Three interceptors in spring

Filter

Create a new TimeFilter

@ Component

Public class TimeFilter implements Filter {@ Overridebr/ > @ Override

System.out.println ("time filter init")

}

Overridepublic 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");} @ Overridepublic void destroy () {System.out.println ("time filter init");}

}

Start the server and enter: http://localhost:8080/hello?name=tom in the browser

You can output the following results in the console:

Time filter start

Name: tom

Time filter consume 3 ms

Time filter end

As you can see, filter executes first, and then actually executes the HelloController.sayHello () method.

As can be seen from the parameters of the TimeFilter.doFilter (ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) method, we can only get the original request and response objects, not which Controller and which method the request was processed, and we can get this information using Interceptor.

Interceptor

Create a new TimeInterceptor

@ Component

Public class TimeInterceptor extends HandlerInterceptorAdapter {

Private final NamedThreadLocal 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

/ / get the handler information that processes the current request

System.out.println ("handler class:" + handlerMethod.getBeanType () .getName ())

System.out.println ("handler method:" + handlerMethod.getMethod () .getName ())

MethodParameter [] methodParameters = handlerMethod.getMethodParameters ()

For (MethodParameter methodParameter: methodParameters) {

String parameterName = methodParameter.getParameterName ()

/ / you can only get the name of the parameter, not the value of the parameter.

/ / System.out.println ("parameterName:" + parameterName)

}

/ / put the current time into 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 {

/ / withdraw the startTime you just saved from threadLocal

Long startTime = startTimeThreadLocal.get ()

Long endTime = System.currentTimeMillis ()

System.out.println ("time interceptor consume" + (endTime-startTime) + "ms"); System.out.println ("time interceptor afterCompletion")

}

}

Register for TimeInterceptor

Inject TimeInterceptor into the spring container

@ Configuration

Public class WebConfig extends WebMvcConfigurerAdapter {

@ Autowiredprivate TimeInterceptor timeInterceptor;@Overridepublic void addInterceptors (InterceptorRegistry registry) {registry.addInterceptor (timeInterceptor);}

}

Start the server and enter: http://localhost:8080/hello?name=tom in the browser

You can output the following results in the console:

Time filter start

Time interceptor preHandle

Handler class: com.nextyu.demo.web.controller.HelloController

Handler method: sayHello

Name: tom

Time interceptor postHandle

Time interceptor consume 40 ms

Time interceptor afterCompletion

Time filter consume 51 ms

Time filter end

As you can see, filter executes before interceptor, and then it actually executes the HelloController.sayHello () method. Through the handler parameter on the interceptor method, we can see which Controller and which method the request was processed by. However, the parameter value on this method cannot be obtained directly (in this case, the value of the parameter name of the HelloController.sayHello (String name) method), it can be obtained through Aspect.

Aspcet

Aspcet

Create a new TimeAspect

@ Aspect@Componentbr/ > @ Component

@ 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;}

}

Start the server and enter: http://localhost:8080/hello?name=tom in the browser

You can output the following results in the console:

Time filter start

Time interceptor preHandle

Handler class: com.nextyu.demo.web.controller.HelloController

Handler method: sayHello

Time aspect start

Arg is tom

Name: tom

Time aspect consume 0 ms

Time aspect end

Time interceptor postHandle

Time interceptor consume 2 ms

Time interceptor afterCompletion

Time filter consume 4 ms

Time filter end

As you can see, filter executes first, then to interceptor, then to aspect, and then to the actual execution of the HelloController.sayHello () method.

We also get the value of the HelloController.sayHello (String name) method parameter name.

Request interception process diagram

Graph TD

Httprequest-- > filter

Filter-- > interceptor

Interceptor-- > aspect

Aspect-- > controller