在拦截器中添加对 Jwt Token 的验证，并处理在 Token 无效或过期时的情况。可以使用第三方库 jwt-decode 来验证 Token 是否过期，以下是示例代码：

import { Injectable } from '@angular/core';
import {
  HttpEvent,
  HttpHandler,
  HttpInterceptor,
  HttpRequest,
} from '@angular/common/http';
import { Observable } from 'rxjs';
import { tap } from 'rxjs/operators';
import * as jwt_decode from 'jwt-decode';

@Injectable()
export class TokenInterceptor implements HttpInterceptor {

  intercept(
    request: HttpRequest,
    next: HttpHandler
  ): Observable> {

    const JWT_TOKEN = 'your_token_here';
    const decodedToken: any = jwt_decode.default(JWT_TOKEN);

    if (decodedToken.exp < new Date().getTime() / 1000) {
      // Token 已过期，进行相关操作
    } else {
      request = request.clone({
        setHeaders: {
          Authorization: `Bearer ${JWT_TOKEN}`,
        },
      });
      return next.handle(request).pipe(
        tap(() => {
          // 请求成功操作
        }, (error) => {
          // 请求失败操作
        }));
    }
  }
}