springboot下使用过滤器,拦截器,切片

小咪咪 2022-02-25 05:12 396阅读 0赞

**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**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L211c2lfbQ_size_16_color_FFFFFF_t_70]  
**6 拦截层级**  
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