public class AuthenticationInterceptor implements HandlerInterceptor {
 @Autowired
 UserService userService;
 @Override
 public boolean preHandle(HttpServletRequest httpServletRequest,HttpServletResponse httpServletResponse,Object object) throws Exception {
 String token = httpServletRequest.getHeader("token");// 从 http 请求头中取出 token
 // 如果不是映射到方法直接通过
 if(!(object instanceof HandlerMethod)){
  return true;
 }
 HandlerMethod handlerMethod=(HandlerMethod)object;
 Method method=handlerMethod.getMethod();
 //检查是否有passtoken注释，有则跳过认证
 if (method.isAnnotationPresent(PassToken.class)) {
  PassToken passToken = method.getAnnotation(PassToken.class);
  if (passToken.required()) {
  return true;
  }
 }
 //检查有没有需要用户权限的注解
 if (method.isAnnotationPresent(UserLoginToken.class)) {
  UserLoginToken userLoginToken = method.getAnnotation(UserLoginToken.class);
  if (userLoginToken.required()) {
  // 执行认证
  if (token == null) {
   throw new RuntimeException("无token，请重新登录");
  }
  // 获取 token 中的 user id
  String userId;
  try {
   userId = JWT.decode(token).getAudience().get(0);
  } catch (JWTDecodeException j) {
   throw new RuntimeException("401");
  }
  User user = userService.findUserById(userId);
  if (user == null) {
   throw new RuntimeException("用户不存在，请重新登录");
  }
  // 验证 token
  JWTVerifier jwtVerifier = JWT.require(Algorithm.HMAC256(user.getPassword())).build();
  try {
   jwtVerifier.verify(token);
  } catch (JWTVerificationException e) {
   throw new RuntimeException("401");
  }
  return true;
  }
 }
 return true;
 }

 @Override
 public void postHandle(HttpServletRequest httpServletRequest,Object o,ModelAndView modelAndView) throws Exception {

 }
 @Override
 public void afterCompletion(HttpServletRequest httpServletRequest,Exception e) throws Exception {
 }

实现一个拦截器就需要实现HandlerInterceptor@H_301_10@接口

@Configuration
public class InterceptorConfig extends WebMvcConfigurerAdapter {
 @Override
 public void addInterceptors(InterceptorRegistry registry) {
 registry.addInterceptor(authenticationInterceptor())
  .addPathPatterns("/**"); // 拦截所有请求，通过判断是否有 @Loginrequired 注解 决定是否需要登录
 }
 @Bean
 public AuthenticationInterceptor authenticationInterceptor() {
 return new AuthenticationInterceptor();
 }
}

@Configuration
public class InterceptorConfig implements WebMvcConfigurer {
 @Override
 public void addInterceptors(InterceptorRegistry registry) {
 registry.addInterceptor(authenticationInterceptor())
  .addPathPatterns("/**");
 }
 @Bean
 public AuthenticationInterceptor authenticationInterceptor() {
 return new AuthenticationInterceptor();
 }
}

@RestController
@RequestMapping("api")
public class UserApi {
 @Autowired
 UserService userService;
 @Autowired
 TokenService tokenService;
 //登录
 @PostMapping("/login")
 public Object login(@RequestBody User user){
 JSONObject jsonObject=new JSONObject();
 User userForBase=userService.findByUsername(user);
 if(userForBase==null){
  jsonObject.put("message","登录失败,用户不存在");
  return jsonObject;
 }else {
  if (!userForBase.getPassword().equals(user.getPassword())){
  jsonObject.put("message",密码错误");
  return jsonObject;
  }else {
  String token = tokenService.getToken(userForBase);
  jsonObject.put("token",token);
  jsonObject.put("user",userForBase);
  return jsonObject;
  }
 }
 }
 @UserLoginToken
 @GetMapping("/getMessage")
 public String getMessage(){
 return "你已通过验证";
 }
}