RESTful API的拦截

场景：对RESTfulAPI作统一的处理，比如希望对所有的RESTfulAPI记录服务处理的时间。

一、过滤器Filter

可以拿到原始的http请求和响应的信息，
但是拿不到真正处理请求的那个方法的信息。

自定义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 request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        System.out.println("time filter start");
        long start = new Date().getTime();
        chain.doFilter(request, response);
        System.out.println("time filter耗时: "+(new Date().getTime()-start));
        System.out.println("time filter finish");
    }

    @Override
    public void destroy() {
        System.out.println("time filter destroy");
    }

}

控制台打印：

time filter init
time filter start
进入getInfo服务
time filter 耗时：0
time filter finish

在使用第三方过滤器时，需要通过web.xml配置；但对springboot来说，没有该配置文件

使用配置类：

@Configuration
public class WebConfig {
    
    @Bean
    public FilterRegistrationBean timeFiler() {
        FilterRegistrationBean registrationBean = new FilterRegistrationBean();
        
        TimeFilter timeFilter = new TimeFilter();
        
        registrationBean.setFilter(timeFilter);
        
        List<String> urls = new ArrayList<>();
        
        urls.add("/*");//所有路径都起作用
        registrationBean.setUrlPatterns(urls);
        return registrationBean;
    }
    
}

二、拦截器Interceptor

既可以拿到原始的http请求和响应，
也可以拿到真正处理请求的方法的信息，
但是拿不到具体方法被调用的时候的调用的参数的值。

使用Interceptor记录服务耗时

TimeInterceptor：

package com.hcx.web.interceptor;

import java.util.Date;

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

import org.springframework.stereotype.Component;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
@Component
public class TimeInterceptor implements HandlerInterceptor{

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        System.out.println("preHandle");
        
        System.out.println(((HandlerMethod)handler).getBean().getClass().getName());
        System.out.println(((HandlerMethod)handler).getMethod().getName());
        
        request.setAttribute("startTime", new Date().getTime());
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        System.out.println("postHandle");
        Long start = (Long) request.getAttribute("startTime");
        System.out.println("time interceptor耗时："+(new Date().getTime()-start));
    }

    //不管控制器方法成功还是失败，都会进入该方法
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        System.out.println("afterCompletion");
        Long start = (Long) request.getAttribute("startTime");
        System.out.println("time interceptor耗时："+(new Date().getTime()-start));
        System.out.println("ex is "+ex);
    }

}

配置：

@Configuration
public class WebConfig extends WebMvcConfigurerAdapter{
    
    @Autowired
    private TimeInterceptor timeInterceptor;
    
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(timeInterceptor);
    }
    
    @Bean
    public FilterRegistrationBean timeFiler() {
        FilterRegistrationBean registrationBean = new FilterRegistrationBean();
        
        TimeFilter timeFilter = new TimeFilter();
        
        registrationBean.setFilter(timeFilter);
        
        List<String> urls = new ArrayList<>();
        
        urls.add("/*");
        registrationBean.setUrlPatterns(urls);
        return registrationBean;
    }
    
}

运行结果：

time filter start
preHandle
com.hcx.web.controller.UserController$$EnhancerBySpringCGLIB$$ab2fe549
getInfo
进入getInfo服务
postHandle
time interceptor耗时：2
afterCompletion
time interceptor耗时：2
ex is null
time filter耗时: 4
time filter finish

如果方法抛出异常：

@GetMapping("/{id:\\d+}")
    @JsonView(User.UserDetailView.class)
    public User getInfo(@PathVariable String id) {
        throw new UserNotExistException(id);
//      System.out.println("进入getInfo服务");
//      User user = new User();
//      user.setUsername("tom");
//      return user;
    }

运行结果：没有了posthandler，ex在afterCompletion为空是因为异常处理器ControllerExceptionHandler把抛出去的异常处理了，没有传递到方法里。（即ControllerExceptionHandler该控制器是在afterCompletion之前执行的），除非抛出的异常没有被该异常处理器处理，比如runtimeException。

time filter init
time filter start
preHandle
com.hcx.web.controller.UserController$$EnhancerBySpringCGLIB$$68887b2a
getInfo
afterCompletion
time interceptor耗时：40
ex is null
time filter耗时: 49
time filter finish

局限：无法知道方法中的具体参数

三、切片Aspect

可以拿到方法被调用的时候传递进来的参数的值，
但是拿不到原始的http请求和响应的对象。

springaop.png

第一步：需要添加依赖：

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

第二步：编写切面类

@Aspect
@Component
public class TimeAspect {
    
    @Around("execution(* com.hcx.web.controller.UserController.*(..))")
    public Object handleControllerMethod(ProceedingJoinPoint pjp) throws Throwable {
        System.out.println("time aspect start");
        
        //方法参数的数组
        Object[] args = pjp.getArgs();
        for (Object arg : args) {
            System.out.println("arg is "+arg);
        }
        
        long start = new Date().getTime();
        
        Object object = pjp.proceed();
        System.out.println("time aspect 耗时："+(new Date().getTime() - start));
        
        System.out.println("time aspect end");
        return object;
    }
    
}

控制台打印：

time filter start
preHandle
com.hcx.web.controller.UserController$$EnhancerBySpringCGLIB$$ab2fe549
getInfo
time aspect start
arg is 1
进入getInfo服务
time aspect 耗时：0
time aspect end
postHandle
time interceptor耗时：2
afterCompletion
time interceptor耗时：2
ex is null
time filter耗时: 4
time filter finish

拦截执行顺序.png