要實現自定義HandlerInterceptor 。通過 WebMvcConfigurer 的實現類屬性注入，完成springboot自定義攔截

自定義一個攔截器；

package com.baidu.interceptor;
/**
 * @auther SyntacticSugar
 * @data 2018/11/2 0002下午 2:51
 */
public class LoginInterceptor implements HandlerInterceptor {
    private Logger logger=LoggerFactory.getLogger((LoginInterceptor.
 
class));
    //  配置一個 interceptor
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
            logger.debug("preHandle is  running");
        return true;
    }
    @Override
    public void postHandle(HttpServletRequest request,
 
 HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        logger.debug("postHandle is  running");
    }
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        logger.
 
debug("afterCompletion is  running");
    }
}

注入自定義的攔截器；

package com.baidu.config;
/**
 * @auther SyntacticSugar
 * @data 2018/11/2 0002下午 2:49
 */
@Configuration
public class MvcConfig implements WebMvcConfigurer {
        //  注入攔截器
    @Bean
    public LoginInterceptor getLoginInterceptor(){
        return  new LoginInterceptor();
    }
        //   把自定義的攔截器新增到mvc 配置中
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(this.getLoginInterceptor()).addPathPatterns("/**");
    }
}

*訪問web伺服器; *

HandlerInterceptor 檢視原始碼如下：

(1) 第一個preHandle

	default boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
			throws Exception {
		return true;
	}

在HandlerMapping之後執行,HandlerAdapter之前，返回結果 true

(2) 第二個postHandle

	default void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
			@Nullable ModelAndView modelAndView) throws Exception {
	}

在HandlerAdapter 之後，在DispatcherServlet之前呼叫，並且通過ModelAndView 檢視解析器解析 檢視 model object；

(3) 第三個afterCompletion

default void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler,
			@Nullable Exception ex) throws Exception {
	}

request處理完成之後，回撥函式，獲取解析檢視；