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"); }} 启动服务器，在浏览器输入：http://localhost:8080/hello?name=tom
可以在控制台输出如下结果：
time filter start
name: tom
time filter consume 3 ms
time filter end
可以看到，filter 先执行，再到真正执行 HelloController.sayHello() 方法。
通过 TimeFilter.doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) 方法的参数可以看出，我们只能得到原始的 request 和 response对象，不能得到这个请求被哪个 Controller 以及哪个方法处理了，使用Interceptor 就可以获得这些信息。
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; // 获取处理当前请求的 handler 信息 System.out.println("handler 类：" + handlerMethod.getBeanType().getName()); System.out.println("handler 方法：" + handlerMethod.getMethod().getName()); MethodParameter[] methodParameters = handlerMethod.getMethodParameters(); for (MethodParameter methodParameter : methodParameters) { String parameterName = methodParameter.getParameterName(); // 只能获取参数的名称，不能获取到参数的值 //System.out.println("parameterName: " + parameterName); } // 把当前时间放入 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 { // 从 threadLocal 取出刚才存入的 startTime Long startTime = startTimeThreadLocal.get(); long endTime = System.currentTimeMillis(); System.out.println("time interceptor consume " + (endTime - startTime) + " ms"); System.out.println("time interceptor afterCompletion"); }} 注册 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); }} 启动服务器，在浏览器输入：http://localhost:8080/hello?name=tom
可以在控制台输出如下结果：
time filter starttime interceptor preHandlehandler 类：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 执行，再到真正执行 HelloController.sayHello() 方法。通过 interceptor 方法上的 handler 参数，我们就可以得到这个请求被哪个 Controller 以及哪个方法处理了。但是不能直接获取到这个方法上的参数值（在这里就是 HelloController.sayHello(String name) 方法参数 name 的值），通过 Aspect 就可以获取到。
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; } } 启动服务器，在浏览器输入：http://localhost:8080/hello?name=tom
可以在控制台输出如下结果：
time filter starttime interceptor preHandlehandler 类：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 先执行，再到 interceptor 执行，再到 aspect 执行，再到真正执行 HelloController.sayHello() 方法。
我们也获取到了 HelloController.sayHello(String name) 方法参数 name 的值。
请求拦截过程图
graph TDhttprequest-->filterfilter-->interceptorinterceptor-->aspectaspect-->controller
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