場景
Java中使用JTS對空間幾何計(jì)算(讀取WKT、距離、點(diǎn)在面內(nèi)、長度、面積、相交等)：
Java中使用JTS對空間幾何計(jì)算(讀取WKT、距離、點(diǎn)在面內(nèi)、長度、面積、相交等)_jts-core_霸道流氓氣質(zhì)的博客-CSDN博客
Java+GeoTools實(shí)現(xiàn)WKT數(shù)據(jù)根據(jù)EPSG編碼進(jìn)行坐標(biāo)系轉(zhuǎn)換：
Java+GeoTools實(shí)現(xiàn)WKT數(shù)據(jù)根據(jù)EPSG編碼進(jìn)行坐標(biāo)系轉(zhuǎn)換_霸道流氓氣質(zhì)的博客-CSDN博客
基于gis的業(yè)務(wù)場景中，需要在地圖中錄入?yún)^(qū)域數(shù)據(jù)的wkt數(shù)據(jù)，然后根據(jù)某個坐標(biāo)點(diǎn)判斷是屬于哪個區(qū)域，
以及距離所屬區(qū)域中最近的端點(diǎn)的方位角，比如坐標(biāo)點(diǎn)位于某區(qū)域東南方向100米。
注：
博客：
霸道流氓氣質(zhì)_C#,架構(gòu)之路,SpringBoot-CSDN博客
實(shí)現(xiàn)
1、參考上面引入jts的依賴。
首先數(shù)據(jù)庫中存儲的所有線的WKT數(shù)據(jù)為
其中region_name為線的名稱，region_wkt為線的wkt字符串。
首先從數(shù)據(jù)庫中讀取所有的wkt字符串?dāng)?shù)據(jù)，并轉(zhuǎn)換為map類型數(shù)據(jù)方便處理以及賦值線的名稱到linestring的userData字段。
??????? List<LineString> regionList = new ArrayList<>();
??????? Map<String, List<LineString>> regionMap = new HashMap<>();
??????? //讀取錄入的區(qū)域位置信息
??????? RegionManagement param = RegionManagement.builder().deleteFlag(false).build();
??????? List<RegionManagement> regionManagements = regionManagementMapper.selectList(param);
??????? for (RegionManagement regionManagement : regionManagements) {
??????????? LineString lineString = readWKT(regionManagement.getRegionWKT());
??????????? RegionDTO regionDTO = JSON.parseObject(JSON.toJSONString(regionManagement), RegionDTO.class);
??????????? regionDTO.setUpdateTime(regionManagement.getUpdateTime().toString());
??????????? lineString.setUserData(regionDTO);
??????????? regionList.add(lineString);
??????? }
??????? //將區(qū)域list流處理為map，方便快速查找
??????? Map<String, List<RegionManagement>> collect = regionManagements.stream().collect(Collectors.groupingBy(RegionManagement::getRegionName));
??????? for (String name : collect.keySet()) {
??????????? List<LineString> tmp = new ArrayList<>();
??????????? collect.get(name).forEach(item -> tmp.add(readWKT(item.getRegionWKT())));
??????????? regionMap.put(name, tmp);
??????? }這里的RegionManagement用來讀取數(shù)據(jù)庫中存儲的wkt字符串等數(shù)據(jù)，實(shí)現(xiàn)為
import com.fasterxml.jackson.annotation.JsonFormat;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.util.Date;
@Data
@NoArgsConstructor
@AllArgsConstructor
@Builder
public class RegionManagement {
??? private Long id;
??? private String regionName;
??? private String regionWKT;
??? // 0 false ; 1 true
??? private boolean deleteFlag;
??? @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")
??? private Date updateTime;
}調(diào)用讀取wkt字符串并轉(zhuǎn)換為jts的LineString對象的方法readWKT實(shí)現(xiàn)為
??? //讀取wkt數(shù)據(jù)為LineString
??? public LineString readWKT(String regionWKT){
??????? GeometryFactory fact = new GeometryFactory();
??????? WKTReader reader = new WKTReader(fact);
??????? LineString geometry1 = null;
??????? try {
??????????? geometry1 = (LineString) reader.read(regionWKT);
??????? } catch (ParseException e) {
??????????? e.printStackTrace();
??????? }
??????? return geometry1;
??? }中間獲取所需要的數(shù)據(jù)的RegionDTO的實(shí)現(xiàn)為
import lombok.Data;
@Data
public class RegionDTO {
??? private Long id;
??? private String regionName;
??? private String updateTime;
}2、將要判斷方位的坐標(biāo)值聲明為Point2D對象
??????? //目標(biāo)點(diǎn)位
??????? Point2D.Double carPoint = new Point2D.Double(36582834.745, 4259820.7951);3、獲取距離目標(biāo)點(diǎn)位最近的線
??????? //獲取離目標(biāo)點(diǎn)位最近的線
