如何在Java中使用opencv BOWKMeansTrainer？

import org.opencv.core.Mat;
import org.opencv.core.MatOfFloat;
import org.opencv.core.MatOfInt;
import org.opencv.core.MatOfKeyPoint;
import org.opencv.core.TermCriteria;
import org.opencv.features2d.FeatureDetector;
import org.opencv.features2d.DescriptorExtractor;
import org.opencv.features2d.DescriptorMatcher;
import org.opencv.features2d.BOWKMeansTrainer;

BOWKMeansTrainer bowTrainer = new BOWKMeansTrainer(k); // k为聚类的簇数
bowTrainer.setTermCriteria(new TermCriteria(TermCriteria.MAX_ITER, 100, 0.001));

FeatureDetector detector = FeatureDetector.create(FeatureDetector.SIFT);
DescriptorExtractor extractor = DescriptorExtractor.create(DescriptorExtractor.SIFT);
DescriptorMatcher matcher = DescriptorMatcher.create(DescriptorMatcher.BRUTEFORCE);

MatOfKeyPoint keypoints = new MatOfKeyPoint();
Mat descriptors = new Mat();

detector.detect(image, keypoints);
extractor.compute(image, keypoints, descriptors);

bowTrainer.add(descriptors);

Mat vocabulary = bowTrainer.cluster();