private static string CreatFileUrlMd5(string fileName) { if (null == CurVersionFileUrlMd5) { CurVersionFileUrlMd5 = new Dictionary <string, string>(); } string fileUrl = ABHelper.BuildMD5ByString(fileName); if (!CurVersionFileUrlMd5.ContainsKey(fileUrl)) { CurVersionFileUrlMd5.Add(fileUrl, fileName); } return(fileUrl); }