import org.locationtech.jts.geom.Coordinate;import org.locationtech.jts.geom.Polygon;import org.locationtech.jts.io.ParseException;import java.util.*;import java.util.stream.Collectors;/** * <p>Title : PolygonNodeTriangle </p> * <p>Description : 多邊形自身節點組成三角形</p> * @author huifer * @date 2018/10/15 */public class PolygonNodeTriangle {  private int NUM = 3;  private Set result_p = new HashSet();  public static void main(String[] args) {    //0    double[] point1 = new double[]{0, 0};    //1    double[] point2 = new double[]{10, 0};    //2    double[] point3 = new double[]{20, 0};    //3    double[] point4 = new double[]{10, 10};    List<double[]> allPoint = new ArrayList();    allPoint.add(point1);    allPoint.add(point3);    allPoint.add(point4);    PolygonNodeTriangle polygonCenterPoint = new PolygonNodeTriangle();    // 外圍    Polygon waiwei = polygonCenterPoint.waiwei(point1, point3, point4);    // 節點三角形    List<Polygon> sanjiaoxing = polygonCenterPoint.triangleMothed(allPoint);    // 外圍內所有三角形    List<Polygon> rangeTriangle = polygonCenterPoint.getRangeTriangle(waiwei, sanjiaoxing);    // 重心xy    double[] gravityCenterXY = polygonCenterPoint.getGravityCenterXY(rangeTriangle);    System.out.println(rangeTriangle.size());    System.out.println("================================================");    double[] doubles = polygonCenterPoint. polygonGravityPoint("POLYGON((0 0, 20 0, 10 10, 0 0))");  }  /***   * polygon wkt 計算重心   * @param wkt   * @return   */  private double[] polygonGravityPoint(String wkt) {    if (!wkt.startsWith("POLYGON")) {      return null;    }    Operation operation = new Operation();    // 外圍數據轉 list<double[]>    Polygon waiwei = null;    try {      waiwei = operation.createPolygonByWKT(wkt);    } catch (ParseException e) {      e.printStackTrace();    }    Coordinate[] coordinates = waiwei.getCoordinates();    List<double[]> allP = new ArrayList<>();    Arrays.stream(coordinates).forEach(        s -> {          double nowX = s.x;          double nowY = s.y;          allP.add(new double[]{nowX, nowY});        }    );    List<Polygon> polygons = triangleMothed(allP);    List<Polygon> rangeTriangle1 = getRangeTriangle(waiwei, polygons);    double area = waiwei.getArea();    double[] gravityCenterXY1 = getGravityCenterXY(rangeTriangle1);    return gravityCenterXY1;  }  /***   * 重心值   * @param rangeTriangle   * @return [x, y]   */  private double[] getGravityCenterXY(List<Polygon> rangeTriangle) {    double xArea = 0.0;    double yArea = 0.0;    double aArea = 0.0;    for (Polygon triangle : rangeTriangle) {      Coordinate[] coordinates = triangle.getCoordinates();      double area = triangle.getArea();      double[] oneGR = triangleCenterOfGravity(coordinates[0], coordinates[1], coordinates[2]);      xArea += oneGR[0] * area;      yArea += oneGR[1] * area;      aArea += area;    }    System.out.println("重心X " + xArea / aArea);    System.out.println("重心Y " + yArea / aArea);    return new double[]{xArea / aArea, yArea / aArea};  }  /***   * 范圍內三角形   * @param waiwei   * @param sanjiaoxing   * @return   */  private List<Polygon> getRangeTriangle(Polygon waiwei, List<Polygon> sanjiaoxing) {    List<Polygon> triangle = new ArrayList<>();    // 判斷三角形是否在面內    for (int i = 0; i < sanjiaoxing.size(); i++) {      Polygon polygon = sanjiaoxing.get(i);      boolean within = polygon.within(waiwei);      if (within) {        triangle.add(polygon);      }    }    return triangle;  }  /***   * 三角形重心計算   * @param a   * @param b   * @param c   * @return   */  private double[] triangleCenterOfGravity(Coordinate a, Coordinate b, Coordinate c) {    double gravityX = (a.x + b.x + c.x) / 3;    double gravityY = (a.y + b.y + c.y) / 3;    double[] result = new double[]{gravityX, gravityY};    return result;  }  /***   * 測試用外包圖形   * @return   */  private Polygon waiwei(double[] point1, double[] point3, double[] point4) {    List<double[]> ceshimian = new