我嘗試發布一本包含預訂數據的字典。但是 chrome 記錄了這個錯誤：Access to XMLHttpRequest at 'http://localhost:8080/reservations' from origin 'http://localhost:4200' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.這很奇怪，因為我可以發布圖像、視頻、html 內容，因為我@CrossOrigin在控制器上方放置了注釋。但是對于這個特定的帖子請求，它似乎不起作用。休息控制器：@CrossOrigin(origins="http://localhost:4200",        maxAge=2000,allowedHeaders="header1,header2",        exposedHeaders="header1",allowCredentials= "false")@RestControllerpublic class ReservationsController {    private ReservationDao dao;    @Autowired    public ReservationsController(ReservationDao dao) {        this.dao = dao;    }    @PostMapping("/reservations")    public Map<String, String> bookReservation(@RequestBody Map<String, String> reservation) {        System.out.println(reservation);        return null;    }}angular api bookReservation方法： bookReservation(data) {    console.log(data);    const result = this.http.post(this.apiUrl + 'reservations', data).subscribe(      (val) => {        console.log('POST call succesful value returned in body',          val);      },      response => {        console.log('POST call in error', response);      },      () => {        console.log('The POST observable is now completed');      });    console.log(result);  }