springboot 错误记录

Posted 2021-01-04 yangfei969

1.拦截器中handler cannot be cast to HandlerMethod

java.lang.ClassCastException: org.springframework.web.servlet.resource.ResourceHttpRequestHandler cannot be cast to org.springframework.web.method.HandlerMethod

 

public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object handler) throws Exception {
            //此处报错
            HandlerMethod handlerMethod = (HandlerMethod) handler;
    }

原因就在于，spring boot 2.0对静态资源也进行了拦截，当拦截器拦截到请求之后，但controller里并没有对应的请求时，该请求会被当成是对静态资源的请求。此时的handler就是 ResourceHttpRequestHandler，就会抛出上述错误。

解决办法：

1.拦截器那里排除静态资源的请求路径

registry.addInterceptor(new MyInterceptor()).addPathPatterns("/xx/**")
                .excludePathPatterns("/xx/**");

2. instanceof关键字进行判断。

if(handler instanceof ResourceHttpRequestHandler) {
                logger.info("---------ResourceHttpRequestHandler-------" + handler.toString() + "------------");
            }else if(handler instanceof HandlerMethod){
                logger.info("--------HandlerMethod--------" + handler.toString() + "------------");
            }