地图工具类

package cn.ac.bcc.ebap.modules.gov.utils;/** * @author user 用于地图上的工具类 此工具类,所有牵涉到距离时,距离的单位为米 */public class MapUtils {    /**     * 地球半径     */    public static double EARTH_RADIUS = 6371.393;    /**     * 圆周率π的值     */    public static final double PI = 3.14159265;    /**     * 两个double数比较大小的标识 前者大于后者 返回 1     */    public static final String GREATER_FLAG = "1";    /**     * 两个double数比较大小的标识 前者小于后者返回-1     */    public static final String LESS_FLAG = "-1";    /**     * 两个double数比较大小的标识 前者等于后者返回0     */    public static final String EQUAL_FLAG = "0";    /**     * 计算弧度     *      * @param d     * @return     */    public static double rad(double d) {        return d * Math.PI / 180.0;    }    /**     * 计算两个经纬度之间的距离     *      * @param lat1     * @param lng1     * @param lat2     * @param lng2     * @return     */    public static double GetDistance(double lat1, double lng1, double lat2, double lng2) {        double radLat1 = rad(lat1);        double radLat2 = rad(lat2);        double a = radLat1 - radLat2;        double b = rad(lng1) - rad(lng2);        double s = 2 * Math.asin(Math.sqrt(                Math.pow(Math.sin(a / 2), 2) + Math.cos(radLat1) * Math.cos(radLat2) * Math.pow(Math.sin(b / 2), 2)));        s = s * EARTH_RADIUS;        s = Math.round(s * 1000);        return s;    }    /**     * 根据经纬度和半径计算经纬度范围     *     * @param raidus     *            单位米     * @return minLat, minLng, maxLat, maxLng     */    public static double[] getAround(double lat, double lon, int raidus) {        Double latitude = lat;        Double longitude = lon;        Double degree = (24901 * 1609) / 360.0;        double raidusMile = raidus;        Double dpmLat = 1 / degree;        Double radiusLat = dpmLat * raidusMile;        Double minLat = latitude - radiusLat;        Double maxLat = latitude + radiusLat;        Double mpdLng = degree * Math.cos(latitude * (PI / 180));        Double dpmLng = 1 / mpdLng;        Double radiusLng = dpmLng * raidusMile;        Double minLng = longitude - radiusLng;        Double maxLng = longitude + radiusLng;        return new double[] { minLat, minLng, maxLat, maxLng };    }    /**     * 比较两个double类型的数的大小     *      * @param num1     *            double     * @param num2     * @return 前者大于后者 返回 1;前者小于后者返回-1;前者等于后者返回0     */    public static String comparToDouble(double num1, double num2) {        String flag = "";        Double obj1 = new Double(num1);        Double obj2 = new Double(num2);        int retval = obj1.compareTo(obj2);        if (retval > 0) {            flag = GREATER_FLAG;        } else if (retval < 0) {            flag = LESS_FLAG;        } else {            flag = EQUAL_FLAG;        }        return flag;    }    /**     * 测试     */    public static void main(String[] args) {        double distance = GetDistance(39.935526, 116.421177, 39.93, 116.41);        System.out.println(distance);        double[] around = getAround(39.94, 116.41, 200);        System.out.println("最小维度" + around[0]);        System.out.println("最小经度" + around[1]);        System.out.println("最大维度" + around[2]);        System.out.println("最大经度" + around[3]);        String comparToDouble = comparToDouble(1.1, 1.1);        System.out.println(comparToDouble);    }}

摘取于:
http://blog.csdn.net/vison155142/article/details/52468180
http://blog.csdn.net/kidoo1012/article/details/70214328
https://my.oschina.net/ydsakyclguozi/blog/410505