API文档
http://shengshifeiyang.gitee.io/geotools-learning/

/**
* 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 POLYGON((0 0, 10 0, 10 10, 0 10,0 0))
* @return
*/
public static boolean withinGeo(double x,double y,String geometry) throws ParseException {

        GeometryFactory geometryFactory = new GeometryFactory();

        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);

}

public static void main(String[] args) throws Exception {

//请自行搜素了解wkt格式

//wktPoly 1.点位要有顺序，需要按顺序画成封闭区域；2.最后一个点位和第一个点位相同，完成闭环

        String wktPoly = "POLYGON ((121 29, 121 30, 122 30, 122 29,121 29))";

        String wktPoint = "POINT (121.664564 29.971667)";
        GeometryFactory geometryFactory = new GeometryFactory();
        WKTReader reader = new WKTReader(geometryFactory);
        Geometry point = reader.read(wktPoint);
        Geometry poly = reader.read(wktPoly);
        boolean ex = poly.contains(point);
        System.out.println("ex = " + ex);
        List<String> list = new ArrayList<>();
        list.add("121 29");
        list.add("121 30");
        list.add("122 30");
        list.add("122 29");
        String polygon = "POLYGON (("+ StringUtils.join(list,",")+","+list.get(0)+"))";
        System.out.println(polygon);
        String point1 = "POINT ("+"121.664564"+" "+"29.971667"+")";

        boolean b = withinGeo(121.664564, 29.971667, polygon);
        System.out.println(b);
}

转载：https://blog.51cto.com/u_15127528/4732344