??????? LineString lineString = findNearestLine(carPoint, 10D, regionList);這里調(diào)用的findNearestLine方法的實(shí)現(xiàn)
??? //查找最近的線，jts工具做線的緩沖區(qū)，擴(kuò)展寬度為10
??? public? LineString findNearestLine(java.awt.geom.Point2D.Double point, Double FuzzyLookupRange, List<LineString> lineStringList) {
??????? Point a = createPoint(point.getX(), point.getY());
??????? return lineStringList.parallelStream().filter((lineString) -> lineString.buffer(FuzzyLookupRange).contains(a)).min((o1, o2) -> {
??????????? Double ax = o1.distance(a);
??????????? Double axx = o2.distance(a);
??????????? return ax.compareTo(axx);
??????? }).orElse(null);
??? }這里調(diào)用了createPoint用來創(chuàng)建point對象
??? //根據(jù)坐標(biāo)x y創(chuàng)建點(diǎn)對象
??? public static Point createPoint(Double x, Double y) {
??????? GeometryFactory a = JTSFactoryFinder.getGeometryFactory();
??????? return a.createPoint(new Coordinate(x, y));
??? }然后使用lineString.buffer方法對線做緩沖區(qū)，擴(kuò)展寬度為10，即將線向外擴(kuò)充成類似區(qū)域的概念，判斷點(diǎn)是否在擴(kuò)充后
的區(qū)域內(nèi)，如果有多個區(qū)域，則取距離最小的一個。
LineString.buffer方法的使用可參考：
Geometry (JTS Topology Suite 1.13 API) - Javadoc Extreme)
Computes a buffer area around this geometry having the given width. The buffer of a Geometry is the Minkowski sum or difference of the geometry
with a disc of radius abs(distance).
Mathematically-exact buffer area boundaries can contain circular arcs.
To represent these arcs using linear geometry they must be approximated with line segments.
The buffer geometry is constructed using 8 segments per quadrant to approximate the circular arcs. The end cap style is CAP_ROUND.
The buffer operation always returns a polygonal result. The negative or zero-distance buffer of lines and points is always an empty Polygon.
?This is also the result for the buffers of degenerate (zero-area) polygons.
直譯：
計(jì)算具有給定寬度的幾何體周圍的緩沖區(qū)。幾何體的緩沖區(qū)是具有半徑為abs（距離）的圓盤的幾何體的Minkowski和或差。
數(shù)學(xué)上精確的緩沖區(qū)邊界可以包含圓弧。要使用線性幾何圖形表示這些圓弧，必須使用線段對其進(jìn)行近似。
緩沖區(qū)幾何結(jié)構(gòu)使用每個象限8個線段來近似圓弧。端蓋樣式為cap_ROUND。
緩沖區(qū)操作總是返回多邊形結(jié)果。直線和點(diǎn)的負(fù)或零距離緩沖區(qū)始終為空多邊形。
這也是退化（零面積）多邊形緩沖區(qū)的結(jié)果。
然后獲取距離最近的線的名稱并輸出
??????? //獲取離目標(biāo)點(diǎn)位最近的線
??????? LineString lineString = findNearestLine(carPoint, 10D, regionList);
??????? String regionName = "區(qū)域位置為空";
??????? if (lineString != null) {
??????????? RegionDTO userData = (RegionDTO) lineString.getUserData();
??????????? regionName = userData.getRegionName();
??????? }
??????? System.out.println(regionName);4、獲取坐標(biāo)點(diǎn)相對于該線的方位角
??????? String azimuth;
??????? if (!regionName.equals("區(qū)域位置為空")) {
??????????? List<LineString> lineStringList = regionMap.get(regionName);
??????????? LineString closeLine;
??????????? if (lineStringList.size() > 1) {
??????????????? closeLine = findNearestLine(carPoint, 10D, lineStringList);
??????????? } else {
??????????????? closeLine = lineStringList.get(0);
??????????? }
??????????? //獲取線的兩個端點(diǎn)
??????????? Point startPoint = closeLine.getStartPoint();
??????????? Point endPoint = closeLine.getEndPoint();
??????????? //獲取點(diǎn)位到兩個端點(diǎn)的距離
??????????? double startDistance = startPoint.distance(createPoint(carPoint.getX(), carPoint.getY()));
??????????? double endDistance = endPoint.distance(createPoint(carPoint.getX(), carPoint.getY()));
??????????? //獲取較近的點(diǎn)作為參考點(diǎn)判斷方位距離
??????????? if (startDistance <= endDistance) {
??????????????? //獲取方位角
