Spark 中Java實現數據庫Row轉Rating

Dataset<Row> ratings = mlsc.sql("SELECT user,movie,rating FROM data");
JavaRDD<Row> rowJavaRDD = ratings.javaRDD();

JavaRDD<String[]> stringJavaRDD = rowJavaRDD.map(new Function<Row, String[]>() {
    @Override
    public String[] call(Row row) throws Exception {
        String[] st = new String[3];
        st[0] = row.getString(0);
        st[1] = row.getString(1);
        st[2] = row.getString(2);
        return st;
    }
});

JavaRDD<Rating> ratingJavaRDD = stringJavaRDD.map(new Function<String[], Rating>() {
    @Override
    public Rating call(String[] s) throws Exception {
        int user = Integer.parseInt(s[0]);
        int movie = Integer.parseInt(s[1]);
        Double rating = Double.parseDouble(s[2]);
        return new Rating(user,movie,rating);
    }
});