http://my.oschina.net/fankun2013/blog/338100
地图供应商比较多，产生了许多地图坐标。地图坐标正确转换是个问题。在之前开发地图应用的时候发现从WGS84坐标系（GPS）转换成某个地图坐标系都比较困难。然后只能使用地图供应商提供的webservice接口转换。百度也提供了免费的webservice接口（限制并发量）。对于少数点的转换性能还可以，但是对于非常多点的转换压力比较大（使用多线程并行计算）.个人感觉比较繁琐，而且很难保证转换的稳定性。
时间飞逝，百度地图更新了新版本，给我们带来了福音，map API中自带了相关坐标的转换，这就省事多了。但是其它的地图貌似没有提供转换API.怎么办呢？真是高手在民间呀，哪个牛人透露转换的算法呢？估计是和百度相关的牛人吧。下面是对算法的收集和整理。提供java版本。js版本参考：http://www.oschina.net/code/snippet_260395_39205
这下使用地图转换就比较准确了。
java版本：
/**
* 坐标转换程序
*
* WGS84坐标系：即地球坐标系，国际上通用的坐标系。Earth GCJ02坐标系：即火星坐标系，WGS84坐标系经加密后的坐标系。Mars BD09坐标系：即百度坐标系，GCJ02坐标系经加密后的坐标系。 Bd09 搜狗坐标系、图吧坐标系等，估计也是在GCJ02基础上加密而成的。
*
* 百度地图API 百度坐标
腾讯搜搜地图API 火星坐标
搜狐搜狗地图API 搜狗坐标*
阿里云地图API 火星坐标
图吧MapBar地图API 图吧坐标
高德MapABC地图API 火星坐标
灵图51ditu地图API 火星坐标
*
* @author fankun
*
*/
public class CoordinateConvert {
private static double PI = Math.PI;
private static double AXIS = 6378245.0; //
private static double OFFSET = 0.00669342162296594323; //(a^2 - b^2) / a^2
private static double X_PI = PI * 3000.0 / 180.0; //GCJ-02=>BD09 火星坐标系=>百度坐标系
public static double[] gcj2BD09(double glat, double glon){
double x = glon;
double y = glat;
double[] latlon = new double[2];
double z = Math.sqrt(x * x + y * y) + 0.00002 * Math.sin(y * X_PI);
double theta = Math.atan2(y, x) + 0.000003 * Math.cos(x * X_PI);
latlon[0] = z * Math.sin(theta) + 0.006;
latlon[1] = z * Math.cos(theta) + 0.0065;
return latlon;
} //BD09=>GCJ-02 百度坐标系=>火星坐标系
public static double[] bd092GCJ(double glat, double glon){
double x = glon - 0.0065;
double y = glat - 0.006;
double[] latlon = new double[2];
double z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * X_PI);
double theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * X_PI);
latlon[0] = z * Math.sin(theta);
latlon[1] = z * Math.cos(theta);
return latlon;
}
//BD09=>WGS84 百度坐标系=>地球坐标系
public static double[] bd092WGS(double glat, double glon){
double[] latlon = bd092GCJ(glat,glon);
return gcj2WGS(latlon[0],latlon[1]);
}
// WGS84=》BD09 地球坐标系=>百度坐标系
public static double[] wgs2BD09(double wgLat, double wgLon) {
double[] latlon = wgs2GCJ(wgLat,wgLon);
return gcj2BD09(latlon[0],latlon[1]);
} // WGS84=》GCJ02 地球坐标系=>火星坐标系
public static double[] wgs2GCJ(double wgLat, double wgLon) {
double[] latlon = new double[2];
if (outOfChina(wgLat, wgLon)){
latlon[0] = wgLat;
latlon[1] = wgLon;
return latlon;
}
double[] deltaD = delta(wgLat,wgLon);
latlon[0] = wgLat + deltaD[0];
latlon[1] = wgLon + deltaD[1];
return latlon;
}
//GCJ02=>WGS84 火星坐标系=>地球坐标系(粗略)
public static double[] gcj2WGS(double glat,double glon){
double[] latlon = new double[2];
if (outOfChina(glat, glon)){
latlon[0] = glat;
latlon[1] = glon;
return latlon;
}
double[] deltaD = delta(glat,glon);
latlon[0] = glat - deltaD[0];
