import org.opencv.core.Rect2d; //导入依赖的package包/类
public static Mat vector_Rect2d_to_Mat(List<Rect2d> rs) {
    Mat res;
    int count = (rs != null) ? rs.size() : 0;
    if (count > 0) {
        res = new Mat(count, 1, CvType.CV_64FC4);
        double[] buff = new double[4 * count];
        for (int i = 0; i < count; i++) {
            Rect2d r = rs.get(i);
            buff[4 * i] = r.x;
            buff[4 * i + 1] = r.y;
            buff[4 * i + 2] = r.width;
            buff[4 * i + 3] = r.height;
        }
        res.put(0, 0, buff);
    } else {
        res = new Mat();
    }
    return res;
}
 

import org.opencv.core.Rect2d; //导入依赖的package包/类
public static void Mat_to_vector_Rect2d(Mat m, List<Rect2d> rs) {
    if (rs == null)
        throw new java.lang.IllegalArgumentException("rs == null");
    int count = m.rows();
    if (CvType.CV_64FC4 != m.type() || m.cols() != 1)
        throw new java.lang.IllegalArgumentException(
                                                     "CvType.CV_64FC4 != m.type() ||  m.rows()!=1\n" + m);

    rs.clear();
    double[] buff = new double[4 * count];
    m.get(0, 0, buff);
    for (int i = 0; i < count; i++) {
        rs.add(new Rect2d(buff[4 * i], buff[4 * i + 1], buff[4 * i + 2], buff[4 * i + 3]));
    }
}