关系判断

1. Geometry之间的关系有如下几种：

1. 如下例子展示了如何使用Equals,Disjoint,Intersects,Within操作：

package com.alibaba.autonavi;

import com.vividsolutions.jts.geom.*;
import com.vividsolutions.jts.io.ParseException;
import com.vividsolutions.jts.io.WKTReader;

/**
 * gemotry之间的关系
 * @author xingxing.dxx
 *
 */
public class GeometryRelated {

    private GeometryFactory geometryFactory = new GeometryFactory();

    /**
     *  两个几何对象是否是重叠的
     * @return
     * @throws ParseException
     */
    public boolean equalsGeo() throws ParseException{
        WKTReader reader = new WKTReader( geometryFactory );
        LineString geometry1 = (LineString) reader.read("LINESTRING(0 0, 2 0, 5 0)");
        LineString geometry2 = (LineString) reader.read("LINESTRING(5 0, 0 0)");
        return geometry1.equals(geometry2);//true
    }

    /**
     * 几何对象没有交点(相邻)
     * @return
     * @throws ParseException
     */
    public boolean disjointGeo() throws ParseException{
        WKTReader reader = new WKTReader( geometryFactory );
        LineString geometry1 = (LineString) reader.read("LINESTRING(0 0, 2 0, 5 0)");
        LineString geometry2 = (LineString) reader.read("LINESTRING(0 1, 0 2)");
        return geometry1.disjoint(geometry2);
    }

    /**
     * 至少一个公共点(相交)
     * @return
     * @throws ParseException
     */
    public boolean intersectsGeo() throws ParseException{
        WKTReader reader = new WKTReader( geometryFactory );
        LineString geometry1 = (LineString) reader.read("LINESTRING(0 0, 2 0, 5 0)");
        LineString geometry2 = (LineString) reader.read("LINESTRING(0 0, 0 2)");
        Geometry interPoint = geometry1.intersection(geometry2);//相交点
        System.out.println(interPoint.toText());//输出 POINT (0 0)
        return geometry1.intersects(geometry2);
    }

    /**
     * 判断以x,y为坐标的点point(x,y)是否在geometry表示的Polygon中
     * @param x
     * @param y
     * @param geometry wkt格式
     * @return
     */
    public boolean withinGeo(double x,double y,String geometry) throws ParseException {

        Coordinate coord = new Coordinate(x,y);
        Point point = geometryFactory.createPoint( coord );

        WKTReader reader = new WKTReader( geometryFactory );
        Polygon polygon = (Polygon) reader.read(geometry);
        return point.within(polygon);
    }
    /**
     * @param args
     * @throws ParseException
     */
    public static void main(String[] args) throws ParseException {
        GeometryRelated gr = new GeometryRelated();
        System.out.println(gr.equalsGeo());
        System.out.println(gr.disjointGeo());
        System.out.println(gr.intersectsGeo());
        System.out.println(gr.withinGeo(5,5,"POLYGON((0 0, 10 0, 10 10, 0 10,0 0))"));
    }

}

关系分析

1. 关系分析有如下几种

2. 我们来看看具体的例子

package com.alibaba.autonavi;

import java.util.ArrayList;
import java.util.List;

import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.geom.LineString;

/**
 * gemotry之间的关系分析
 *
 * @author xingxing.dxx
 */
public class Operation {

    private GeometryFactory geometryFactory = new GeometryFactory();

    /**
     * create a Point
     *
     * @param x
     * @param y
     * @return
     */
    public Coordinate point(double x, double y) {
        return new Coordinate(x, y);
    }

    /**
     * create a line
     *
     * @return
     */
    public LineString createLine(List<Coordinate> points) {
        Coordinate[] coords = (Coordinate[]) points.toArray(new Coordinate[points.size()]);
        LineString line = geometryFactory.createLineString(coords);
        return line;
    }

    /**
     * 返回a指定距离内的多边形和多多边形
     *
     * @param a
     * @param distance
     * @return
     */
    public Geometry bufferGeo(Geometry a, double distance) {
        return a.buffer(distance);
    }

    /**
     * 返回(A)与(B)中距离最近的两个点的距离
     *
     * @param a
     * @param b
     * @return
     */
    public double distanceGeo(Geometry a, Geometry b) {
        return a.distance(b);
    }

    /**
     * 两个几何对象的交集
     *
     * @param a
     * @param b
     * @return
     */
    public Geometry intersectionGeo(Geometry a, Geometry b) {
        return a.intersection(b);
    }

    /**
     * 几何对象合并
     *
     * @param a
     * @param b
     * @return
     */
    public Geometry unionGeo(Geometry a, Geometry b) {
        return a.union(b);
    }

    /**
     * 在A几何对象中有的，但是B几何对象中没有
     *
     * @param a
     * @param b
     * @return
     */
    public Geometry differenceGeo(Geometry a, Geometry b) {
        return a.difference(b);
    }

    public static void main(String[] args) {
        Operation op = new Operation();
        //创建一条线
        List<Coordinate> points1 = new ArrayList<Coordinate>();
        points1.add(op.point(0, 0));
        points1.add(op.point(1, 3));
        points1.add(op.point(2, 3));
        LineString line1 = op.createLine(points1);
        //创建第二条线
        List<Coordinate> points2 = new ArrayList<Coordinate>();
        points2.add(op.point(3, 0));
        points2.add(op.point(3, 3));
        points2.add(op.point(5, 6));
        LineString line2 = op.createLine(points2);

        System.out.println(op.distanceGeo(line1, line2));//out 1.0
        System.out.println(op.intersectionGeo(line1, line2));//out GEOMETRYCOLLECTION EMPTY
        System.out.println(op.unionGeo(line1, line2)); //out MULTILINESTRING ((0 0, 1 3, 2 3), (3 0, 3 3, 5 6))
        System.out.println(op.differenceGeo(line1, line2));//out LINESTRING (0 0, 1 3, 2 3)
    }
}