如何設計一個秒殺系統

wangsys發表於2021-09-09


一、秒殺介面優化思路：
1、系統初始化把商品數量載入到redis
2、收到請求redis預減庫存，庫存不足直接返回，否則進入3
3、後端請求進入mq佇列，前端顯示請求中
4、請求出隊，生成訂單，減少庫存
5、客戶端輪詢，是否秒殺成功

二、秒殺介面的隱藏：秒殺開始之前先去請求獲取秒殺的地址
1、介面改造帶上PathVariable引數
2、新增生成地址的介面
3、秒殺收到請求先驗證PathVariable

三、圖形驗證碼分散使用者請求：
1、新增生成驗證碼的介面
2、在獲取秒殺路徑的時候，驗證驗證碼
3、ScriptEngine的使用

四、介面防刷：用redis對介面限流

後端主要程式碼：

@Controller
@RequestMapping("/miaosha")
public class MiaoshaController implements InitializingBean {

	@Autowired
	MiaoshaUserService userService;
	
	@Autowired
	RedisService redisService;
	
	@Autowired
	GoodsService goodsService;
	
	@Autowired
	OrderService orderService;
	
	@Autowired
	MiaoshaService miaoshaService;
	
	@Autowired
	MQSender sender;
	
	private HashMap<Long, Boolean> localOverMap =  new HashMap<Long, Boolean>();
	
	/**
	 * 系統初始化
	 * */
	public void afterPropertiesSet() throws Exception {
		List<GoodsVo> goodsList = goodsService.listGoodsVo();
		if(goodsList == null) {
			return;
		}
		for(GoodsVo goods : goodsList) {
			redisService.set(GoodsKey.getMiaoshaGoodsStock, ""+goods.getId(), goods.getStockCount());
			localOverMap.put(goods.getId(), false);
		}
	}
	
	@RequestMapping(value="/reset", method=RequestMethod.GET)
    @ResponseBody
    public Result<Boolean> reset(Model model) {
		List<GoodsVo> goodsList = goodsService.listGoodsVo();
		for(GoodsVo goods : goodsList) {
			goods.setStockCount(10);
			redisService.set(GoodsKey.getMiaoshaGoodsStock, ""+goods.getId(), 10);
			localOverMap.put(goods.getId(), false);
		}
		redisService.delete(OrderKey.getMiaoshaOrderByUidGid);
		redisService.delete(MiaoshaKey.isGoodsOver);
		miaoshaService.reset(goodsList);
		return Result.success(true);
	}
	
 
    @RequestMapping(value="/{path}/do_miaosha", method=RequestMethod.POST)
    @ResponseBody
    public Result<Integer> miaosha(Model model,MiaoshaUser user,
    		@RequestParam("goodsId")long goodsId,
    		@PathVariable("path") String path) {
    	model.addAttribute("user", user);
    	if(user == null) {
    		return Result.error(CodeMsg.SESSION_ERROR);
    	}
    	//驗證path
    	boolean check = miaoshaService.checkPath(user, goodsId, path);
    	if(!check){
    		return Result.error(CodeMsg.REQUEST_ILLEGAL);
    	}
    	//記憶體標記，減少redis訪問
    	boolean over = localOverMap.get(goodsId);
    	if(over) {
    		return Result.error(CodeMsg.MIAO_SHA_OVER);
    	}
    	//預減庫存
    	long stock = redisService.decr(GoodsKey.getMiaoshaGoodsStock, ""+goodsId);//10
    	if(stock < 0) {
    		 localOverMap.put(goodsId, true);
    		return Result.error(CodeMsg.MIAO_SHA_OVER);
    	}
    	//判斷是否已經秒殺到了
    	MiaoshaOrder order = orderService.getMiaoshaOrderByUserIdGoodsId(user.getId(), goodsId);
    	if(order != null) {
    		return Result.error(CodeMsg.REPEATE_MIAOSHA);
    	}
    	//入隊
    	MiaoshaMessage mm = new MiaoshaMessage();
    	mm.setUser(user);
    	mm.setGoodsId(goodsId);
    	sender.sendMiaoshaMessage(mm);
    	return Result.success(0);//排隊中
 
    }
    
    /**
     * orderId：成功
     * -1：秒殺失敗
     * 0： 排隊中
     * */
    @RequestMapping(value="/result", method=RequestMethod.GET)
    @ResponseBody
    public Result<Long> miaoshaResult(Model model,MiaoshaUser user,
    		@RequestParam("goodsId")long goodsId) {
    	model.addAttribute("user", user);
    	if(user == null) {
    		return Result.error(CodeMsg.SESSION_ERROR);
    	}
    	long result  =miaoshaService.getMiaoshaResult(user.getId(), goodsId);
    	return Result.success(result);
    }
    
