Golang JSON封送将emoji转换为问号(Golang JSON marshaling converts emoji to question mark)

I was eventually able to find a workaround. Previously I was marshaling the JSON into a []byte and then calling w.Write(jsonBytes) on my http.ResponseWriter. By casting the bytes to a string, writing the appropriate content type header and using io.WriteString instead I was able to prevent the mangling. Here is my code:

returnJSON, error := json.Marshal(value)
if error != nil { Error(w, error); return }
w.Header().Set("Content-Type", "application/json; charset=utf-8")
io.WriteString(w, string(returnJSON))