根据经纬度查询附近的点

大致思想：根据给定经纬度(lat,lng)求出其左上角(left_top),右上角(right_top),左下角(left_bottom)，右下角(right_bottom)的四个位置。所有在这个区域的范围都在该点附近。
参照：http://blog.charlee.li/location-search/

package com.show.common.util;

public class Location {
    private double latitude;
    private double longitude;

    public Location(double latitude, double longitude) {
        this.latitude = latitude;
        this.longitude = longitude;
    }

    public double getLatitude() {
        return latitude;
    }

    public void setLatitude(double latitude) {
        this.latitude = latitude;
    }

    public double getLongitude() {
        return longitude;
    }

    public void setLongitude(double longitude) {
        this.longitude = longitude;
    }

}

package com.show.common.util;

public class LatitudeLontitudeUtil {

    // http://blog.charlee.li/location-search/

    /** 地球半径 */
    private static final double EARTH_RADIUS = 6371000;
    /** 范围距离 */
    private double distance;
    /** 左上角 */
    private Location left_top = null;
    /** 右上角 */
    private Location right_top = null;
    /** 左下角 */
    private Location left_bottom = null;
    /** 右下角 */
    private Location right_bottom = null;

    private LatitudeLontitudeUtil(double distance) {
        this.distance = distance;
    }

    private void getRectangle4Point(double lat, double lng) {

        // float dlng = 2 * asin(sin(distance / (2 * EARTH_RADIUS)) / cos(lat));
        // float dlng = degrees(dlng) // 弧度转换成角度
        double dlng = 2 * Math.asin(Math.sin(distance / (2 * EARTH_RADIUS))
                / Math.cos(lat));
        dlng = Math.toDegrees(dlng);

        // dlat = distance / EARTH_RADIUS
        // dlng = degrees(dlat) # 弧度转换成角度
        double dlat = distance / EARTH_RADIUS;
        dlat = Math.toDegrees(dlat); // # 弧度转换成角度

        // left-top : (lat + dlat, lng - dlng)
        // right-top : (lat + dlat, lng + dlng)
        // left-bottom : (lat - dlat, lng - dlng)
        // right-bottom: (lat - dlat, lng + dlng)
        left_top = new Location(lat + dlat, lng - dlng);
        right_top = new Location(lat + dlat, lng + dlng);
        left_bottom = new Location(lat - dlat, lng - dlng);
        right_bottom = new Location(lat - dlat, lng + dlng);

    }

    public static double hav(double theta) {
        double s = Math.sin(theta / 2);
        return s * s;
    }

    public static double getDistance(double lat0, double lng0, double lat1,
            double lng1) {
        // from math import sin, asin, cos, radians, fabs, sqrt

        // def hav(theta):
        // s = sin(theta / 2)
        // return s * s

        // def get_distance_hav(lat0, lng0, lat1, lng1):
        // "用haversine公式计算球面两点间的距离。"
        // # 经纬度转换成弧度
        // lat0 = radians(lat0)
        // lat1 = radians(lat1)
        // lng0 = radians(lng0)
        // lng1 = radians(lng1)

        // dlng = fabs(lng0 - lng1)
        // dlat = fabs(lat0 - lat1)
        // h = hav(dlat) + cos(lat0) * cos(lat1) * hav(dlng)
        // distance = 2 * EARTH_RADIUS * asin(sqrt(h))

        // return distance
        lat0 = Math.toRadians(lat0);
        lat1 = Math.toRadians(lat1);
        lng0 = Math.toRadians(lng0);
        lng1 = Math.toRadians(lng1);

        double dlng = Math.abs(lng0 - lng1);
        double dlat = Math.abs(lat0 - lat1);
        double h = hav(dlat) + Math.cos(lat0) * Math.cos(lat1) * hav(dlng);
        double distance = 2 * EARTH_RADIUS * Math.asin(Math.sqrt(h));

        return distance;
    }

    public static Location[] getRectangle4Point(double lat, double lng,
            double distance) {
        LatitudeLontitudeUtil llu = new LatitudeLontitudeUtil(distance);
        llu.getRectangle4Point(lat, lng);
        Location[] locations = new Location[4];
        locations[0] = llu.left_top;
        locations[1] = llu.right_top;
        locations[2] = llu.left_bottom;
        locations[3] = llu.right_bottom;
        return locations;
    }

    public static void main(String[] args) {
        double lat = 30.500;
        double lng = 120.500;
        double distance = 500d;
        Location[] locations = LatitudeLontitudeUtil.getRectangle4Point(lat,
                lng, distance);
        String sql = "SELECT * FROM place WHERE lat > "
                + locations[2].getLatitude() + " AND lat < "
                + locations[0].getLatitude() + " AND lng > "
                + locations[0].getLongitude() + " AND lng < "
                + locations[1].getLongitude();
        System.out.println(sql);

        double lat1 = 30.495503391970406;
        double lng1 = 120.49261708577215;
        double d = LatitudeLontitudeUtil.getDistance(lat, lng, lat1, lng1);
        System.out.println(d);
    }
}

文章出自：http://0414.iteye.com/blog/2039199