var  bs: TBytes;  b: Byte;  str: string;begin  {只有 Unicode、BigEndianUnicode、UTF8 编码有识别符}  bs := TEncoding.Unicode.GetPreamble;  str := '';  for b in bs do str := Format('%s %x', [str, b]);  ShowMessage(str); {FF FE}  bs := TEncoding.BigEndianUnicode.GetPreamble;  str := '';  for b in bs do str := Format('%s %x', [str, b]);  ShowMessage(str); {FE FF}  bs := TEncoding.UTF8.GetPreamble;  str := '';  for b in bs do str := Format('%s %x', [str, b]);  ShowMessage(str); {EF BB BF}  {ASCII、UTF7 和 Default(默认编码) 没有识别符}  bs := TEncoding.ASCII.GetPreamble;  str := '';  for b in bs do str := Format('%s %x', [str, b]);  ShowMessage(str); {无}  bs := TEncoding.UTF7.GetPreamble;  str := '';  for b in bs do str := Format('%s %x', [str, b]);  ShowMessage(str); {无}  bs := TEncoding.Default.GetPreamble;  str := '';  for b in bs do str := Format('%s %x', [str, b]);  ShowMessage(str); {无} end;