Axios,fetch()将请求头设置为访问控制请求头,而不是单独的头

这是axios拦截器的代码:

addCaptchaHeaders(captcha, sgn, exp) {
    // remove the old captcha headers
    if (this.captchaHeadersInterceptor !== undefined) {
      this.removeCaptchaHeader();
    }
    // Sign new captcha headers
    this.captchaHeadersInterceptor = this.httpClient.interceptors.request.use(
      config => {
        // Add headers here
        config.headers.common._captcha = captcha;
        config.headers.common._sgn = sgn;
        config.headers.common._exp = exp;
        return config;
      },
      error => {
        // Do something with request error
        return Promise.reject(error);
      }
    );
  }

以下是飞行前请求的响应标头:

Access-Control-Allow-Headers: origin, content-type, accept, authorization, _captcha, _sgn, _exp
Content-Length: 0
Server: Jetty(9.3.24.v20180605)

以下是飞行前请求的请求头:

Accept: */*
Accept-Encoding: gzip, deflate, br
Accept-Language: en-US,en;q=0.9,sl;q=0.8
Access-Control-Request-Headers: _captcha,_exp,_sgn
Access-Control-Request-Method: GET
Connection: keep-alive
Host: localhost:8086
Origin: http://localhost:3000
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.92 Safari/537.36

飞行前请求之后的实际请求的标头是相同的。所以呢 Access-Control-Request-Headers: _captcha,_exp,_sgn 而不是自定义请求头。

以为是axios配置问题,我使用fetch发出了相同的请求:

fetch(
      "http://localhost:8086/podatki/parcela/search?parcela=1727&count=50&offset=0",
      {
        method: "GET",
        headers: {
          _captcha: res,
          _sgn: sgn,
          _exp: exp
        }
      }
    );

结果是一样的。

这是浏览器服务器通信的问题吗?如果是的话,响应头中是否缺少一些内容?

对邮递员做同样的请求也行。