@RequestMapping(value = "/", method = RequestMethod.GET)
public String goToPage(HttpSession session, Map<String, Object> map) {
    logger.info("检查用户是否登录");
    Object userId = checkUser(session);
    if (userId != null) {
        logger.info("获取用户信息");
        User user = userService.get(Integer.parseInt(userId.toString()));
        map.put("user", user);
    }
    logger.info("获取产品分类列表");
    List<Category> categoryList = categoryService.getList(null, null);
    logger.info("获取每个分类下的产品列表");
    for (Category category : categoryList) {
        logger.info("获取分类id为{}的产品集合，按产品ID倒序排序", category.getCategory_id());
        List<Product> productList = productService.getList(new Product().setProduct_category(category), new Byte[]{0, 2}, new OrderUtil("product_id", true), new PageUtil(0, 8));
        if (productList != null) {
            for (Product product : productList) {
                Integer product_id = product.getProduct_id();
                logger.info("获取产品id为{}的产品预览图片信息", product_id);
                product.setSingleProductImageList(productImageService.getList(product_id, (byte) 0, new PageUtil(0, 1)));
            }
        }
        category.setProductList(productList);
    }
    map.put("categoryList", categoryList);
    logger.info("获取促销产品列表");
    List<Product> specialProductList = productService.getList(null, new Byte[]{2}, null, new PageUtil(0, 6));
    map.put("specialProductList", specialProductList);
    logger.info("转到前台主页");
    return "fore/homePage";  

//转到前台天猫-错误页
    @RequestMapping(value = "error", method = RequestMethod.GET)
    public String goToErrorPage() {
        return "fore/errorPage";
    }

    //获取主页分类下产品信息-ajax
    @ResponseBody
    @RequestMapping(value = "product/nav/{category_id}", method = RequestMethod.GET, produces = "application/json;charset=utf-8")
    public String getProductByNav(@PathVariable("category_id") Integer category_id) {
        JSONObject object = new JSONObject();
        if (category_id == null) {
            object.put("success", false);
            return object.toJSONString();
        }
        logger.info("获取分类ID为{}的产品标题数据", category_id);
        List<Product> productList = productService.getTitle(new Product().setProduct_category(new Category().setCategory_id(category_id)), new PageUtil(0, 40));
        List<List<Product>> complexProductList = new ArrayList<>(8);
        List<Product> products = new ArrayList<>(5);
        for (int i = 0; i < productList.size(); i++) {
            //如果临时集合中产品数达到5个，加入到产品二维集合中，并重新实例化临时集合
            if (i % 5 == 0) {
                complexProductList.add(products);
                products = new ArrayList<>(5);
            }
            products.add(productList.get(i));
        }
        complexProductList.add(products);
        Category category = new Category().setCategory_id(category_id).setComplexProductList(complexProductList);
        object.put("success", true);
        object.put("category", category);
        return object.toJSONString();
    }
}

私信拿源码