import org.osgeo.proj4j.CoordinateTransformFactory; //导入依赖的package包/类
private static Pair<Double, Double> fromHK80toWGS84(Pair<Double, Double> pair) {
    try {
        // reference: blog.tiger-workshop.com/hk1980-grid-to-wgs84/
        CoordinateTransformFactory ctFactory = new CoordinateTransformFactory();
        CRSFactory csFactory = new CRSFactory();
        CoordinateReferenceSystem HK80 = csFactory.createFromParameters("EPSG:2326", "+proj=tmerc +lat_0=22.31213333333334 +lon_0=114.1785555555556 +k=1 +x_0=836694.05 +y_0=819069.8 +ellps=intl +towgs84=-162.619,-276.959,-161.764,0.067753,-2.24365,-1.15883,-1.09425 +units=m +no_defs");
        CoordinateReferenceSystem WGS84 = csFactory.createFromParameters("WGS84", "+proj=longlat +datum=WGS84 +no_defs");
        CoordinateTransform trans = ctFactory.createTransform(HK80, WGS84);
        ProjCoordinate p = new ProjCoordinate();
        ProjCoordinate p2 = new ProjCoordinate();
        p.x = pair.first;
        p.y = pair.second;
        trans.transform(p, p2);
        return new Pair<>(p2.x, p2.y);
    } catch (IllegalStateException e) {
        Timber.e(e);
    }
    return null;
}
 

import org.osgeo.proj4j.CoordinateTransformFactory; //导入依赖的package包/类
/**
 * Convert geometry to different coordinate system given the source/target
 * proj4 parameters. Presumably these were pulled from SPATIAL_REF_SYS.
 *
 * @param geom
 * @param srcParams
 * @param tgtParams
 * @return
 * @throws FunctionExecutionException
 */
public static Geometry transform(Geometry geom, 
                                 String srcParams, 
                                 String tgtParams) 
        throws FunctionExecutionException {
    
    CoordinateTransformFactory ctFactory = new CoordinateTransformFactory();
    CRSFactory crsFactory = new CRSFactory();
    
    CoordinateReferenceSystem srcCrs = crsFactory.createFromParameters(null, srcParams);
    CoordinateReferenceSystem tgtCrs = crsFactory.createFromParameters(null, tgtParams);
    
    CoordinateTransform coordTransform = ctFactory.createTransform(srcCrs, tgtCrs);

    return transformGeometry(coordTransform, geom);
}
 

import org.osgeo.proj4j.CoordinateTransformFactory; //导入依赖的package包/类
/**
 * Transforms the referenced envelope to the specified coordinate reference system
 * using the specified amount of points.
 * <p>
 * This method can handle the case where the envelope contains the North or South pole,
 * or when it cross the +180° longitude.
 *
 * @param targetCRS The target coordinate reference system.
 * @param lenient   {@code true} if datum shift should be applied even if there is
 *                  insuffisient information. Otherwise (if {@code false}), an
 *                  exception is thrown in such case.
 * @param numPointsForTransformation The number of points to use for sampling the envelope.
 * @return The transformed envelope.
 * @throws FactoryException if the math transform can't be determined.
 * @throws TransformException if at least one coordinate can't be transformed.
 *
 * @see CRS#transform(CoordinateOperation, org.opengis.geometry.Envelope)
 *
 * @since 2.3
 */
public ReferencedEnvelope transform(final CoordinateReferenceSystem targetCRS, final int numPointsForTransformation){
    if( this.crs == null ){

         // really this is a the code that created this ReferencedEnvelope
         throw new NullPointerException("Unable to transform referenced envelope, crs has not yet been provided."); 
    }
    /*
     * Gets a first estimation using an algorithm capable to take singularity in account
     * (North pole, South pole, 180° longitude). We will expand this initial box later.
     */
    CoordinateTransformFactory txFactory = new CoordinateTransformFactory();
    CoordinateTransform tx = txFactory.createTransform(crs, targetCRS);
    Envelope transformed = Proj.reproject(envelope, crs, targetCRS);
    
    /*
     * Now expands the box using the usual utility methods.
     */
    //JTS.transform(this, target, transform, numPointsForTransformation);
    // -->
    Envelope expanded = transform(this.envelope,transformed, tx, numPointsForTransformation);
    
    
    return new ReferencedEnvelope(expanded, targetCRS);
}
 

import org.osgeo.proj4j.CoordinateTransformFactory; //导入依赖的package包/类
public static ProjCoordinate latlon2twd67(LatLng latLng) {

        CoordinateTransformFactory ctFactory = new CoordinateTransformFactory();
        CRSFactory csFactory = new CRSFactory();
        CoordinateReferenceSystem crs1 = csFactory.createFromParameters(EPSG_WGS84, FUNC_WGS84);
        CoordinateReferenceSystem crs2 = csFactory.createFromParameters(EPSG_TWD67, FUNC_TWD67);
        CoordinateTransform trans = ctFactory.createTransform(crs1, crs2);
        ProjCoordinate p1 = new ProjCoordinate();
        ProjCoordinate p2 = new ProjCoordinate();
        p1.x = latLng.longitude;
        p1.y = latLng.latitude;
        trans.transform(p1, p2);

        return p2;
    }
 

import org.osgeo.proj4j.CoordinateTransformFactory; //导入依赖的package包/类
public CoordinateTransformFilter(CoordinateReferenceSystem src, CoordinateReferenceSystem dest)
{
  this.src = src;
  this.dest = dest;
  CoordinateTransformFactory ctf = new CoordinateTransformFactory();
  transform = ctf.createTransform(src, dest);
}