判断一点是否在多边形内/判断是否在围栏内

/**
  * 判断一点是否在多边形内
  *
  * @param target
  * @param points
  * @return
  */
 public static boolean isPointInPolygon(LatLonPoint target, LatLonPoint[] points) {
     int iSum, iCount, iIndex;
     double dLon1 = 0, dLon2 = 0, dLat1 = 0, dLat2 = 0, dLon;
     if (points.length < 3) {
         return false;
     }
     iSum = 0;
     iCount = points.length;
     for (iIndex = 0; iIndex<iCount;iIndex++) {
         if (iIndex == iCount - 1) {
             dLon1 = points[iIndex].getLongitude();
             dLat1 = points[iIndex].getLatitude();
             dLon2 = points[0].getLongitude();
             dLat2 = points[0].getLatitude();
         } else {
             dLon1 = points[iIndex].getLongitude();
             dLat1 = points[iIndex].getLatitude();
             dLon2 = points[iIndex + 1].getLongitude();
             dLat2 = points[iIndex + 1].getLatitude();
         }

         double ALat = target.getLatitude();
         double ALon = target.getLongitude();
         // 以下语句判断A点是否在边的两端点的水平平行线之间，在则可能有交点，开始判断交点是否在左射线上
         if (((ALat >= dLat1) && (ALat < dLat2)) || ((ALat >= dLat2) && (ALat < dLat1))) {
             if (Math.abs(dLat1 - dLat2) > 0) {
                 //得到 A点向左射线与边的交点的x坐标：
                 dLon = dLon1 - ((dLon1 - dLon2) * (dLat1 - ALat) ) / (dLat1 - dLat2);
                 // 如果交点在A点左侧（说明是做射线与 边的交点），则射线与边的全部交点数加一：
                 if (dLon < ALon) {
                     iSum++;
                 }
             }
         }
     }
     return (iSum % 2) != 0;
 }