mybatis映射文件使用foreach标签

//根据gid数组查询商品
    @Test
    public void testGoodsByGids(){
        GoodsDao mapper = session.getMapper(GoodsDao.class);
        //当数组为空，即长度为0时，全查
        int[] gids = {2,4};
        List<Goods> goods = mapper.selGoodsByGids(gids);
        for (Goods g : goods){
            System.out.println("商品");
            System.out.println(g);
            System.out.println("==============");
        }
    }

//根据gid数组查询商品
    public List<Goods> selGoodsByGids(@Param("gids") int[] gids);

<!--根据gid数组查询商品-->
    <select id="selGoodsByGids" resultType="Goods">
        <include refid="selGoods"></include>
        <where>
            <if test="gids.length > 0">
                <foreach collection="gids" item="gid"
                         separator="," open="gid in (" close=")">
                    #{gid}
                </foreach>
            </if>
        </where>
    </select>

DEBUG [main] - ==>  Preparing: select * from t_goods WHERE gid in ( ? , ? ) 
DEBUG [main] - ==> Parameters: 2(Integer), 4(Integer)