Filter
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新建 TimeFilter
重慶分公司
重慶分公司
@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");
}
}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(jié)果：
time filter start
name: tom
time filter consume 3 ms
time filter end
可以看到，filter 先執(zhí)行，再到真正執(zhí)行 HelloController.sayHello() 方法。
通過 TimeFilter.doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) 方法的參數(shù)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
@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;
// 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(shù)的名稱，不能獲取到參數(shù)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
@Configuration
public 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(jié)果：
time filter start time interceptor preHandle handler 類：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
可以看到，filter 先于 interceptor 執(zhí)行，再到真正執(zhí)行 HelloController.sayHello() 方法。通過 interceptor 方法上的 handler 參數(shù)，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(shù)值（在這里就是 HelloController.sayHello(String name) 方法參數(shù) name 的值），通過 Aspect 就可以獲取到。
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;
}
}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(jié)果：
time filter start time interceptor preHandle handler 類：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
可以看到，filter 先執(zhí)行，再到 interceptor 執(zhí)行，再到 aspect 執(zhí)行，再到真正執(zhí)行 HelloController.sayHello() 方法。
我們也獲取到了 HelloController.sayHello(String name) 方法參數(shù) name 的值。
請求攔截過程圖
graph TD httprequest-->filter filter-->interceptor interceptor-->aspect aspect-->controller
