如果没有文件的头信息，那么需要直接通过字符串进行判断，代码通过IsUTF8String这个函数进行判断，最终得出结果。
所有的代码
procedure TForm1.Button1Click(Sender: TObject);
var
mstream: TMemoryStream;
ustream: TStringStream;
astream: TStringStream;
stream: TStringStream;
idHttpObj: TIdHTTP;
ssss: TStringList;
url: sTring;
ss: string;
rs: RawByteString;
aByte: Byte;
isFoundCode: Boolean;
begin
url := 'http://www.dfwlt.com'; // UTF8
mstream := TMemoryStream.Create;
try
idHttpObj := TIdHTTP.Create(nil);
try
Memo1.Lines.Clear;
Memo1.Lines.add(url);
Memo1.Lines.add('正在读取请稍后...');
Memo1.Lines.add('');
idHttpObj.Get(url, mstream);
mstream.Position := 0;
Memo1.Lines.Clear;
mstream.Read(aByte, 1);
isFoundCode := False;
if aByte = $FF then
begin
mstream.Read(aByte, 1);
if aByte = $EF then
begin
isFoundCode := True;
end;
end
else if aByte = $EF then
begin
mstream.Read(aByte, 1);
if aByte = $BB then
begin
mstream.Read(aByte, 1);
if aByte = $BF then
begin
isFoundCode := True;
end;
end
else if aByte = $FF then
begin
isFoundCode := True;
end;
end;
mstream.Position := 0;
if isFoundCode then
begin
//自动识别 BOM
Memo1.Lines.LoadFromStream(mstream);
end
else
begin
//没有 BOM 猜吧。
ustream := TStringStream.Create('', TEncoding.Unicode);
try
ustream.CopyFrom(mstream, 0);
astream := TStringStream.Create('', TEncoding.ANSI);
try
mstream.Position := 0;
astream.CopyFrom(mstream, 0);
if ustream.DataString <> astream.DataString then
begin
SetLength(rs, Length(astream.Bytes) + 1);
FillChar(rs[Low(string)], Length(rs), 0);
Move((@astream.Bytes[0])^, rs[Low(string)], Length(astream.Bytes));
if IsUTF8String(rs) then
begin
stream := TStringStream.Create('', TEncoding.UTF8);
try
mstream.Position := 0;
stream.CopyFrom(mstream, 0);
ss := stream.DataString;
finally
FreeAndNil(stream);
end;
end
else
begin
ss := astream.DataString;
end;
end
else
begin
ss := ustream.DataString;
end;
Memo1.Lines.Text := ss;
finally
FreeAndNil(astream);
end;
finally
FreeAndNil(ustream);
end;
end;
finally
FreeAndNil(idHttpObj);
end;
finally
FreeAndNil(mstream);
end;
end;
