header中没有Content-Disposition，则从url中获取文件名 (#251)

需要对合并后的代码进行越界判断处理

internal/pkg/my_util/util.go

@@ -117,7 +117,8 @@ func DownFile(l *logrus.Logger, urlStr string, _proxySettings ...*settings.Proxy
 func GetFileName(l *logrus.Logger, resp *http.Response) string {
 	contentDisposition := resp.Header.Get("Content-Disposition")
 	if len(contentDisposition) == 0 {
-		return ""
+		m := regexp.MustCompile(`^(.*/)?(?:$|(.+?)(?:(\.[^.]*$)|$))`).FindStringSubmatch(resp.Request.URL.String())
+		return m[2]+m[3]
 	}
 	re := regexp.MustCompile(`filename=["]*([^"]+)["]*`)
 	matched := re.FindStringSubmatch(contentDisposition)