spring里的三大拦截器

Filter

新建 TimeFilter

@Component

public 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

Interceptor

新建 TimeInterceptor

@Component

public 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

@Configuration

public 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 start

time interceptor preHandle

handler 类：com.nextyu.demo.web.controller.HelloController

handler 方法：sayHello

name: tom

time interceptor postHandle

time interceptor consume 40 ms

time interceptor afterCompletion

time filter consume 51 ms

time filter end

Aspcet

新建 TimeAspect

@Aspect

@Component

public 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 start

time interceptor preHandle

handler 类：com.nextyu.demo.web.controller.HelloController

handler 方法：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

请求拦截过程图

graph TD

httprequest-->filter

filter-->interceptor

interceptor-->aspect

aspect-->controller