android计算地图上两点距离的算法
接口：
package com.computedistance;public interface DistanceComputeInterface {double getDistance(double lat1, double lng1, double lat2, double lng2);double getShortDistance(double lat1, double lon1, double lat2, double lon2);double getLongDistance(double lat1, double lon1, double lat2, double lon2);double getDistanceBySpeed(double speed, double timeSpace);double getAccurancyDistance(double lat_a, double lng_a, double lat_b, double lng_b);}
实现类：
package com.computedistance.impl;import java.security.InvalidParameterException;import com.baidu.mapapi.utils.DistanceUtil;import com.baidu.platform.comapi.basestruct.GeoPoint;import com.computedistance.DistanceComputeInterface;public class DistanceComputeImpl implements DistanceComputeInterface{private final static double DEF_PI = 3.14159265359; // PIprivate final static double DEF_2PI= 6.28318530712; // 2*PIprivate final static double DEF_PI180= 0.01745329252; // PI/180.0private final static double DEF_R =6370693.5; // radius of earthprivate static DistanceComputeImpl instance = null;public synchronized static DistanceComputeImpl getInstance(){if (instance == null) {instance = new DistanceComputeImpl();}return instance;}private DistanceComputeImpl(){}@Overridepublic double getDistance(double lat1, double lng1, double lat2, double lng2) {GeoPoint p1LL = new GeoPoint((int) (lat1*1e6), (int) (lng1*1e6));GeoPoint p2LL = new GeoPoint((int) (lat2*1e6), (int) (lng2*1e6));double distance = DistanceUtil.getDistance(p1LL, p2LL);return distance/1000;}@Overridepublic double getShortDistance(double lat1, double lon1, double lat2,double lon2) {double ew1, ns1, ew2, ns2;double dx, dy, dew;double distance;// 角度转换为弧度ew1 = lon1 * DEF_PI180;ns1 = lat1 * DEF_PI180;ew2 = lon2 * DEF_PI180;ns2 = lat2 * DEF_PI180;// 经度差dew = ew1 – ew2;// 若跨东经和西经180 度，进行调整if (dew > DEF_PI)dew = DEF_2PI – dew;else if (dew < -DEF_PI)dew = DEF_2PI + dew;dx = DEF_R * Math.cos(ns1) * dew; // 东西方向长度(在纬度圈上的投影长度)dy = DEF_R * (ns1 – ns2); // 南北方向长度(在经度圈上的投影长度)// 勾股定理求斜边长distance = Math.sqrt(dx * dx + dy * dy);return distance/1000;}@Overridepublic double getLongDistance(double lat1, double lon1, double lat2,double lon2) {double ew1, ns1, ew2, ns2;double distance;// 角度转换为弧度ew1 = lon1 * DEF_PI180;ns1 = lat1 * DEF_PI180;ew2 = lon2 * DEF_PI180;ns2 = lat2 * DEF_PI180;// 求大圆劣弧与球心所夹的角(弧度)distance = Math.sin(ns1) * Math.sin(ns2) + Math.cos(ns1) * Math.cos(ns2) * Math.cos(ew1 – ew2);// 调整到[-1..1]范围内，避免溢出if (distance > 1.0){distance = 1.0;} else if (distance < -1.0){distance = -1.0;}// 求大圆劣弧长度distance = DEF_R * Math.acos(distance);return distance/1000;}@Overridepublic double getDistanceBySpeed(double speed, double timeSpace) {if (speed < 0 || timeSpace <= 0) {throw new InvalidParameterException();}return speed * timeSpace;}@Overridepublic double getAccurancyDistance(double lat_a, double lng_a,double lat_b, double lng_b) {double pk = (double) (180 / 3.14169);double a1 = lat_a / pk;double a2 = lng_a / pk;double b1 = lat_b / pk;double b2 = lng_b / pk;double t1 = Math.cos(a1) * Math.cos(a2) * Math.cos(b1) * Math.cos(b2);double t2 = Math.cos(a1) * Math.sin(a2) * Math.cos(b1) * Math.sin(b2);double t3 = Math.sin(a1) * Math.sin(b1);double tt = Math.acos(t1 + t2 + t3);return 6366000 * tt / 1000;}}
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