??????????????? azimuth = regionName + DirectionUtil.getAzimuth(startPoint.getX(), startPoint.getY(), carPoint.getX(), carPoint.getY()) + "方向路口" + BigDecimal.valueOf(startDistance).intValue() + "米";
??????????? } else {
??????????????? azimuth = regionName + DirectionUtil.getAzimuth(endPoint.getX(), endPoint.getY(), carPoint.getX(), carPoint.getY()) + "方向路口" + BigDecimal.valueOf(endDistance).intValue() + "米";
??????????? }
??????? } else {
??????????? azimuth = "[" + carPoint.getX() + "," + carPoint.getY() + "]";
??????? }
??????? System.out.println(azimuth);其中獲取方位角的工具類DirectionUtil.getAzimuth實(shí)現(xiàn)
import org.locationtech.jts.geom.LineSegment;
public class DirectionUtil {
??? /**
???? * 笛卡爾坐標(biāo)系
???? */
??? enum DirectionEnum {
??????? DUE_EAST("正東", "==0 || ==360"),
??????? DUE_NORTHEAST("東北", "==45"),
??????? DUE_NORTH("正北", "==90"),
??????? NORTH_NORTHWEST("西北", "90<theta<135"),
??????? DUE_WEST("正西", "==180"),
??????? WEST_SOUTHWEST("西南", "180<theta<225"),
??????? DUE_SOUTH("正南", "==270"),
??????? DUE_SOUTHEAST("東南", "==315");
??????? private String direction;
??????? private String describe;
??????? DirectionEnum(String direction, String describe) {
??????????? this.direction = direction;
??????????? this.describe = describe;
??????? }
??????? public String getDirection() {
??????????? return direction;
??????? }
??????? public void setDirection(String direction) {
??????????? this.direction = direction;
??????? }
??????? public String getDescribe() {
??????????? return describe;
??????? }
??????? public void setDescribe(String describe) {
??????????? this.describe = describe;
??????? }
??? }
??? /**
???? * 獲取方位角
???? *
???? * @param x1 觀測點(diǎn)x
???? * @param y1 觀測點(diǎn)y
???? * @param x2 目標(biāo)點(diǎn)x
???? * @param y2 目標(biāo)點(diǎn)y
???? * @return 返回距離觀測點(diǎn)的方位角
???? */
??? public static String getAzimuth(double x1, double y1, double x2, double y2) {
??????? LineSegment lineSegment = new LineSegment(x1, y1, x2, y2);
??????? double angle1 = lineSegment.angle();
??????? double angle = Math.toDegrees(lineSegment.angle());
??????? if (angle < 0) {
??????????? angle = angle + 360;
??????? }
??????? if ((0 < angle && angle < 12.5) || (347.5 < angle && angle < 360)) {
??????????? return DirectionEnum.DUE_EAST.getDirection();
??????? } else if (12.5 < angle && angle < 77.5) {
??????????? return DirectionEnum.DUE_NORTHEAST.getDirection();
??????? } else if (77.5 < angle && angle < 102.5) {
??????????? return DirectionEnum.DUE_NORTH.getDirection();
??????? } else if (102.5 < angle && angle < 167.5) {
??????????? return DirectionEnum.NORTH_NORTHWEST.getDirection();
??????? } else if (167.5 < angle && angle < 192.5) {
??????????? return DirectionEnum.DUE_WEST.getDirection();
??????? } else if (192.5 < angle && angle < 257.5) {
??????????? return DirectionEnum.WEST_SOUTHWEST.getDirection();
??????? } else if (257.5 < angle && angle < 282.5) {
??????????? return DirectionEnum.DUE_SOUTH.getDirection();
??????? } else if (282.5 < angle && angle < 347.5) {
??????????? return DirectionEnum.WEST_SOUTHWEST.getDirection();
??????? } else {
??????????? return "ERROR";
??????? }
??? }
}邏輯就是對比目標(biāo)點(diǎn)到線的兩個端點(diǎn)的距離，取較近的進(jìn)行判斷，然后做方位角判斷。
運(yùn)行效果測試文章來源：http://www.zghlxwxcb.cn/news/detail-707500.html
文章來源地址http://www.zghlxwxcb.cn/news/detail-707500.html
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