    @AccessLimit(seconds=5, maxCount=5, needLogin=true)
    @RequestMapping(value="/path", method=RequestMethod.GET)
    @ResponseBody
    public Result<String> getMiaoshaPath(HttpServletRequest request, MiaoshaUser user,
    		@RequestParam("goodsId")long goodsId,
    		@RequestParam(value="verifyCode", defaultValue="0")int verifyCode
    		) {
    	if(user == null) {
    		return Result.error(CodeMsg.SESSION_ERROR);
    	}
    	boolean check = miaoshaService.checkVerifyCode(user, goodsId, verifyCode);
    	if(!check) {
    		return Result.error(CodeMsg.REQUEST_ILLEGAL);
    	}
    	String path  =miaoshaService.createMiaoshaPath(user, goodsId);
    	return Result.success(path);
    }
    
    
    @RequestMapping(value="/verifyCode", method=RequestMethod.GET)
    @ResponseBody
    public Result<String> getMiaoshaVerifyCod(HttpServletResponse response,MiaoshaUser user,
    		@RequestParam("goodsId")long goodsId) {
    	if(user == null) {
    		return Result.error(CodeMsg.SESSION_ERROR);
    	}
    	try {
    		BufferedImage image  = miaoshaService.createVerifyCode(user, goodsId);
    		OutputStream out = response.getOutputStream();
    		ImageIO.write(image, "JPEG", out);
    		out.flush();
    		out.close();
    		return null;
    	}catch(Exception e) {
    		e.printStackTrace();
    		return Result.error(CodeMsg.MIAOSHA_FAIL);
    	}
    }
}

前端主要程式碼：

<div class="row">
        <div class="form-inline">
		  <img id="verifyCodeImg" width="80" height="32"  style="display:none" onclick="refreshVerifyCode()"/>
		  <input id="verifyCode"  class="form-control" style="display:none"/>
		  <button class="btn btn-primary" type="button" id="buyButton"onclick="getMiaoshaPath()">立即秒殺</button>
        </div>
</div>

function getMiaoshaPath(){
	var goodsId = $("#goodsId").val();
	g_showLoading();
	$.ajax({
		url:"/miaosha/path",
		type:"GET",
		data:{
			goodsId:goodsId,
			verifyCode:$("#verifyCode").val()
		},
		success:function(data){
			if(data.code == 0){
				var path = data.data;
				doMiaosha(path);
			}else{
				layer.msg(data.msg);
			}
		},
		error:function(){
			layer.msg("客戶端請求有誤");
		}
	});


function getMiaoshaResult(goodsId){
	g_showLoading();
	$.ajax({
		url:"/miaosha/result",
		type:"GET",
		data:{
			goodsId:$("#goodsId").val(),
		},
		success:function(data){
			if(data.code == 0){
				var result = data.data;
				if(result < 0){
					layer.msg("對不起，秒殺失敗");
				}else if(result == 0){//繼續輪詢
					setTimeout(function(){
						getMiaoshaResult(goodsId);
					}, 200);
				}else{
					layer.confirm("恭喜你，秒殺成功！檢視訂單？", {btn:["確定","取消"]},
							function(){
								window.location.href="/order_detail.htm?orderId="+result;
							},
							function(){
								layer.closeAll();
							});
				}
			}else{
				layer.msg(data.msg);
			}
		},
		error:function(){
			layer.msg("客戶端請求有誤");
		}
	});
}

function doMiaosha(path){
	$.ajax({
		url:"/miaosha/"+path+"/do_miaosha",
		type:"POST",
		data:{
			goodsId:$("#goodsId").val()
		},
		success:function(data){
			if(data.code == 0){
				//window.location.href="/order_detail.htm?orderId="+data.data.id;
				getMiaoshaResult($("#goodsId").val());
			}else{
				layer.msg(data.msg);
			}
		},
		error:function(){
			layer.msg("客戶端請求有誤");
		}
	});
	
}

function refreshVerifyCode(){
	$("#verifyCodeImg").attr("src", "/miaosha/verifyCode?goodsId="+$("#goodsId").val()+"&timestamp="+new Date().getTime());
}

