如何判断nethttp的ResponseWriter.Write（）是否已被调用？

http.ResponseWriter

type MyResponseWriter struct {    http.ResponseWriter    WroteHeader bool}func (w *MyResponseWriter) Write(b []byte) (int, error) {    w.WroteHeader = true    return w.ResponseWriter.Write(b)}func (w *MyResponseWriter) WriteHeader(pre int) {    w.WroteHeader = true    w.ResponseWriter.WriteHeader(pre)}

在您的处理程序中：

//...if w, ok := w.(*MyResponseWriter); ok && w.WroteHeader {    log.Println("Already wrote, skipping")    return}

编辑： 另一件事要考虑。在大多数情况下，如果您具有处理程序的“链”，则意味着在处理程序内部调用处理程序。所以如果你有类似的东西

type Handler1 struct { http.Handler }type Handler2 struct { http.Handler }type Handler3 struct { http.Handler }var MyHandler http.Handler = Handler1{Handler2{Handler3{h}}}

只要每个那些调用内部处理程序 ，因为他们与做的最后一件事

w

r

w

r

func (h Handler2) ServeHTTP(w http.ResponseWriter, r *http.Request) {    if somethingBadHappened() {        w.WriteHeader(http.StatusInternalServerError)        return    }    h.ServeHTTP(w, r) // Not called if somethingBadHappened().}