springboot下使用过滤器,拦截器,切片

1 Filter的使用
1)第一种使用方式：编写class类实现filter并使用@Component即可

@Component
public class TimeFilter implements Filter {

   /* (non-Javadoc)
    * @see javax.servlet.Filter#destroy()
    */
   @Override
   public void destroy() {
      System.out.println("time filter destroy");
   }

   /* (non-Javadoc)
    * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)
    */
   @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");
   }

   /* (non-Javadoc)
    * @see javax.servlet.Filter#init(javax.servlet.FilterConfig)
    */
   @Override
   public void init(FilterConfig arg0) throws ServletException {
      System.out.println("time filter init");
   }

}

2)第二种 使用第三方filter类，如将TimeFilter当作第三方filter使用（该种方式可以配置拦截url）

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

2 拦截器的使用
1)编写拦截器

@Component
public class TimeInterceptor implements HandlerInterceptor {

   /*
    *执行控制器方法前执行的方法
    */
   @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;
   }
   /*
    *执行控制器方法后执行的方法，抛异常后不会进入
    */
   @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));

   }
   /*
    *执行控制器方法后执行的方法，抛异常后也会进入
    */
   @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);

   }
}

2)配置拦截器

@Configuration
public class WebConfig extends WebMvcConfigurerAdapter {
   
   @SuppressWarnings("unused")
   @Autowired
   private TimeInterceptor timeInterceptor;

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

3 切片的使用
1）添加依赖

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

2）编写切片类

@Aspect
@Component
public class TimeAspect {
   @Around("execution(* com.imooc.web.controller.UserController.*(..))")
   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 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;
   }
}

3）切片的相关注解
@Before @After @AfterThrowing 和拦截器相对应
@Around包含了以上三个注解的功能
4）切片表达式的使用，查看springframe文档，11章有详细介绍

4 过滤器，拦截器，切片的区别
过滤器只能拿到http请求的请求和响应，并从其中拿到相应的参数，但是请求是由哪个控制器和哪个方法来处理的过滤器是无法获取的
拦截器，可以拿到http请求的请求和响应，也可以拿到请求是由哪个方法和控制器来处理的，但是无法拿到参数的值
切片,可以拿到当前拦截方法的信息,但是在拿不到它的原始的http请求与相应的对象。

5 SpringAop简介

6 拦截层级