一.登录校验成功放行

 /**
 * 进⼊到controller之前的⽅法
 * @param request
 * @param response
 * @param handler
 * @return
 * @throws Exception
 */
@Override
public boolean preHandle(HttpServletRequest request,HttpServletResponse response, Object handler) throws Exception {
 try {
 String accesToken = request.getHeader("token");
 if (accesToken == null) {
 accesToken = request.getParameter("token");
 }
 if (StringUtils.isNotBlank(accesToken)) {
 Claims claims = JWTUtils.checkJWT(accesToken);
 if (claims == null) {
 //告诉登录过期，重新登录
 sendJsonMessage(response, JsonData.buildError("登录过期，重新登录"));
 return false;
 }
 Integer id = (Integer) claims.get("id");
 String name = (String) claims.get("name");
 request.setAttribute("user_id", id);
 request.setAttribute("name", name);
 return true;
 }
 }catch (Exception e){}
 sendJsonMessage(response, JsonData.buildError("登录过期，重新登录"));
 return false;
 }

二.登录不成功返回json数据

 /**
 * 响应json数据给前端
 * @param response
第2集 ⼩滴课堂实战之loginInterceptor注册和放⾏路径
简介：loginInterceptor 拦截器注册和路径校验配置
继承 WebMvcConfigurer
配置拦截路径和放⾏路径
 * @param obj
 */
public static void sendJsonMessage(HttpServletResponse response,
Object obj){
 try{
 ObjectMapper objectMapper = new ObjectMapper();
 response.setContentType("application/json; charset=utf-
8");
 PrintWriter writer = response.getWriter();
 writer.print(objectMapper.writeValueAsString(obj));
 writer.close();
 response.flushBuffer();
 }catch (Exception e){
 e.printStackTrace();
 }
 }

注解：返回给前端的数据需要序列化，运用objectMapper序列化参数。

三.拦截器注册和路径校验配置

/**
 * 拦截器配置
 *
 * 不⽤权限可以访问url /api/v1/pub/
 * 要登录可以访问url /api/v1/pri/
 */
@Configuration
public class InterceptorConfig implements WebMvcConfigurer {
 @Bean
 LoginInterceptor loginInterceptor(){
 return new LoginInterceptor();
 }
 @Override
 public void addInterceptors(InterceptorRegistry registry) {
 //拦截全部
 
registry.addInterceptor(loginInterceptor()).addPathPatterns("/api/v1/pri/*/*/*
*")
 //不拦截哪些路径 斜杠⼀定要加
 
.excludePathPatterns("/api/v1/pri/user/login","/api/v1/pri/user/register");
 WebMvcConfigurer.super.addInterceptors(registry);
 }
}

注解：实现WebMvcConfigure接口重写addInterceptors方法，添加拦截路径时需注意路径的写法，excludePathPatterns("/api/v1/pri/user/login","/api/v1/pri/user/register")指定不需要拦截的路径。 最后要调用父类的addInterceptors方法提交注册器。