Merge pull request #3345 from dingyuanhong/develop

fix / can use dynamic directory

staticfile.go

@@ -178,7 +178,7 @@ func searchFile(ctx *context.Context) (string, os.FileInfo, error) {
 		if !strings.Contains(requestPath, prefix) {
 			continue
 		}
-		if len(requestPath) > len(prefix) && requestPath[len(prefix)] != '/' {
+		if prefix != "/" &&  len(requestPath) > len(prefix) && requestPath[len(prefix)] != '/' {
 			continue
 		}
 		filePath := path.Join(staticDir, requestPath[len(prefix):])