modified as astaxie reviews

https://github.com/astaxie/beego/pull/1376

config.go

@@ -529,7 +529,6 @@ func ParseConfig() (err error) {
 			if ext == "" {
 				continue
 			}
-			ext = strings.ToLower(ext)
 			if !strings.HasPrefix(ext, ".") {
 				ext = "." + ext
 			}

memzipfile.go

@@ -206,9 +206,9 @@ func getAcceptEncodingZip(r *http.Request) string {
 	ss = strings.ToLower(ss)
 	if strings.Contains(ss, "gzip") {
 		return "gzip"
-	}
-	if strings.Contains(ss, "deflate") {
+	} else if strings.Contains(ss, "deflate") {
 		return "deflate"
-	}
+	} else {
 		return ""
+	}
 }

staticfile.go

@@ -96,9 +96,8 @@ func serverStaticRouter(ctx *context.Context) {
 			}
 
 			isStaticFileToCompress := false
-			lowerFileName := strings.ToLower(filePath)
 			for _, statExtension := range StaticExtensionsToGzip {
-				if strings.HasSuffix(lowerFileName, statExtension) {
+				if strings.HasSuffix(strings.ToLower(filePath), strings.ToLower(statExtension)) {
 					isStaticFileToCompress = true
 					break
 				}