From 9876071ce28e37782c592d43f41c0394bca214d3 Mon Sep 17 00:00:00 2001
From: chai2010 <chaishushan@gmail.com>
Date: Sun, 18 Feb 2018 03:27:46 +0800
Subject: [PATCH] =?UTF-8?q?=E6=9B=B4=E6=96=B0=E6=9C=8D=E5=8A=A1=E8=84=9A?=
 =?UTF-8?q?=E6=9C=AC,=20=E7=A6=81=E6=AD=A2=E6=9C=AC=E5=9C=B0=E6=96=87?=
 =?UTF-8?q?=E4=BB=B6=E7=BC=93=E5=AD=98?=
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Content-Transfer-Encoding: 8bit

---
 server.go | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

diff --git a/server.go b/server.go
index 252dcf3..0bf15bf 100644
--- a/server.go
+++ b/server.go
@@ -19,6 +19,7 @@ import (
 var (
 	flagRootDir     = flag.String("dir", ".", "root dir")
 	flagHttpAddr    = flag.String("http", ":8080", "HTTP service address")
+	flagNoCache     = flag.Bool("no-cache", true, "disable browser cache")
 	flagOpenBrowser = flag.Bool("openbrowser", true, "open browser automatically")
 )
 
@@ -47,7 +48,11 @@ func main() {
 		log.Printf("Hit CTRL-C to stop the server\n")
 	}()
 
-	log.Fatal(http.ListenAndServe(httpAddr, http.FileServer(http.Dir(*flagRootDir))))
+	mainHandler := http.FileServer(http.Dir(*flagRootDir))
+	if *flagNoCache {
+		mainHandler = NoCache(mainHandler)
+	}
+	log.Fatal(http.ListenAndServe(httpAddr, mainHandler))
 }
 
 // waitServer waits some time for the http Server to start
@@ -97,3 +102,41 @@ func startBrowser(url string) bool {
 	cmd := exec.Command(args[0], append(args[1:], url)...)
 	return cmd.Start() == nil
 }
+
+var epoch = time.Unix(0, 0).Format(time.RFC1123)
+
+var noCacheHeaders = map[string]string{
+	"Expires":         epoch,
+	"Cache-Control":   "no-cache, private, max-age=0",
+	"Pragma":          "no-cache",
+	"X-Accel-Expires": "0",
+}
+
+var etagHeaders = []string{
+	"ETag",
+	"If-Modified-Since",
+	"If-Match",
+	"If-None-Match",
+	"If-Range",
+	"If-Unmodified-Since",
+}
+
+func NoCache(h http.Handler) http.Handler {
+	fn := func(w http.ResponseWriter, r *http.Request) {
+		// Delete any ETag headers that may have been set
+		for _, v := range etagHeaders {
+			if r.Header.Get(v) != "" {
+				r.Header.Del(v)
+			}
+		}
+
+		// Set our NoCache headers
+		for k, v := range noCacheHeaders {
+			w.Header().Set(k, v)
+		}
+
+		h.ServeHTTP(w, r)
+	}
+
+	return http.HandlerFunc(fn)
+}