每当需要返回时io.ReadCloser，同时确保Close()可用，则可以使用NopCloser来构建这样的ReaderCloser。

您可以在此gorest分支中看到一个示例，在util.go

//Marshals the data in interface i into a byte slice, using the Marhaller/Unmarshaller specified in mime.
//The Marhaller/Unmarshaller must have been registered before using gorest.RegisterMarshaller
func InterfaceToBytes(i interface{}, mime string) (io.ReadCloser, error) {
    v := reflect.ValueOf(i)
    if v.Kind() == reflect.Ptr {
        v = v.Elem()
    }
    switch v.Kind() {
    case reflect.Bool:
        x := v.Bool()
        if x {
            return ioutil.NopCloser(bytes.NewBuffer([]byte("true"))), nil
        }