/// <summary>
/// 根据前两个字节获取文件后缀名，获取不到时使用文件名截取方法获取
/// </summary>
/// <param name="filename"></param>
/// <param name="filecontent"></param>
/// <returns></returns>
public static string GetFileExt(string filename, byte[] filecontent)
{
var result = string.Empty;
if (filecontent != null && filecontent.Length > 1)
{
var fileCode = filecontent[0].ToString() + filecontent[1].ToString();
switch ((FileExtension)IntegerCore.Parse(fileCode))
{
case FileExtension.JPG:
result = "jpg";
break;
case FileExtension.JS:
result = "js";
break;
case FileExtension.GIF:
result = "gif";
break;
case FileExtension.BMP:
result = "bmp";
break;
case FileExtension.PNG:
result = "png";
break;
case FileExtension.RAR:
result = "rar";
break;
//case FileExtension.ZIP:
// result = "zip";
// break;
case FileExtension.MP3:
result = "mp3";
break;
default:
if (filecontent[0] == 0 && filecontent[1] == 0 && filecontent[2] == 0)
{
result = "mp4";
}
break;
}
}
else if (!string.IsNullOrEmpty(filename) && filename.IndexOf('.') > -1)
{
result = filename.Substring(filename.LastIndexOf('.') + 1);
}
return(result);
}
/// <summary>
/// 判断文件是否为安全文件
/// </summary>
/// <param name="stream"></param>
/// <param name="exts"></param>
/// <returns></returns>
public static bool IsSafeFile(byte[] content, params FileExtension[] exts)
{
if (content == null || content.Length < 2 || exts == null || exts.Length < 1)
{
return(false);
}
var typeStr = content[0].ToString() + content[1].ToString();
var fileType = (FileExtension)IntegerCore.Parse(typeStr);
return(exts.Contains(fileType));
}