latlon[1] = glon - deltaD[1];
return latlon;
}
//GCJ02=>WGS84 火星坐标系=>地球坐标系（精确）
public static double[] gcj2WGSExactly(double gcjLat,double gcjLon){
double initDelta = 0.01;
double threshold = 0.000000001;
double dLat = initDelta, dLon = initDelta;
double mLat = gcjLat - dLat, mLon = gcjLon - dLon;
double pLat = gcjLat + dLat, pLon = gcjLon + dLon;
double wgsLat, wgsLon, i = 0;
while (true) {
wgsLat = (mLat + pLat) / 2;
wgsLon = (mLon + pLon) / 2;
double[] tmp = wgs2GCJ(wgsLat, wgsLon);
dLat = tmp[0] - gcjLat;
dLon = tmp[1] - gcjLon;
if ((Math.abs(dLat) < threshold) && (Math.abs(dLon) < threshold))
break; if (dLat > 0) pLat = wgsLat; else mLat = wgsLat;
if (dLon > 0) pLon = wgsLon; else mLon = wgsLon; if (++i > 10000) break;
}
double[] latlon = new double[2];
latlon[0] = wgsLat;
latlon[1] = wgsLon;
return latlon;
} //两点距离
public static double distance(double latA, double logA, double latB,double logB){
int earthR = 6371000;
double x = Math.cos(latA*Math.PI/180) * Math.cos(latB*Math.PI/180) * Math.cos((logA-logB)*Math.PI/180);
double y = Math.sin(latA*Math.PI/180) * Math.sin(latB*Math.PI/180);
double s = x + y;
if (s > 1)
s = 1;
if (s < -1)
s = -1;
double alpha = Math.acos(s);
double distance = alpha * earthR;
return distance;
} public static double[] delta(double wgLat, double wgLon){
double[] latlng = new double[2];
double dLat = transformLat(wgLon - 105.0, wgLat - 35.0);
double dLon = transformLon(wgLon - 105.0, wgLat - 35.0);
double radLat = wgLat / 180.0 * PI;
double magic = Math.sin(radLat);
magic = 1 - OFFSET * magic * magic;
double sqrtMagic = Math.sqrt(magic);
dLat = (dLat * 180.0) / ((AXIS * (1 - OFFSET)) / (magic * sqrtMagic) * PI);
dLon = (dLon * 180.0) / (AXIS / sqrtMagic * Math.cos(radLat) * PI);
latlng[0] =dLat;
latlng[1] =dLon;
return latlng;
} public static boolean outOfChina(double lat, double lon){
if (lon < 72.004 || lon > 137.8347)
return true;
if (lat < 0.8293 || lat > 55.8271)
return true;
return false;
} public static double transformLat(double x, double y){
double ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x));
ret += (20.0 * Math.sin(6.0 * x * PI) + 20.0 * Math.sin(2.0 * x * PI)) * 2.0 / 3.0;
ret += (20.0 * Math.sin(y * PI) + 40.0 * Math.sin(y / 3.0 * PI)) * 2.0 / 3.0;
ret += (160.0 * Math.sin(y / 12.0 * PI) + 320 * Math.sin(y * PI / 30.0)) * 2.0 / 3.0;
return ret;
} public static double transformLon(double x, double y){
double ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x));
ret += (20.0 * Math.sin(6.0 * x * PI) + 20.0 * Math.sin(2.0 * x * PI)) * 2.0 / 3.0;
ret += (20.0 * Math.sin(x * PI) + 40.0 * Math.sin(x / 3.0 * PI)) * 2.0 / 3.0;
ret += (150.0 * Math.sin(x / 12.0 * PI) + 300.0 * Math.sin(x / 30.0 * PI)) * 2.0 / 3.0;
return ret;
}
}
