映射角头http方法响应

Question

如何使用head http方法从请求中检索响应标头？

func SocketClient() {
    conn, err := net.Dial("tcp", ":9000")
    if err != nil {
        log.Fatal(err)
    }
    defer conn.Close()

    serverScan := bufio.NewScanner(conn)
    inputScan := bufio.NewScanner(os.Stdin)


    serverCh := ReadFully(serverScan)
    inputCh := ReadFully(inputScan)


    // create a wait group, this stops the SocketClient 
    // method from exiting until the workers are done.
    var wg sync.WaitGroup
    wg.Add(2)

    go func() {
        defer wg.Done()
        for v := range inputCh {
            _, _ = conn.Write([]byte(v))
        }
    }()

    go func() {
        defer wg.Done()
        for v := range serverCh {
            fmt.Printf("Received: %s\n", v)
        }
    }()

    wg.Wait()
}

事件始终为空

解决方案

getCount(): Observable<number> {
    return this.http.head(`${this.baseUrl}`)
      .pipe(
        map((event: any) => {
          if (event instanceof HttpResponse) {
            return +event.headers.get('header-name');
          }
          return 0;
        }),
      );
  }