是否可以将预告片标头刷新到客户端？

Question

This results in 2 DATA frames being sent from a server:

func(w http.ResponseWriter, r *http.Request) {
    w.Write("foo")
    w.(http.Flusher).Flush()
    w.Write("bar")
    w.(http.Flusher).Flush()
}

This results in 1 HEADERS frames being sent from a server:

func(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Trailer:X", "a")
    w.(http.Flusher).Flush()
    w.Header().Set("Trailer:Y", "b")
    w.(http.Flusher).Flush()
}

Is there any way to get trailer frames sent as multiple HEADERS frames without using the framer api?

Answer 1

Usually Headers (or Trailers) can only be set before any response is sent to the client. After the first non-header data is sent, no further headers will be sent.

// Changing the header map after a call to WriteHeader (or
// Write) has no effect unless the modified headers are
// trailers.

https://golang.org/pkg/net/http/#ResponseWriter