SpringBoot如何添加拦截器

在web开发的过程中，为了实现登录权限验证，我们往往需要添加一个拦截器在用户的的请求到达controller层的时候实现登录验证，那么SpringBoot如何添加拦截器呢？

步骤如下：

1.继承WebMvcConfigureAdapter类，覆盖其addInterceptors接口,注册我们自定义的拦截器：

/**  *  * 注册拦截器  * Created by SYSTEM on 2017/8/16.  */  public class WebAppConfig extends WebMvcConfigurerAdapter {        @Override      public void addInterceptors(InterceptorRegistry registry) {          //注册自定义拦截器，添加拦截路径和排除拦截路径          registry.addInterceptor(new InterceptorConfig()).addPathPatterns("api/path/**").excludePathPatterns("api/path/login");      }  } 

2.实现HandlerInterceptor接口，重写接口中的三个方法：

public class InterceptorConfig  implements HandlerInterceptor{        private static final Logger log = LoggerFactory.getLogger(InterceptorConfig.class);        /**      * 进入controller层之前拦截请求      * @param httpServletRequest      * @param httpServletResponse      * @param o      * @return      * @throws Exception      */      @Override      public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {            log.info("---------------------开始进入请求地址拦截----------------------------");          HttpSession session = httpServletRequest.getSession();          if(!StringUtils.isEmpty(session.getAttribute("userName"))){              return true;          }          else{              PrintWriter printWriter = httpServletResponse.getWriter();              printWriter.write("{code:0,message:\"session is invalid,please login again!\"}");              return false;          }        }        @Override      public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {          log.info("--------------处理请求完成后视图渲染之前的处理操作---------------");      }        @Override      public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {          log.info("---------------视图渲染之后的操作-------------------------0");      }  }  

这样我们就可以在用户请求到达controller层实现登录拦截了，所有用户请求都会被拦截，在prehandle方法进行登录判断，返回true则验证通过，否则失败