一、编写一个拦截器类

public class LoginInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("进入拦截器。。。。");
        return true;
    }
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}

二、写一个配置类使拦截器起作用

@Configuration
public class WebConfig extends WebMvcConfigurationSupport {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
       //需要拦截路径
        String[] addPathPatterns = {
                "/**"
        };
        //不需要拦截路径
        String[] excludePathPatterns = {
                "/config"
        };
        //注册登录拦截器
        registry.addInterceptor(new LoginInterceptor()).addPathPatterns(addPathPatterns).excludePathPatterns(excludePathPatterns);
    }
}