附錄一:資料庫的設計


商品表:
create table Goods (
 id bigint  PRIMARY KEY ,
 goodsName VARCHAR(255) ,
 goodsTitle VARCHAR(255) ,
 goodsImg VARCHAR(255) ,
 goodsDetail VARCHAR(255) ,
 goodsPrice double precision not null ,
 goodsStock INTEGER
 )ENGINE =INNODB DEFAULT  CHARSET= utf8;

秒殺商品表:
create table MiaoshaGoods (
id bigint  PRIMARY KEY ,
 goodsId bigint ,
 stockCount INTEGER ,
 startDate null ,
 endDate null
 )ENGINE =INNODB DEFAULT  CHARSET= utf8;

秒殺訂單表:
create table MiaoshaOrder (
id bigint  PRIMARY KEY ,
 userId bigint ,
 orderId bigint ,
 goodsId bigint
 )ENGINE =INNODB DEFAULT  CHARSET= utf8;

使用者表:
create table MiaoshaUser (
 id bigint  PRIMARY KEY ,
 nickname VARCHAR(255) ,
 password VARCHAR(255) ,
 salt VARCHAR(255) ,
 head VARCHAR(255) ,
 registerDate null ,
 lastLoginDate null ,
 loginCount INTEGER
 )ENGINE =INNODB DEFAULT  CHARSET= utf8;

訂單表:
create table OrderInfo (
id bigint  PRIMARY KEY ,
 userId bigint ,
 goodsId bigint ,
 deliveryAddrId bigint ,
 goodsName VARCHAR(255) ,
 goodsCount INTEGER ,
 goodsPrice double precision not null ,
 orderChannel INTEGER ,
 status INTEGER ,
 createDate null ,
 payDate null
 )ENGINE =INNODB DEFAULT  CHARSET= utf8;

附錄二:攔截器內實現的介面限流

@Retention(RUNTIME)
@Target(METHOD)
public @interface AccessLimit {
	int seconds();
	int maxCount();
	boolean needLogin() default true;
}

@Service
public class AccessInterceptor  extends HandlerInterceptorAdapter{
	
	@Autowired
	MiaoshaUserService userService;
	
	@Autowired
	RedisService redisService;
	
	@Override
	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
			throws Exception {
		if(handler instanceof HandlerMethod) {
			MiaoshaUser user = getUser(request, response);
			UserContext.setUser(user);
			HandlerMethod hm = (HandlerMethod)handler;
			AccessLimit accessLimit = hm.getMethodAnnotation(AccessLimit.class);
			if(accessLimit == null) {
				return true;
			}
			int seconds = accessLimit.seconds();
			int maxCount = accessLimit.maxCount();
			boolean needLogin = accessLimit.needLogin();
			String key = request.getRequestURI();
			if(needLogin) {
				if(user == null) {
					render(response, CodeMsg.SESSION_ERROR);
					return false;
				}
				key += "_" + user.getId();
			}else {
				//do nothing
			}
			AccessKey ak = AccessKey.withExpire(seconds);
			Integer count = redisService.get(ak, key, Integer.class);
	    	if(count  == null) {
	    		 redisService.set(ak, key, 1);
	    	}else if(count < maxCount) {
	    		 redisService.incr(ak, key);
	    	}else {
	    		render(response, CodeMsg.ACCESS_LIMIT_REACHED);
	    		return false;
	    	}
		}
		return true;
	}
	
	private void render(HttpServletResponse response, CodeMsg cm)throws Exception {
		response.setContentType("application/json;charset=UTF-8");
		OutputStream out = response.getOutputStream();
		String str  = JSON.toJSONString(Result.error(cm));
		out.write(str.getBytes("UTF-8"));
		out.flush();
		out.close();
	}

	private MiaoshaUser getUser(HttpServletRequest request, HttpServletResponse response) {
		String paramToken = request.getParameter(MiaoshaUserService.COOKI_NAME_TOKEN);
		String cookieToken = getCookieValue(request, MiaoshaUserService.COOKI_NAME_TOKEN);
		if(StringUtils.isEmpty(cookieToken) && StringUtils.isEmpty(paramToken)) {
			return null;
		}
		String token = StringUtils.isEmpty(paramToken)?cookieToken:paramToken;
		return userService.getByToken(response, token);
	}
	
	private String getCookieValue(HttpServletRequest request, String cookiName) {
		Cookie[]  cookies = request.getCookies();
		if(cookies == null || cookies.length <= 0){
			return null;
		}
		for(Cookie cookie : cookies) {
			if(cookie.getName().equals(cookiName)) {
				return cookie.getValue();
			}
		}
		return null;
	}
	
}

參考程式碼

https://gitee.com/lzhcode/maven-parent/tree/master/lzh-seckill2

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