使用切片拦截REST服务 Filter Interceptor Aspect

ゝ一纸荒年。 2022-05-10 03:33 187阅读 0赞

## 拦截的方法 ##

1.  过滤器 Filter 初始化 销毁 doFilter处理逻辑
2.  拦截器 Interceptor 调用之前 控制器 调用之后 最终调用
3.  切片 Aspect

## 过滤器 ##

@Component
    public class TimeFilter implements Filter {
    
    	@Override
    	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
    			throws IOException, ServletException {
    		System.out.println("time filter start"); //在执行 过滤
    		long start = new Date().getTime();
    		chain.doFilter(request, response); //放行到下一个过滤器，过滤器执行完，去执行action流程
    		System.out.println("time filter 耗时:"+ (new Date().getTime() - start));//流程执行完毕，打印时间
    		System.out.println("time filter finish"); //打印完成
    	}
    
    	@Override
    	public void init(FilterConfig arg0) throws ServletException {
    		System.out.println("time filter init"); //程序启动，执行初始化
    	}
    		@Override
    	public void destroy() {
    		System.out.println("time filter destroy");
    	}
    
    }

### 不用Component 配置 bean ###

@Configuration //期初 不用继承 ，继承了可以添加拦截器
    public class WebConfig extends WebMvcConfigurerAdapter {
    	@SuppressWarnings("unused")
    	@Autowired
    	private TimeInterceptor timeInterceptor;
    	
    	@Override
    	public void addInterceptors(InterceptorRegistry registry) {
    //		registry.addInterceptor(timeInterceptor);
    	}
    	
    //	@Bean
    	public FilterRegistrationBean timeFilter() {
    		FilterRegistrationBean registrationBean = new FilterRegistrationBean();
    		TimeFilter timeFilter = new TimeFilter();
    		registrationBean.setFilter(timeFilter);
    		List<String> urls = new ArrayList<>();
    		urls.add("/*"); //自定义URL
    		registrationBean.setUrlPatterns(urls);
    		return registrationBean;
    	}
    }

> 缺点：是有哪个Action来处理的，filter是不知道的。filter是j2EE，resultController注解是mvc的  
> 解决用 Interceptor(Spring框架提供的)

## Interceptor ##

@Component //需要继承 HandlerInterceptor
    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; //preHandle 必须返回true 才能继续
    	}
    
    	@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));
    
    	}
    	@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);
    //@ControllerAdvice 
    public class ControllerExceptionHandler //控制器的异常处理器 在interceptor之前
    //拦截器会拦截所有的控制器
    	}
    
    }

### 之后还需要添加到interceptor中 才能用 ###

@Configuration
    public class WebConfig extends WebMvcConfigurerAdapter {
    	@SuppressWarnings("unused")
    	@Autowired
    	private TimeInterceptor timeInterceptor;
    	@Override
    	public void addInterceptors(InterceptorRegistry registry) {
    //		registry.addInterceptor(timeInterceptor);
    	}

> 拦截器可以拿到 请求 响应 以及处理方法的对象（action）  
> 缺点 ，无法拿到 方法的参数 （源码组model的代码是在执行的下面）  
> 解决 用切片 Aspect

## 切片 Aspect ##

![在这里插入图片描述][70]

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

@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;
    	}
    }

> 切片拿不到原始的http请求和响应

## 拦截顺序 ##

![在这里插入图片描述][70 1]

> 出了异常，最先捕获异常的是 Aspect ，之后有Advice 异常处理器 处理 ，如果继续抛，继续往上  
> 不出 异常 没有ControllerAdvice

@ControllerAdvice
    public class ControllerExceptionHandler {
    	@ExceptionHandler(UserNotExistException.class)
    	@ResponseBody
    	@ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
    	public Map<String, Object> handleUserNotExistException(UserNotExistException ex) {
    		Map<String, Object> result = new HashMap<>();
    		result.put("id", ex.getId());
    		result.put("message", ex.getMessage());
    		return result;
    	}
    }

[70]: /images/20220510/194cef69ad4849be9dd01e43fadb387c.png
[70 1]: /images/20220510/a1519e5451e44b388ba71d9769e80c86.png