SpringMVC攔截所有Controller請求，實現自定義參數

1.自定義參數分解器

重寫addArgumentResolvers方法生產參數分解器

需要實現HandlerMethodArgumentResolver接口，
supportsParameter方法返回的是當前方法實例
resolveArgument方法返回時對象類型

上代碼：

// An highlighted block

@Service
public class UserArgumentResolver implements HandlerMethodArgumentResolver {

    @Autowired
    private MiaoShaUserService userService;

    @Override
    public boolean supportsParameter(MethodParameter methodParameter) {
      Class<?> clazz =    methodParameter.getParameterType() ;
      return clazz == MiaoshaUser.class ;
    }

    @Override
    public Object resolveArgument(MethodParameter methodParameter, ModelAndViewContainer modelAndViewContainer, NativeWebRequest webRequest, WebDataBinderFactory webDataBinderFactory) throws Exception {
        /**
         *  threadlocal  線程安全
         */
        return UserContext.getUser();
    }

}

2.重寫攔截器方法

需要繼承HandlerInterceptorAdapter

需要注意的是三個方法： preHandle postHandle afterCompletion

perHandle：執行controller方法之前調用，通常做登錄之前的處理，共同方法，可以獲取方法的註解response,request之類
postHandle：執行controller後，返回modelAndView方法，但未進行頁面渲染的時候調用。
afterCompletion：服務器端已經執行完畢，頁面渲染完畢後執行
上代碼：

// An highlighted block

@Service
public class AccessInterceptor  extends HandlerInterceptorAdapter{

	private static Logger logger = LoggerFactory.getLogger(AccessInterceptor.class);

	@Autowired
	MiaoShaUserService userService;

	@Autowired
	RedisService redisService;

	@Override
	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
			throws Exception {
		/**
		 * 獲取調用 獲取主要方法
		 */
		if(handler instanceof HandlerMethod) {
			logger.info("打印攔截方法handler ：{} ",handler);
			HandlerMethod hm = (HandlerMethod)handler;
			MiaoshaUser user = getUser(request, response);
			UserContext.setUser(user);
			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, SESSION_ERROR);
					return false;
				}
				key += "_" + user.getNickname();
			}else {

			}
			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, ACCESS_LIMIT_REACHED);
	    		return false;
	    	}
		}
		return true;
	}

	@Override
	public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
		super.afterCompletion(request, response, handler, ex);
		UserContext.removeUser();
	}

	private void render(HttpServletResponse response, ResultStatus cm)throws Exception {
		response.setContentType("application/json;charset=UTF-8");
		OutputStream out = response.getOutputStream();
		String str  = JSON.toJSONString(ResultObject.error(cm));
		out.write(str.getBytes("UTF-8"));
		out.flush();
		out.close();
	}

	private MiaoshaUser getUser(HttpServletRequest request, HttpServletResponse response) {
		String paramToken = request.getParameter(MiaoShaUserService.COOKIE_NAME_TOKEN);
		String cookieToken = getCookieValue(request, MiaoShaUserService.COOKIE_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;
	}

2.實現WebMvcConfigurer

需要實現兩個方法

addinterceptors:添加攔截器方法
addArgumentResolvers：添加參數解調器
上代碼：

// An highlighted block

@Configuration
public class WebConfig implements WebMvcConfigurer {

    @Autowired
    UserArgumentResolver resolver;

    @Autowired
    private AccessInterceptor interceptor;
    @Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
        argumentResolvers.add(resolver);
    }
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(interceptor);
    }

然後就可以在controllor方法裏寫參數調用，例如這樣：

// An highlighted block

    @AccessLimit(seconds = 5, maxCount = 5, needLogin = true)
    @RequestMapping(value="/{path}/do_miaosha", method= RequestMethod.POST)
    @ResponseBody
    public ResultObject<Integer> miaosha(Model model, MiaoshaUser user, @PathVariable("path") String path,
                                         @RequestParam("goodsId") long goodsId) {

miaoshaUser就是通過參數解調器實現的。

以上