delphi 判断文本文件是否为UTF-8编码

program ConsoleTest;

{.$APPTYPE CONSOLE}

uses

  Windows,system.Classes,system.SysUtils;

const

  BOM_LENGTH = 3;

  FileName='2.txt';

var

  st: TMemoryStream;

  Buffer: array[0..BOM_LENGTH-1] of Byte;

begin

  if (FileName <> '') and FileExists(FileName) then

  begin

{$MESSAGE hint 'UTF-8 fix for TMemIniFile.LoadValues is active'}

    st := TMemoryStream.Create;

    try

      st.LoadFromFile(FileName);

      st.Position := 0;

      if BOM_LENGTH = st.Read(Buffer, BOM_LENGTH) then begin

        // the file contains at least BOM_LENGTH bytes

        if (Buffer[0] = $EF) and (Buffer[1] = $BB) and (Buffer[2] = $BF) then begin

          Writeln('UTF-8');

        end else begin

          // no BOM

          st.Position := 0;

          Writeln('no UTF-8');

        end;

      end;

     Readln;

    finally

      st.Free;

    end;

  end

  else

end.