        /**
         * 纬度二值串
         */
        private List<String> latList;
        /**
         * 经度二值串
         */
        private  List<String> lngList;
        public List<String> getLatList() {
            return latList;
        }
        public void setLatList(List<String> latList) {
            this.latList = latList;
        }
        public List<String> getLngList() {
            return lngList;
        }
        public void setLngList(List<String> lngList) {
            this.lngList = lngList;
        }
    }
    public static void main(String[] args) {
        GeoHashUtil geoHashUtil = new GeoHashUtil();
        // 根据精度获取GeoHash串
        String geoHash = geoHashUtil.getGeoHash( 120.234133,30.402616, 12);
        System.out.println(geoHash);
        // 根据geoHash串获取中心点经纬度
        double[] spaceCoordinate = geoHashUtil.getSpaceCoordinate(geoHash);
        System.out.println(spaceCoordinate[0]+","+spaceCoordinate[1]);
    }
}

-- 1. 函数：更新每条数据的geometry和geoHash字段的值
create or replace function func_update_geodata() returns text
as $$
declare
    rec record;
begin
    -- 遍历所有经纬度不为空的数据
    for rec in select * from 表名 where 经纬度 is not null and 经纬度 != ''
    LOOP
        update 表名 set pgis_geometry = st_geomfromtext('POINT('|| longitude ||' '|| latitude ||')', 4326),
                             pgis_geohash = st_geohash(st_geomfromtext('POINT('|| longitude ||' '|| latitude ||')', 4326))
        where id = rec.id;
    END LOOP;
    return 'success';
end;
$$ language plpgsql;
-- 2. 调用
select func_update_geodata();

-- 1. 创建触发器函数
create or replace function func_generate_geodata_to_mytab() returns trigger as $body$
    begin
        update 表名 set pgis_geometry = st_geomfromtext('POINT('|| longitude ||' '|| latitude ||')', 4326),
                             pgis_geohash = st_geohash(st_geomfromtext('POINT('|| longitude ||' '|| latitude ||')', 4326))                  
        where id = NEW.id;
        RETURN NEW;
    end;
$body$ language plpgsql;
-- 2. 创建触发器
create trigger trigger_generate_geodata_to_mytab
after insert or update of 经纬度 on 表名
    for each row execute procedure func_generate_geodata_to_mytab();

-- 查询聚合数据
select t.geohash                            as geohash,
       st_x(st_pointfromgeohash(t.geohash)) as longitude,
       st_y(st_pointfromgeohash(t.geohash)) as latitude,
       t.count                              as aggregationCount
from (
         select left(pgis_geohash, ?2) as geohash, count(*) as count
         from 表名
         where pgis_geohash is not null
           and pgis_geohash != ''
           and case when ?1 != '' then st_contains(st_geometryfromtext(?1, 4326), pgis_geometry) else 1 = 1 end
         group by geohash) t;
/*
1. 【?1】为页面传来的Wkt数据
2. 【?2】为从左边截取geohash的前几位
3. st_x(st_pointfromgeohash('geoHash的值')) 、st_y(st_pointfromgeohash('geoHash的值')) 根据geoHash的值获取聚合后的中心点坐标
*/

-- 查询聚合详情
select *
from 表名
where pgis_geohash is not null and pgis_geohash != ''
  and left(pgis_geohash, ?2) in (?1);
/*
1. 【?1】为geohash值的集合
2. 【?2】为从左边截取geohash的前几位
*/

/**
 * @param list 聚合查询的结果
 * @return     优化后的聚合结果
 */
public List optimizationAggregation(List list){
	// 所有聚合点数量
    long sum = list.stream().mapToLong(T::getCount).sum();
    // 获取平均数
    long average = sum / list.size();
    // 大聚合
	List bigList = new ArrayList<>();
    List smallList = new ArrayList<>();
    for (T item : list) {
        if (item.getCount() < average) {
            smallList.add(item);
        } else {
            bigList.add(item);
        }
    }
    Map<T, List<T>> map = new HashMap<>();
    for(T item : bigList){
        map.put(item, new ArrayList<>());
    }
    for(T smallItem : smallList){
        PGpoint smallPoint = smallItem.getGeoPoint();
        int index = -1;
        // 在bigList找出距离当前聚合点最近的点
        double minDistance = Double.MAX_VALUE;
        for(int i = 0; i < bigList.size(); i++){
            T bigItem = bigList.get(i);
            PGpoint bigPoint = bigItem.getGeoPoint();
            double distance = GeometryUtil.getDistance(smallPoint.x, smallPoint.y, bigPoint.x, bigPoint.y);
            if(distance >= minDistance){
                continue;
            }
            minDistance = distance;
            index = i;
        }
        T bigItem = bigList.get(index);
        List<T> childList = map.get(bigItem);
        if(null == childList){
            childList = new ArrayList<>();
        }
        childList.add(smallItem);
        map.put(bigItem, childList);
    }
    // 结果
    List<T> result = new ArrayList<>();
    map.forEach((key, value)->{
        PGpoint parentPoint = key.getGeoPoint();
        value = value.stream().sorted(Comparator.comparing(T::getCount, Comparator.reverseOrder())).collect(Collectors.toList());
        for(T childItem : value){
            PGpoint childPoint = childItem.getGeoPoint();
            double difX = parentPoint.x-childPoint.x;
            double difY = parentPoint.y-childPoint.y;
            double x = parentPoint.x - (new BigDecimal(difX * childItem.getCount()).divide(new BigDecimal(key.getCount()), 15, RoundingMode.HALF_DOWN).doubleValue());
            double y = parentPoint.y - (new BigDecimal(difY * childItem.getCount()).divide(new BigDecimal(key.getCount()), 15, RoundingMode.HALF_DOWN).doubleValue());
            PGpoint pGpoint = new PGpoint(x, y);
            key.setGeoPoint(pGpoint);
            key.setLongitude(String.valueOf(x));
            key.setLatitude(String.valueOf(y));
            key.setCount(key.getCount() + childItem.getCount());
            if(null == key.getGeohashSet()){
                key.setGeohashSet(new HashSet<>());
            }
            key.getGeohashSet().add(childItem.getGeohash());
        }
        result.add(key);
    });
    return result;
}