拦截RESTful API并做相应处理的方式

⒈使用Filter（过滤器）

 package cn.coreqi.security.filter;

 import org.springframework.stereotype.Component;

 import javax.servlet.*;
 import java.io.IOException;
 import java.util.Date;

 @Component
 public class TimeFilter implements Filter {
     @Override
     public void init(FilterConfig filterConfig) throws ServletException {
         System.out.println("TimeFilterc初始化完成！");
     }

     @Override
     public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
         long start = new Date().getTime();
         filterChain.doFilter(servletRequest,servletResponse);
         System.out.println("执行方法所用时间：" + (new Date().getTime() - start));
     }

     @Override
     public void destroy() {
         System.out.println("TimeFilterc已释放！");
     }
 }

　　当然，如果是你自己写的Filter一般都会这样，别人的Filter就没有办法使用@Component注解了，那么你可以使用Web.xml，当然SpringBoot没有这个，可以使用SpringBoot独有的方式。

 package cn.coreqi.security.config;

 import cn.coreqi.security.filter.TimeFilter;
 import org.springframework.boot.web.servlet.FilterRegistrationBean;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;

 import java.util.ArrayList;
 import java.util.List;

 @Configuration
 public class WebConfig {
     @Bean
     public FilterRegistrationBean timeFilter(){
         FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
         filterRegistrationBean.setFilter(new TimeFilter());
         List<String> urls = new ArrayList<>();
         urls.add("/*");
         filterRegistrationBean.setUrlPatterns(urls);
         return filterRegistrationBean;
     }
 }

遗憾的是，Filter是Servlet提供的，SpringMVC的一些信息没有办法全部拿到，只能拿到request和response，没有办法拿到是那个控制器，那个方法处理的。这种情况下可以考虑Spring提供的Interceptor（拦截器）。

⒉使用Interceptor（拦截器）

 package cn.coreqi.security.interceptor;

 import org.springframework.stereotype.Component;
 import org.springframework.web.method.HandlerMethod;
 import org.springframework.web.servlet.HandlerInterceptor;
 import org.springframework.web.servlet.ModelAndView;

 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 @Component
 public class TimeInterceptor implements HandlerInterceptor {
     /**
      * 在控制器方法调用之前执行
      * @param request
      * @param response
      * @param handler   当前控制器方法
      * @return
      * @throws Exception
      */
     @Override
     public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
         System.out.println(((HandlerMethod) handler).getBean().getClass().getName());
         System.out.println(((HandlerMethod) handler).getMethod().getName());
         return true;
     }

     /**
      * 在控制器方法调用之后执行，如果控制器方法抛出了异常，那么该方法将不会被调用
      * @param request
      * @param response
      * @param handler
      * @param modelAndView
      * @throws Exception
      */
     @Override
     public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

     }

     /**
      * 无论控制器方法是否抛出异常，该方法始终会被调用
      * @param request
      * @param response
      * @param handler
      * @param ex
      * @throws Exception
      */
     @Override
     public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

     }
 }

 package cn.coreqi.security.config;

 import cn.coreqi.security.filter.TimeFilter;
 import cn.coreqi.security.interceptor.TimeInterceptor;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.web.servlet.FilterRegistrationBean;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

 import java.util.ArrayList;
 import java.util.List;

 @Configuration
 public class WebConfig implements WebMvcConfigurer {

     @Autowired
     private TimeInterceptor timeInterceptor;

     @Bean
     public FilterRegistrationBean timeFilter(){
         FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
         filterRegistrationBean.setFilter(new TimeFilter());
         List<String> urls = new ArrayList<>();
         urls.add("/*");
         filterRegistrationBean.setUrlPatterns(urls);
         return filterRegistrationBean;
     }

     @Override
     public void addInterceptors(InterceptorRegistry registry) {
         registry.addInterceptor(timeInterceptor);
     }
 }

拦截器可以拿到请求、响应、处理请求控制器方法的对象，但没法拿到处理请求方法参数的值。如果想要更进一步的拿到具体参数的值，那么就需要用到切片。

⒊使用Aspect（切片）

         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-aop</artifactId>
         </dependency>

 package cn.coreqi.security.aspect;

 import org.aspectj.lang.ProceedingJoinPoint;
 import org.aspectj.lang.annotation.Around;
 import org.aspectj.lang.annotation.Aspect;
 import org.springframework.stereotype.Component;

 @Aspect //声明当前类为切片类
 @Component  //让切片成为Spring容器中的一部分
 public class TimeAspect {

     /**
      * 第一个*代表任何返回值
      * cn.coreqi.security.controller.UserController.*   代表拦截该类（控制器）中的所有方法
      * (..)代表该方法可以有任意参数
      * @param pjp   表示当前所拦截的信息
      * @return
      */
     @Around("execution(* cn.coreqi.security.controller.UserController.*(..))")
     public Object handleControllerMethod(ProceedingJoinPoint pjp) throws Throwable {
         for (Object arg:pjp.getArgs()){ //遍历拦截方法的参数列表
             System.out.println("arg is :" + arg);
         }
         Object object = pjp.proceed();  //调用真正的方法
         return object;
     }
 }