JVA电商秒杀实战（四）
页面优化技术
- 页面缓存
为了提高访问速度，减少对数据库的访问。通过缓存html页面，客户端请求从缓存中获取，没有再手动渲染。
- 页面静态化
实现前后端分离，客户端第一次访问页面，把页面缓存在客户端的浏览器上，再次访问时，就不需要和服务器交互。直接从本地缓存中获取，节约了用户的流量。
- 静态资源优化
- CND优化
页面缓存
当访问goods_list页面时，如果缓存中有，就取出返回这个html；如果没有就获取数据库中的数据，渲染模板，再返回前端之前保存到缓存中。再次获取时，只要缓存中存的这个页面还没过期，就可以直接返回给前端。
@RequestMapping(value = "/to_list",produces = "text/html")@ResponseBodypublic String list(HttpServletRequest request, HttpServletResponse response,Model model, MiaoshaUser user){model.addAttribute("user",user);// return "goods_list";//取缓存String html = redisService.get(GoodsKey.getGoodsList,"",String.class);if (!StringUtils.isEmpty(html)){return html;}//查询商品列表List<GoodsVo> goodsList = goodsService.listGoodsVo();model.addAttribute("goodsList",goodsList);//手动渲染WebContext ctx = new WebContext(request, response, request.getServletContext(), request.getLocale(), model.asMap());html = thymeleafViewResolver.getTemplateEngine().process("goods_list", ctx);
// SpringWebContext ctx = new SpringWebContext(request,response,request.getServletContext(),
// request.getLocale(),model.asMap(),applicationContext);
// html =thymeleafViewResolver.getTemplateEngine().process("goods_list",ctx);if (!StringUtils.isEmpty(html)){redisService.set(GoodsKey.getGoodsList,"",html);}return html;}
页面静态化
127.0.0.1:6379> keys GoodsKey:gl
1) "GoodsKey:gl"
前面缓存了商品详情页面，现在做一个页面静态化，前端只要后端传数据就可以。
- 定义一个GoodsDetailVo封装来专门给页面传值
public class GoodsDetailVo {private int miaoshaStatus = 0;private int remainSeconds = 0;private GoodsVo goods;private MiaoshaUser user;public int getMiaoshaStatus() {return miaoshaStatus;}public void setMiaoshaStatus(int miaoshaStatus) {this.miaoshaStatus = miaoshaStatus;}public int getRemainSeconds() {return remainSeconds;}public void setRemainSeconds(int remainSeconds) {this.remainSeconds = remainSeconds;}public GoodsVo getGoods() {return goods;}public void setGoods(GoodsVo goods) {this.goods = goods;}public MiaoshaUser getUser() {return user;}public void setUser(MiaoshaUser user) {this.user = user;}
}2. 把数据放在GoodsDetailVo对象中传给前端```java@RequestMapping(value="/detail/{goodsId}")@ResponseBodypublic Result<GoodsDetailVo> detail(HttpServletRequest request, HttpServletResponse response, Model model, MiaoshaUser user, @PathVariable("goodsId")long goodsId) {GoodsVo goods = goodsService.getGoodsVoByGoodsId(goodsId);long startAt = goods.getStartDate().getTime();long endAt = goods.getEndDate().getTime();long now = System.currentTimeMillis();int miaoshaStatus = 0;int remainSeconds = 0;if(now < startAt ) {//秒杀还没开始，倒计时miaoshaStatus = 0;remainSeconds = (int)((startAt - now )/1000);}else if(now > endAt){//秒杀已经结束miaoshaStatus = 2;remainSeconds = -1;}else {//秒杀进行中miaoshaStatus = 1;remainSeconds = 0;}GoodsDetailVo vo = new GoodsDetailVo();vo.setGoods(goods);vo.setUser(user);vo.setRemainSeconds(remainSeconds);vo.setMiaoshaStatus(miaoshaStatus);return Result.success(vo);}
}
``
- 秒杀静态化：把之前的返回订单详情页面，改成秒杀成功返回订单信息，失败返回失败信息。
@RequestMapping(value = "/do_miaosha",method = RequestMethod.POST)@ResponseBodypublic Result<OrderInfo> miaosha(Model model, MiaoshaUser user,@RequestParam("goodsId")long goodsId) {model.addAttribute("user",user);if (user == null){return Result.error(CodeMsg.SESSION_ERROR);}//判断库存GoodsVo goods = goodsService.getGoodsVoByGoodsId(goodsId);int stock = goods.getStockCount();if (stock <= 0){return Result.error(CodeMsg.MIAO_SHA_OVER);
// model.addAttribute("errmsg", CodeMsg.MIAO_SHA_OVER.getMsg());
// return "miaosha_fail";}//判断是否已经秒杀过MiaoshaOrder order = orderService.getMiaoshaOrderByUserIdGoodsId(user.getId(),goodsId);if (order != null){return Result.error(CodeMsg.REPEATE_MIAOSHA);
// model.addAttribute("errmsg",CodeMsg.REPEATE_MIAOSHA.getMsg());
// return "miaosha_fail";}//减库存 下订单 写入秒杀订单OrderInfo orderInfo = miaoshaService.miaosha(user,goods);return Result.success(orderInfo);
// model.addAttribute("orderInfo",orderInfo);
// model.addAttribute("goods",goods);
// return "order_detail";}
}
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