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;
    }
}