Filter Interceptor Aop

川长思鸟来 2023-10-02 14:54 7阅读 0赞

过滤器 拦截器 AOP切面  
拦截颗粒：过滤器 > 拦截器 > AOP切面 【精细度反之】  
拦截顺序：过滤器 》拦截器 》AOP切面

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## 1.过滤器 ##

基于函数回调，依赖于servlet容器，无法注入Bean；拦截URL,拦截的最前沿,适合公用性强的拦截逻辑,对服务性能影响最小

简单实现@"暴力屏蔽Cors跨越"，过滤器的核心方法是doFilter，通过调整req与res实现过滤功能。

@Component
    public class CorsFilter implements Filter {
    
        public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
            HttpServletResponse response = (HttpServletResponse) res;
            response.setHeader("Access-Control-Allow-Origin", "*");
            response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE, HEAD");
            response.setHeader("Access-Control-Max-Age", "3000");
            response.setHeader("Access-Control-Allow-Headers", "access-control-allow-origin, authority, content-type, version-info, X-Requested-With");
            chain.doFilter(req, res);
        }
    
    }

## 2.拦截器 ##

基于java反射，不依赖于servlet容器，可以注入Bean；拦截URL，在过滤器之后拦截

简单实现@"登录拦截"，拦截器的核心方法是preHandle（前置拦截controller前）、postHandle（后置拦截 页面渲染之前）、afterCompletion（最终拦截 用于销毁关闭资源），通过调整req与res实现过滤功能。

public class LoginHandlerInterceptor implements HandlerInterceptorAdapter {
        
        @Resource
        private LoginCache loginCache；
    
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
            Cookie[] cookies = request.getCookies();
            if (null != cookies && cookies.length >= 1) {
                for (Cookie cookie : cookies) {
                    if (cookie.getName().equals("token")) {
                        return loginCache.exist(cookie.getValue());
                    }
                }
            }
            request.getRequestDispatcher("/").forward(request, response);
            return false;
        }
        
        @Override
        public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
            super.postHandle(request, response, handler, modelAndView);
        }
    
        @Override
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
            super.afterCompletion(request, response, handler, ex);
        }
    }

##    3.AOP切面 ##

基于java反射，拦截包、类、方法、参数

简单实现@"controller日志"。

@Component
    @Aspect
    @Slf4j
    public class ControllerLogAop {
    
        @Around("execution(public *  com.xxx.controller.*.*(..))")
        public Object aroundController(ProceedingJoinPoint point) throws Throwable {
            return writeLog(point);
        }
        private Object writeLog(ProceedingJoinPoint point) throws Throwable {
            String className = point.getTarget().getClass().getName();
            String methodName = point.getSignature().getName();
    
            String reqUrl = StringUtils.EMPTY;
            String reqMethod = StringUtils.EMPTY;
    
            RequestAttributes ra = RequestContextHolder.getRequestAttributes();
            ServletRequestAttributes sra = (ServletRequestAttributes) ra;
            HttpServletRequest request = sra.getRequest();
    
            if (request != null) {
                reqUrl = request.getRequestURL().toString();
                reqMethod = request.getMethod();
            }
    
            long beginTime = System.currentTimeMillis();
            Object result = null;
            Exception ex = null;
            try {
                result = point.proceed();
                return result;
            } catch (Exception e) {
                ex = e;
                throw e;
            } finally {
                long costTime = System.currentTimeMillis() - beginTime;
                if (ex != null) {
                    log.error("[url: {}][method: {}][className: {}][methodName: {}][cost: {} ms][args: {}][发生异常]", reqUrl, reqMethod, className, methodName, costTime, point.getArgs(), ex);
                } else {
                    log.info("[url: {}][method: {}][className: {}][methodName: {}][cost: {} ms][args: {}][return: {}]", reqUrl, reqMethod, className, methodName, costTime, point.getArgs(), new Gson().toJson(result));
                }
            }
        }
    
    }

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