ArrayList();    ceshimian.add(point1);//    ceshimian.add(point2);//    ceshimian.add(point7);    ceshimian.add(point4);//    ceshimian.add(point6);//    ceshimian.add(point5);    ceshimian.add(point3);    String polygonForList = createPolygonForList(ceshimian);    Operation op = new Operation();    Polygon polygonByWKT = null;    try {      polygonByWKT = op.createPolygonByWKT(polygonForList);      return polygonByWKT;    } catch (ParseException e) {      e.printStackTrace();    }    return null;  }  /***   * 生成所有三角形   * @param allPoint   * @return   */  private List<Polygon> triangleMothed(List<double[]> allPoint) {    // 索引 -> 點坐標    Map<String, double[]> indexOfPoint = new HashMap();    for (int i = 0; i < allPoint.size(); i++) {      indexOfPoint.put(String.valueOf(i), allPoint.get(i));    }    // 排序結果    sort((List) indexOfPoint.keySet().stream().collect(Collectors.toList()), new HashSet());    // 刪除元素相同后的集合    // 所有三角形    List<Polygon> allTriangle = new ArrayList();    for (Object oneDataObj : result_p) {      //這一行數據      Set oneDataList = (Set) oneDataObj;      // 這一行數據的三角形數據      List<double[]> trianglePoint = new ArrayList();      oneDataList.forEach(          s -> trianglePoint.add(indexOfPoint.get(s)          ));      Polygon triangle = createTriangle(trianglePoint);      if (triangle != null) {        allTriangle.add(triangle);      }    }    // 所有三角形結束    return allTriangle;  }  /***   * 從點坐標集合中創建一個面   * @param points   * @return   */  private static String createPolygonForList(List<double[]> points) {    String end = "))";    String res = "POLYGON((";    Operation op = new Operation();    for (double[] point : points) {      String x = Double.toString(point[0]);      String y = Double.toString(point[1]);      res += x + " " + y + ", ";    }    res += Double.toString(points.get(0)[0]) + " " + Double.toString(points.get(0)[1]);    res += end;    try {      op.createPolygonByWKT(res);    } catch (ParseException e) {      e.printStackTrace();    }    return res;  }  /***   * 創建三角形   * @param trianglePoint   * @return polygon   */  private static Polygon createTriangle(List<double[]> trianglePoint) {    Operation op = new Operation();    String triangleWkt;    boolean isTri = isTriangle(trianglePoint);    if (isTri) {      triangleWkt = "POLYGON((" + trianglePoint.get(0)[0] + " " + trianglePoint.get(0)[1] + ", " + trianglePoint.get(1)[0] + " " + trianglePoint.get(1)[1] + ", " + trianglePoint.get(2)[0] + " " + trianglePoint.get(2)[1] + ", " + trianglePoint.get(0)[0] + " " + trianglePoint.get(0)[1] + "))";      try {        Polygon polygonByWKT = op.createPolygonByWKT(triangleWkt);        return polygonByWKT;//        return triangleWkt;      } catch (ParseException e) {        e.printStackTrace();      }    }    return null;  }  /***   * 判斷三角形   * @param trianglePoint   * @return   */  private static boolean isTriangle(List<double[]> trianglePoint) {    double[] doubles = trianglePoint.get(0);    double[] doubles1 = trianglePoint.get(1);    double[] doubles2 = trianglePoint.get(2);    double len = Math.sqrt(Math.pow(doubles[0] - doubles1[0], 2) + Math.pow(doubles[1] - doubles1[1], 2));    double len1 = Math.sqrt(Math.pow(doubles[0] - doubles2[0], 2) + Math.pow(doubles[1] - doubles2[1], 2));    double len2 = Math.sqrt(Math.pow(doubles1[0] - doubles2[0], 2) + Math.pow(doubles1[1] - doubles2[1], 2));    if ((len + len1 > len2) && (len + len2 > len1) && (len1 + len2 > len)) {      return true;    }    return false;  }  /***   * 不重復排列 (元素不相同)   * @param datas   * @param target   */  private void sort(List datas, Set target) {    if (target.size() == this.NUM) {      this.result_p.add(target);      return;    }    for (int i = 0; i < datas.size(); i++) {      List newDatas = new ArrayList(datas);      Set newTarget = new HashSet(target);      newTarget.add(newDatas.get(i));      newDatas.remove(i);      sort(newDatas, newTarget);    }  }}