根據經緯度查詢附近的點



根據給定經緯度(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)的四個位置。所有在這個區域的範圍都在該點附近。

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/

 /** 地球半徑 */
 private static final double EARTH_RADIUS = 6371000;
 /** 範圍距離 */
 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) // 弧度轉換成角度
  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) # 弧度轉換成角度
  double dlat = distance / EARTH_RADIUS;
  dlat = Math.toDegrees(dlat); // # 弧度轉換成角度

  // 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公式計算球面兩點間的距離。"
  // # 經緯度轉換成弧度
  // 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);
 }
}