Filter
新建 TimeFilter
@Componentpublic class TimeFilter implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException { System.out.println("time filter init"); } @Override public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException { System.out.println("time filter start"); long startTime = System.currentTimeMillis(); filterChain.doFilter(servletRequest, servletResponse); long endTime = System.currentTimeMillis(); System.out.println("time filter consume " + (endTime - startTime) + " ms"); System.out.println("time filter end"); } @Override public void destroy() { System.out.println("time filter init"); }}啟動服務器，在瀏覽器輸入：http://localhost:8080/hello?name=tom
可以在控制臺輸出如下結果：
time filter start
name: tom
time filter consume 3 ms
time filter end
可以看到，filter 先執行，再到真正執行 HelloController.sayHello() 方法。
通過 TimeFilter.doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) 方法的參數可以看出，我們只能得到原始的 request 和 response對象，不能得到這個請求被哪個 Controller 以及哪個方法處理了，使用Interceptor 就可以獲得這些信息。
Interceptor
新建 TimeInterceptor
@Componentpublic class TimeInterceptor extends HandlerInterceptorAdapter { private final NamedThreadLocal<Long> startTimeThreadLocal = new NamedThreadLocal<>("startTimeThreadLocal"); @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { System.out.println("time interceptor preHandle"); HandlerMethod handlerMethod = (HandlerMethod) handler; // 獲取處理當前請求的 handler 信息 System.out.println("handler 類：" + handlerMethod.getBeanType().getName()); System.out.println("handler 方法：" + handlerMethod.getMethod().getName()); MethodParameter[] methodParameters = handlerMethod.getMethodParameters(); for (MethodParameter methodParameter : methodParameters) { String parameterName = methodParameter.getParameterName(); // 只能獲取參數的名稱，不能獲取到參數的值 //System.out.println("parameterName: " + parameterName); } // 把當前時間放入 threadLocal startTimeThreadLocal.set(System.currentTimeMillis()); return true; } @Override public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { System.out.println("time interceptor postHandle"); } @Override public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { // 從 threadLocal 取出剛才存入的 startTime Long startTime = startTimeThreadLocal.get(); long endTime = System.currentTimeMillis(); System.out.println("time interceptor consume " + (endTime - startTime) + " ms"); System.out.println("time interceptor afterCompletion"); }}注冊 TimeInterceptor
把 TimeInterceptor 注入 spring 容器
@Configurationpublic class WebConfig extends WebMvcConfigurerAdapter { @Autowired private TimeInterceptor timeInterceptor; @Override public void addInterceptors(InterceptorRegistry registry) { registry.addInterceptor(timeInterceptor); }}啟動服務器，在瀏覽器輸入：http://localhost:8080/hello?name=tom
可以在控制臺輸出如下結果：
time filter starttime interceptor preHandlehandler 類：com.nextyu.demo.web.controller.HelloControllerhandler 方法：sayHelloname: tomtime interceptor postHandletime interceptor consume 40 mstime interceptor afterCompletiontime filter consume 51 mstime filter end
可以看到，filter 先于 interceptor 執行，再到真正執行 HelloController.sayHello() 方法。通過 interceptor 方法上的 handler 參數，我們就可以得到這個請求被哪個 Controller 以及哪個方法處理了。但是不能直接獲取到這個方法上的參數值（在這里就是 HelloController.sayHello(String name) 方法參數 name 的值），通過 Aspect 就可以獲取到。
Aspcet
新建 TimeAspect
@Aspect@Componentpublic class TimeAspect { @Around("execution(* com.nextyu.demo.web.controller.*.*(..))") public Object handleControllerMethod(ProceedingJoinPoint pjp) throws Throwable { System.out.println("time aspect start"); Object[] args = pjp.getArgs(); for (Object arg : args) { System.out.println("arg is " + arg); } long startTime = System.currentTimeMillis(); Object object = pjp.proceed(); long endTime = System.currentTimeMillis(); System.out.println("time aspect consume " + (endTime - startTime) + " ms"); System.out.println("time aspect end"); return object; } }啟動服務器，在瀏覽器輸入：http://localhost:8080/hello?name=tom
可以在控制臺輸出如下結果：
time filter starttime interceptor preHandlehandler 類：com.nextyu.demo.web.controller.HelloControllerhandler 方法：sayHellotime aspect startarg is tomname: tomtime aspect consume 0 mstime aspect endtime interceptor postHandletime interceptor consume 2 mstime interceptor afterCompletiontime filter consume 4 mstime filter end
可以看到，filter 先執行，再到 interceptor 執行，再到 aspect 執行，再到真正執行 HelloController.sayHello() 方法。
我們也獲取到了 HelloController.sayHello(String name) 方法參數 name 的值。
請求攔截過程圖
graph TDhttprequest-->filterfilter-->interceptorinterceptor-->aspectaspect-->controller
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