问检查go服务器中是否劫持了http连接。

EN

func handler(w http.ResponsWriter, r *http.Request) {
    defer reply(w, r, L)() //L is a Logger
    //do things...
}

func reply(w http.ResponseWriter, r *http.Request, log Logger) func() {
    cid := []byte{0, 0, 0, 0}
    if log != nil {
        rand.Read(cid)
        log.Debug("[%x] %s %s", cid, r.Method, r.URL.String())
    }
    entry := time.Now()
    return func() {
        if log != nil {
            defer log.Debug("[%x] elapsed %d millis", cid, time.Since(entry).Milliseconds())
        }
        _, err := w.Write(nil)
        if err == http.ErrHijacked {
            return //API is a WEBSOCKET entry point, do nothing
        }
        //handle common output logic for normal HTTP APIs...
    }
}

// ErrHijacked is returned by ResponseWriter.Write calls when
// the underlying connection has been hijacked using the
// Hijacker interface. A zero-byte write on a hijacked
// connection will return ErrHijacked without any other side
// effects.
ErrHijacked = errors.New("http: connection has been hijacked")

// Write writes the data to the connection as part of an HTTP reply.
//
// If WriteHeader has not yet been called, Write calls
// WriteHeader(http.StatusOK) before writing the data. If the Header
// does not contain a Content-Type line, Write adds a Content-Type set
// to the result of passing the initial 512 bytes of written data to
// ...
Write([]byte) (int, error)