spring mvc HandlerInterceptor拦截器

柔光的暖阳◎ 2022-06-02 01:18 186阅读 0赞

\#spring mvc HandlerInterceptor拦截器

\#\#spring-mvc.xml 配置  
在 spring-mvc.xml 文件下增加

<mvc:interceptors>
        	<!—拦截器 拦截器执行顺序:先执行后定义的，排在第一位的最后执行—>    
        	<mvc:interceptor>
                <mvc:mapping path = ““ />//拦截的请求 
                <bean class = “" />//拦截处理器的全限定名
        	</mvc:interceptor>
    
        	<mvc:interceptor>
           	 <mvc:mapping path = “” /> //拦截的请求       
            	<bean  class = “” >//拦截处理器的权限定名
        	</mvc:interceptor>
    
    	</mvc:interceptors>

\#\#定义处理器

拦截处理器 实现 HandlerInterceptor 接口

需要重写三个方法

-   public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, object o ) throws Exception   
      // 请求预处理   在请求处理之前进行调用 返回true 才会进入处理器
    
    -    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse,Object o,ModelAndView modelAndView) throws Exception     
      // 将在请求处理之后，DispatcherServlet进行视图返回渲染之前进行调用
    
    
    -   public void afterCompletion(HttpServletRequest httpServletRequest, HttpServleResponse httpServletResponse,Object o , Exception e) throws  Exception 
    
       // 整个请求结束之后

\#\#处理器代码

**处理器：对接口处理进行计时，如果大于200ms则报警，如果有异常则报警**

public class ApiResponseInterceptor  extends BaseService implements HandlerInterceptor {
    
        private static final ThreadLocal<Long> startTimeThreadLocal =
                new NamedThreadLocal<Long>("ThreadLocal StartTime");
    
        @Override
        public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
            long beginTime = System.currentTimeMillis();//1、开始时间
            startTimeThreadLocal.set(beginTime);      //线程绑定变量（该数据只有当前请求的线程可见）
            return true;
        }
    
        //TODO   500 报警
        @Override
        public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
                logger.error("api通过处理");
        }
    
            //TODO 判断时间
        @Override
        public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
    
            long beginTime = startTimeThreadLocal.get();//得到线程绑定的局部变量（开始时间）
            long endTime = System.currentTimeMillis();     //2、结束时间
            long handTime = endTime -beginTime;//时间大于200ms的接口报警
            if(handTime > 200){
                //发消息到报警群
                String uri =  httpServletRequest.getRequestURI();
    
                logger.info(uri);
                //线程异步处理
                ThreadService service =  SpringContextHolder.getBean(ThreadService.class);
               // service.sendMessage(uri,handTime);
            }
                HandlerMethod method = (HandlerMethod)o;
    
    
             logger.info(method.getReturnType().getParameterName());
    
           //  HttpServletResponseCopier copier = new HttpServletResponseCopier(httpServletResponse);
            //copier.getCopy();
            //如果出现异常，则进行报警
            int status = httpServletResponse.getStatus();
            if(status == 500){
                //使用线程发送消息到钉钉
                ThreadService service =  SpringContextHolder.getBean(ThreadService.class);
                service.sendMessageHttpFail(httpServletRequest.getRequestURI());
            }
    
        }
    }

由于计时需要在 preHandlehe 和 postHandle 中进行计时，需要声明类变量。由于我们定义的是static，如果需要每个线程都的计时是独立的，那么我们需要使用ThreadLocal。

**ThreadLocal 会对对每个线程提供一个变量的副本，变量在线程之间是不共享的（注意是不共享的，）。**

> This class provides thread-local variables. These variables differ from

*  their normal counterparts in that each thread that accesses one (via its
 *  \{@code get\} or \{@code set\} method) has its own, independently initialized
 *  copy of the variable. \{@code ThreadLocal\} instances are typically private
 *  static fields in classes that wish to associate state with a thread (e.g.,
 *  a user ID or Transaction ID).