二进制文件转成文本保存，并可以读回

以 JPEG 图片为例，以下代码演示了如何将一个 JPEG 图片保存为纯文本形式，并将其以图片形式读回并显示。
保存 TXT：

function TForm1.JpegToText(AFileName:string; SaveFile: Boolean; TxtFileName: string): string;

var

FileStream        : TFileStream;

StringStream      : TStringStream;

FSize             : integer;

FileData          : string;

i                 : integer;

DataStr           : string;

begin

try

    FileStream := TFileStream.Create(OpenDialog1.FileName, fmOpenRead);

    StringStream := TStringStream.Create(EmptyStr);

    FSize := FileStream.Size;

    StringStream.CopyFrom(FileStream, FSize);

    FileData := StringStream.DataString;

    DataStr := EmptyStr;

    for i := 1 to Length(FileData) do

    begin

      DataStr := DataStr + InttoHex(Ord(FileData[i]), 2);

    end;

    Result := DataStr;

    if SaveFile then

    begin

      with TStringList.Create do

      begin

        Text := DataStr;

        SaveToFile(TxtFileName);

        Free;

      end; 

    end; 

finally

    freeandnil(FileStream);

    freeandnil(StringStream);

end;

end;

从 TXT 读回 JPEG：

function TForm1.TextToJpeg(AFileName: string; SaveFile: Boolean; JpegFileName: string): TJPEGImage;

var

buf               : array of Byte;

DataLength        : Integer;

i                 : Integer;

DataStr           : string;

ByteFile          : file of byte;

jpg               : TJPEGImage;

tmpFileName: string;

begin

with TStringList.Create do

begin

    LoadFromFile(AFileName);

    DataStr := Text;

    Free;

end;

DataLength := Length(DataStr) div 2-1;

SetLength(buf, DataLength);

for i := 1 to DataLength do

begin

    buf[i - 1] := StrToInt('$' + copy(DataStr, (i - 1) * 2 + 1, 2));

end;

tmpFileName := ExtractFilePath(ParamStr(0))+'tmp.jpg';

AssignFile(ByteFile, tmpFileName);

Rewrite(ByteFile);

for i := 0 to DataLength - 1 do

begin

    write(ByteFile, buf[i]);

end;

CloseFile(ByteFile);

Result := TJPEGImage.Create;

Result.LoadFromFile(tmpFileName);

if SaveFile then

    Result.SaveToFile(JpegFileName);

DeleteFile(tmpFileName);

end;