请教个问题：一次调用为何被执行了两三次？

日志 ``` [Debug] 2016-05-28 19:47:10.812379321 +0800 CST get file handler: GET /16,2019fe6c23 [Debug] 2016-05-28 19:47:10.967188428 +0800 CST get file handler: GET /16,2019fe6c23 ``` 简要代码 ``` http.HandleFunc("/submit", submitHandler) http.HandleFunc("/", getFileHandler) e := http.ListenAndServe(listeningAddress, nil) if e != nil { log.Error("Weeder Proxy startup error: ", e) } ``` getFileHandler 方法中通过http.Get(url) 读取了另外一个网址的图片，然后返回给当前调用的客户端， 奇怪的是从日志看为什么每次调用都会被执行两三次？ 请问有人遇到过这个问题么？ 先谢谢各位了。 源码 ``` package main import ( "bytes" log "fmt" "io" "io/ioutil" "net/http" ) func main() { http.HandleFunc("/submit", submitHandler) http.HandleFunc("/", getFileHandler) e := http.ListenAndServe("0.0.0.0:9330", nil) if e != nil { log.Println("Weeder Proxy startup error: ", e) } } func submitHandler(w http.ResponseWriter, r *http.Request) { log.Println("submit handler: ", r.Method, " ", r.RequestURI) } func getFileHandler(w http.ResponseWriter, r *http.Request) { log.Println("get file handler: ", r.Method, " ", r.RequestURI) err := download("https://www.baidu.com/img/bd_logo1.png", w, r) // var err error = nil if err != nil { log.Println("download: ", err) w.WriteHeader(http.StatusBadRequest) w.Write([]byte("{\"error\":\"Can't get the file!\"}")) } else { log.Println("get file handler: ", r.Method, " ", r.RequestURI, "success.") } } func download(url string, w http.ResponseWriter, r *http.Request) error { defer func() { if r := recover(); r != nil { log.Println("download: ", r) } }() resp, err := http.Get(url) if err != nil { return err } defer resp.Body.Close() /** * ioutil.ReadAll(resp.Body) * 会将文件整个读取到内存中后才返回,如果文件较大或并发访问量较大,需要注意 */ pix, err := ioutil.ReadAll(resp.Body) if err != nil { return err } return writeResponseContent(bytes.NewReader(pix), resp, w, r) // pix, err := ioutil.ReadFile("/apps/gopath/src/qianbao.com/weeder/explain-it-simply.jpg") // if err != nil { // return err // } // var resp *http.Response = nil // return ps.writeResponseContent(bytes.NewReader(pix), int64(len(pix)), resp, w, r) } func writeResponseContent( rs io.ReadSeeker, resp *http.Response, w http.ResponseWriter, r *http.Request) error { var e error = nil mimeType := "" if resp != nil { mimeType = resp.Header.Get("Content-Type") w.Header().Set("Content-Type", mimeType) w.Header().Set("Content-Disposition", resp.Header.Get("Content-Disposition")) w.Header().Set("Content-Length", resp.Header.Get("Content-Length")) } w.Header().Set("Accept-Ranges", "bytes") rangeReq := r.Header.Get("Range") if rangeReq == "" { _, e = io.Copy(w, rs) return e } return e } ```