德尔福:传输图像

Question

Delphi 2010

我通过自定义TCP套接字控件传输图像使用UTF-8

客户端

var
TSS: TStringStream;
STR :String;
JPG:TJPEGImage;
BMP:TBitmap;
begin
Try
BMP.LoadFromFile('C:\1.bmp');

JPG.Assign(BMP);
JPG.CompressionQuality:=80;
JPG.Compress;

TSS:=TStringStream.Create;
JPG.SaveToStream(TSS);

STR:=TSS.DataString;

MyTCPSocket.SendString(STR);


finally
BMP.free;
JPG.free;
TSS.free;
end;
end;

服务器端

Var
TSS: TStringStream;

TSS:=TStringStream.Create;
TSS.WriteString(STR);
TSS.SaveToFile('C:\2.jpg');

这段代码在同一台PC上运行很棒.

当我将图像发送到使用不同编码的其他PC接收图像但我在数据中看到许多错误字符"?????"时的问题

我认为当TStringStream将字节写入文件时,它无法将unicode字符转换为字节,因此它看起来像"？"

任何想法都非常感谢

Answer 1

您正在尝试发送二进制数据,就好像它是UTF-8编码的文本一样. 它不是,所以不要试图这样做!以原始二进制形式发送二进制数据,例如:

var
  MS: TMemoryStream;
  JPG: TJPEGImage;
  BMP: TBitmap;
begin
  MS := TMemoryStream.Create;
  try
    JPG := TJPEGImage.Create;
    try
      BMP := TBitmap.Create;
      try
        BMP.LoadFromFile('C:\1.bmp');
        JPG.Assign(BMP);
      finally
        BMP.Free;
      end;
      JPG.CompressionQuality := 80;
      JPG.Compress;
      JPG.SaveToStream(MS);
    finally
      JPG.Free;
    end;
    MS.Position := 0;
    MyTCPSocket.SendStream(MS);
  finally
    MS.free;
  end;
end;

var
  MS: TMemoryStream;
begin
  MS := TMemoryStream.Create;
  try
    MyTCPSocket.ReadStream(MS);
    MS.Position := 0;
    MS.SaveToFile('C:\2.jpg');
  finally
    MS.Free;
  end;
end;

如果必须将二进制数据作为文本发送,则需要使用真正的二进制到文本编码算法对数据进行编码,例如base64或yEnc,而不是 UTF-8(仅用于编码Unicode文本,而不是二进制数据) ,例如:

// TIdEncoderMIME and TIdDecoderMIME are part of Indy,
// which ships with Delphi, but you can use whatever
// you want...

uses
  ..., IdCoderMIME;

var
  S: String;
  MS: TMemoryStream;
  JPG: TJPEGImage;
  BMP: TBitmap;
begin
  MS := TMemoryStream.Create;
  try
    JPG := TJPEGImage.Create;
    try
      BMP := TBitmap.Create;
      try
        BMP.LoadFromFile('C:\1.bmp');
        JPG.Assign(BMP);
      finally
        BMP.Free;
      end;
      JPG.CompressionQuality := 80;
      JPG.Compress;
      JPG.SaveToStream(MS);
    finally
      JPG.Free;
    end;
    MS.Position := 0;
    S := TIdEncoderMIME.EncodeStream(MS);
  finally
    MS.free;
  end;
  MyTCPSocket.SendString(S);
end;

uses
  ..., IdCoderMIME;

var
  S: string;
  MS: TMemoryStream;
begin
  S := MyTCPSocket.ReadString;
  MS := TMemoryStream.Create;
  try
    TIdDecoderMIME.DecodeStream(S, MS);
    MS.Position := 0;
    MS.SaveToFile('C:\2.jpg');
  finally
    MS.Free;
  end;
end;