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